#!/usr/bin/env python
# -*- coding: utf-8 -*-
"""This package provides a Python interface to the Common Data Format (CDF)
library used for many NASA missions, available at http://cdf.gsfc.nasa.gov/.
The interface is intended to be 'pythonic' rather than reproducing the
C interface. To open or close a CDF and access its variables, see the `CDF`
class. Accessing data within the variables is via the `Var`
class. The :data:`lib` object provides access to some routines
that affect the functionality of the library in general. The
`~spacepy.pycdf.const` module contains constants useful for accessing
the underlying library.
The CDF C library must be properly installed in order to use this
module. Installing SpacePy from a binary installation provides this
requirement.
The CDF distribution provides scripts meant to be called in a user's
login scripts, ``definitions.B`` for bash and ``definitions.C`` for
C-shell derivatives. (See the installation instructions which come
with the CDF library.) These will set environment variables
specifying the location of the library; pycdf will respect these
variables if they are set. Otherwise it will search the standard
system library path and the default installation locations for the CDF
library, falling back to the version shipped with the SpacePy binary
if the library is not found.
If pycdf has trouble finding the library, try setting ``CDF_LIB`` before importing
the module, e.g. if the library is in ``CDF/lib`` in the user's home directory:
>>> import os
>>> os.environ["CDF_LIB"] = "~/CDF/lib"
>>> from spacepy import pycdf
If this works, make the environment setting permanent. Note that on OSX,
using plists to set the environment may not carry over to Python terminal
sessions; use ``.cshrc`` or ``.bashrc`` instead.
Authors: Jon Niehof
Institution: University of New Hampshire
Contact: Jonathan.Niehof@unh.edu
Copyright 2010-2015 Los Alamos National Security, LLC.
"""
__contact__ = 'Jon Niehof, Jonathan.Niehof@unh.edu'
from collections.abc import MutableMapping, MutableSequence
import ctypes
import ctypes.util
import datetime
import itertools
import operator
import os
import os.path
import platform
import shutil
import sys
import tempfile
import warnings
import weakref
import numpy
import numpy.ma
import spacepy.datamodel
import spacepy.time
try:
import matplotlib.dates
HAVE_MATPLOTLIB = True
except ImportError:
HAVE_MATPLOTLIB = False
#Import const AFTER library loaded, so failed load doesn't leave half-imported
#from . import const
str_classes = (str, bytes)
def _cast_ll(x):
"""Reinterpret-cast a float to a long long
Used for typepunning ARM32 arguments.
"""
return ctypes.cast(ctypes.pointer(ctypes.c_double(x)),
ctypes.POINTER(ctypes.c_longlong)).contents
[docs]class Library(object):
"""
Abstraction of the base CDF C library and its state.
Not normally intended for end-user use. An instance of this class
is created at package load time as the :data:`~spacepy.pycdf.lib` variable, providing
access to the underlying C library if necessary. The CDF library itself
is described in section 2.1 of the CDF user's guide, as well as the CDF
C reference manual.
Calling the C library directly requires knowledge of
`ctypes`.
Instantiating this object loads the C library, see :doc:`/pycdf` docs
for details.
.. autosummary::
~Library.call
~Library.check_status
~Library.datetime_to_epoch
~Library.datetime_to_epoch16
~Library.datetime_to_tt2000
~Library.epoch_to_datetime
~Library.epoch_to_epoch16
~Library.epoch_to_num
~Library.epoch_to_tt2000
~Library.epoch16_to_datetime
~Library.epoch16_to_epoch
~Library.epoch16_to_tt2000
~Library.get_minmax
~Library.set_backward
supports_int8
~Library.tt2000_to_datetime
~Library.tt2000_to_epoch
~Library.tt2000_to_epoch16
v_datetime_to_epoch
v_datetime_to_epoch16
v_datetime_to_tt2000
v_epoch_to_datetime
v_epoch_to_tt2000
v_epoch16_to_datetime
v_epoch16_to_tt2000
v_tt2000_to_datetime
v_tt2000_to_epoch
v_tt2000_to_epoch16
libpath
version
.. automethod:: call
.. automethod:: check_status
.. automethod:: datetime_to_epoch
.. automethod:: datetime_to_epoch16
.. automethod:: datetime_to_tt2000
.. automethod:: epoch_to_datetime
.. automethod:: epoch_to_epoch16
.. automethod:: epoch_to_num
.. automethod:: epoch_to_tt2000
.. automethod:: epoch16_to_datetime
.. automethod:: epoch16_to_epoch
.. automethod:: epoch16_to_tt2000
.. automethod:: get_minmax
.. automethod:: set_backward
.. attribute:: supports_int8
True if this library supports INT8 and TIME_TT2000 types; else False.
.. automethod:: tt2000_to_datetime
.. automethod:: tt2000_to_epoch
.. automethod:: tt2000_to_epoch16
.. automethod:: v_datetime_to_epoch
.. automethod:: v_datetime_to_epoch16
.. automethod:: v_datetime_to_tt2000
.. automethod:: v_epoch_to_datetime
.. automethod:: v_epoch_to_tt2000
.. automethod:: v_epoch16_to_datetime
.. automethod:: v_epoch16_to_tt2000
.. automethod:: v_tt2000_to_datetime
.. automethod:: v_tt2000_to_epoch
.. automethod:: v_tt2000_to_epoch16
.. attribute:: libpath
The path where pycdf found the CDF C library, potentially useful in
debugging. If this contains just the name of a file (with no path
information), then the system linker found the library for pycdf.
On Linux, ``ldconfig -p`` may be useful for displaying the system's
library resolution.
.. attribute:: version
Version of the CDF library, (version, release, increment, subincrement)
"""
supports_int8 = True
"""True if this library supports INT8 and TIME_TT2000 types; else False."""
libpath = ''
"""The path where pycdf found the CDF C library, potentially useful in
debugging."""
version = (0, 0, 0, '')
"""Version of the CDF library"""
_arm32 = platform.uname()[4].startswith('arm') and sys.maxsize <= 2 ** 32
"""Excuting on 32-bit ARM, which requires typepunned arguments"""
_signatures = {
'breakdownTT2000': [None, ctypes.c_longlong]
+ [ctypes.POINTER(ctypes.c_double)] * 3,
'CDF_TT2000_from_UTC_EPOCH': [ctypes.c_longlong, ctypes.c_double],
'CDF_TT2000_from_UTC_EPOCH16': [ctypes.c_longlong,
ctypes.POINTER(ctypes.c_double * 2)],
'CDF_TT2000_to_UTC_EPOCH': [ctypes.c_double, ctypes.c_longlong],
'CDF_TT2000_to_UTC_EPOCH16': [ctypes.c_double, ctypes.c_longlong,
ctypes.POINTER(ctypes.c_double * 2)],
'CDFgetFileBackward': [ctypes.c_int],
'CDFlib': [ctypes.c_long, ctypes.c_long],
'CDFsetFileBackward': [None, ctypes.c_long],
'computeEPOCH': [ctypes.c_double] + [ctypes.c_long] * 7,
'computeEPOCH16': [ctypes.c_double] + [ctypes.c_long] * 10\
+ [ctypes.POINTER(ctypes.c_double * 2)],
'computeTT2000': [ctypes.c_longlong]
+ [ctypes.c_longlong if _arm32 else ctypes.c_double] * 3,
'EPOCH16breakdown': [None, ctypes.c_double * 2]\
+ [ctypes.POINTER(ctypes.c_long)] * 10,
'EPOCHbreakdown': [ctypes.c_long, ctypes.c_double]\
+ [ctypes.POINTER(ctypes.c_long)] * 7,
}
"""Call signatures for functions in C library. Keyed by function name;
values are return type (first element) and then argument types."""
def __init__(self, libpath=None, library=None):
"""Load the CDF C library.
Searches for the library in the order:
1. Appropriately-named file in CDF_LIB
2. Appropriately-named file in CDF_BASE
3. Standard library search path
@raise CDFError: BAD_DATA_TYPE if can't map types properly
"""
if not 'CDF_TMP' in os.environ:
os.environ['CDF_TMP'] = tempfile.gettempdir()
if not library:
if not libpath:
self.libpath, self._library = self._find_lib()
if self._library is None:
raise Exception((
'Cannot load CDF C library; checked {0}. '
'Try \'os.environ["CDF_LIB"] = library_directory\' '
'before import.').format(', '.join(self.libpath)))
else:
self._library = ctypes.CDLL(libpath)
self.libpath = libpath
else:
self._library = library
self.libpath = libpath
#Map old name to the 3.7.1+ name
if not hasattr(self._library, 'computeTT2000') \
and hasattr(self._library, 'CDF_TT2000_from_UTC_parts'):
self._library.computeTT2000 \
= self._library.CDF_TT2000_from_UTC_parts
if not hasattr(self._library, 'breakdownTT2000') \
and hasattr(self._library, 'CDF_TT2000_to_UTC_parts'):
self._library.breakdownTT2000 \
= self._library.CDF_TT2000_to_UTC_parts
for funcname in self._signatures:
func = getattr(self._library, funcname, None)
if func is None:
continue
args = self._signatures[funcname]
func.restype = args[0]
func.argtypes = None if len(args) <= 1 else args[1:]
#Get CDF version information
ver = ctypes.c_long(0)
rel = ctypes.c_long(0)
inc = ctypes.c_long(0)
sub = ctypes.c_char(b' ')
self.call(const.GET_, const.LIB_VERSION_, ctypes.byref(ver),
const.GET_, const.LIB_RELEASE_, ctypes.byref(rel),
const.GET_, const.LIB_INCREMENT_, ctypes.byref(inc),
const.GET_, const.LIB_subINCREMENT_, ctypes.byref(sub))
ver = ver.value
rel = rel.value
inc = inc.value
sub = sub.value
self.version = (ver, rel, inc, sub)
if self.version[:3] < (3, 5):
raise RuntimeError('pycdf requires CDF library 3.5')
self.supports_int8 = True # 3.4.1 for INT8, we require 3.5
self.cdftypenames = {const.CDF_BYTE.value: 'CDF_BYTE',
const.CDF_CHAR.value: 'CDF_CHAR',
const.CDF_INT1.value: 'CDF_INT1',
const.CDF_UCHAR.value: 'CDF_UCHAR',
const.CDF_UINT1.value: 'CDF_UINT1',
const.CDF_INT2.value: 'CDF_INT2',
const.CDF_UINT2.value: 'CDF_UINT2',
const.CDF_INT4.value: 'CDF_INT4',
const.CDF_UINT4.value: 'CDF_UINT4',
const.CDF_INT8.value: 'CDF_INT8',
const.CDF_FLOAT.value: 'CDF_FLOAT',
const.CDF_REAL4.value: 'CDF_REAL4',
const.CDF_DOUBLE.value: 'CDF_DOUBLE',
const.CDF_REAL8.value: 'CDF_REAL8',
const.CDF_EPOCH.value: 'CDF_EPOCH',
const.CDF_EPOCH16.value: 'CDF_EPOCH16',
const.CDF_TIME_TT2000.value: 'CDF_TIME_TT2000',
}
self.numpytypedict = {const.CDF_BYTE.value: numpy.int8,
const.CDF_CHAR.value: numpy.int8,
const.CDF_INT1.value: numpy.int8,
const.CDF_UCHAR.value: numpy.uint8,
const.CDF_UINT1.value: numpy.uint8,
const.CDF_INT2.value: numpy.int16,
const.CDF_UINT2.value: numpy.uint16,
const.CDF_INT4.value: numpy.int32,
const.CDF_UINT4.value: numpy.uint32,
const.CDF_INT8.value: numpy.int64,
const.CDF_FLOAT.value: numpy.float32,
const.CDF_REAL4.value: numpy.float32,
const.CDF_DOUBLE.value: numpy.float64,
const.CDF_REAL8.value: numpy.float64,
const.CDF_EPOCH.value: numpy.float64,
const.CDF_EPOCH16.value:
numpy.dtype((numpy.float64, 2)),
const.CDF_TIME_TT2000.value: numpy.int64,
}
self.timetypes = [const.CDF_EPOCH.value,
const.CDF_EPOCH16.value,
const.CDF_TIME_TT2000.value]
if self._arm32:
# Type-pun double arguments to variadic functions.
# Calling convention for non-variadic functions with floats
# is unique, but convention for ints is same as variadic.
if ctypes.sizeof(ctypes.c_longlong) != \
ctypes.sizeof(ctypes.c_double):
warnings.warn('ARM with unknown type sizes; '
'TT2000 functions will not work.')
else:
if self._library.computeTT2000(
_cast_ll(2010), _cast_ll(1), _cast_ll(1),
_cast_ll(0), _cast_ll(0), _cast_ll(0),
_cast_ll(0), _cast_ll(0), _cast_ll(0)
) != 315576066184000000:
warnings.warn('ARM with unknown calling convention; '
'TT2000 functions will not work.')
self.datetime_to_tt2000 = self._datetime_to_tt2000_typepunned
if self.epoch_to_datetime(63113903999999.984).year != 1999:
self.epoch_to_datetime = self._epoch_to_datetime_bad_rounding
v_epoch16_to_datetime = numpy.frompyfunc(
self.epoch16_to_datetime, 2, 1)
self.v_epoch16_to_datetime = \
lambda x: v_epoch16_to_datetime(x[..., 0], x[..., 1])
self.v_epoch_to_datetime = numpy.frompyfunc(
self.epoch_to_datetime, 1, 1)
self.v_tt2000_to_datetime = numpy.frompyfunc(
self.tt2000_to_datetime, 1, 1)
self.v_datetime_to_epoch = numpy.vectorize(
self.datetime_to_epoch, otypes=[numpy.float64])
v_datetime_to_epoch16 = numpy.frompyfunc(
self.datetime_to_epoch16, 1, 2)
#frompyfunc returns a TUPLE of the returned values,
#implicitly the 0th dimension. We want everything from one
#call paired, so this rolls the 0th dimension to the last
#(via the second-to-last)
def _v_datetime_to_epoch16(x):
retval = numpy.require(v_datetime_to_epoch16(x),
dtype=numpy.float64)
if len(retval.shape) > 1:
return numpy.rollaxis(
numpy.rollaxis(retval, 0, -1),
-1, -2)
else:
return retval
self.v_datetime_to_epoch16 = _v_datetime_to_epoch16
self.v_datetime_to_tt2000 = numpy.vectorize(
self.datetime_to_tt2000, otypes=[numpy.int64])
self.v_epoch_to_tt2000 = numpy.vectorize(
self.epoch_to_tt2000, otypes=[numpy.int64])
self.v_tt2000_to_epoch = numpy.vectorize(
self.tt2000_to_epoch, otypes=[numpy.float64])
v_epoch16_to_tt2000 = numpy.frompyfunc(
self.epoch16_to_tt2000, 2, 1)
self.v_epoch16_to_tt2000 = \
lambda x: v_epoch16_to_tt2000(x[..., 0], x[..., 1])
v_tt2000_to_epoch16 = numpy.frompyfunc(
self.tt2000_to_epoch16, 1, 2)
#frompyfunc returns a TUPLE of the returned values,
#implicitly the 0th dimension. We want everything from one
#call paired, so this rolls the 0th dimension to the last
#(via the second-to-last)
def _v_tt2000_to_epoch16(x):
retval = numpy.require(v_tt2000_to_epoch16(x),
dtype=numpy.float64)
if len(retval.shape) > 1:
return numpy.rollaxis(
numpy.rollaxis(retval, 0, -1),
-1, -2)
else:
return retval
self.v_tt2000_to_epoch16 = _v_tt2000_to_epoch16
@staticmethod
def _find_lib():
"""
Search for the CDF library
Searches in likely locations for CDF libraries and attempts to load
them. Stops at first successful load and, if fails, reports all
the files that were tried as libraries.
Returns
=======
out : tuple
This is either (path to library, loaded library)
or, in the event of failure, (None, list of libraries tried)
"""
failed = []
for libpath in Library._lib_paths():
try:
lib = ctypes.CDLL(libpath)
except:
failed.append(libpath)
else:
return libpath, lib
return (failed, None)
@staticmethod
def _lib_paths():
"""Find candidate paths for the CDF library
Does not check that the library is actually in any particular directory,
just returns a list of possible locations, in priority order.
Returns
=======
out : generator of str
paths that look like the CDF library
"""
#What the library might be named
names = { 'win32': ['dllcdf.dll'],
'darwin': ['libcdf.dylib', 'cdf.dylib', 'libcdf.so'],
'linux2': ['libcdf.so'],
'linux': ['libcdf.so'],
}
names = names.get(sys.platform, ['libcdf.so'])
#All existing CDF-library-like paths within a directory
search_dir = lambda x: \
[os.path.join(x, fname) for fname in names
if os.path.exists(os.path.join(x, fname))]
#Search the environment-specified places first
if 'CDF_LIB' in os.environ:
for p in search_dir(os.environ['CDF_LIB']):
yield p
if sys.platform == 'win32' and 'CDF_BIN' in os.environ:
for p in search_dir(os.environ['CDF_BIN']):
yield p
if 'CDF_BASE' in os.environ:
for p in search_dir(os.path.join(os.environ['CDF_BASE'], 'lib')):
yield p
if sys.platform == 'win32':
for p in search_dir(
os.path.join(os.environ['CDF_BASE'], 'bin')):
yield p
ctypespath = ctypes.util.find_library(
'dllcdf.dll' if sys.platform == 'win32' else 'cdf')
if ctypespath:
yield ctypespath
#LD_LIBRARY_PATH specifies runtime library search paths
if 'LD_LIBRARY_PATH' in os.environ:
for d in os.environ['LD_LIBRARY_PATH'].split(os.pathsep):
for p in search_dir(d):
yield p
#Finally, defaults places CDF gets installed uner
#CDF_BASE is usually a subdir of these (with "cdf" in the name)
#Searched in order given here!
cdfdists = {
'win32': [
os.getenv('SystemDrive', 'c:') + root + extra
for root in ['', '\\Program Files', '\\Program Files (x86)']
for extra in ['\\CDF Distribution\\', '\\CDF_Distribution\\']],
'darwin': ['/Applications/', os.path.expanduser('~/Applications/'),
'/Applications/cdf/',
os.path.expanduser('~/Applications/cdf/'),
'/usr/local/', os.path.expanduser('~')],
'linux2': ['/usr/local/', os.path.expanduser('~')],
'linux': ['/usr/local/', os.path.expanduser('~')],
}
for cdfdist in cdfdists.get(sys.platform, []):
if os.path.isdir(cdfdist):
cand = []
for d in os.listdir(cdfdist):
if d[0:3].lower() == 'cdf':
#checking src in case BUILT but not INSTALLED
for subdir in ['lib', os.path.join('src', 'lib'),
'bin']:
libdir = os.path.join(cdfdist, d, subdir)
if os.path.isdir(libdir):
cand.append(libdir)
#Sort reverse, so new versions are first FOR THIS cdfdist
for d in sorted(cand)[::-1]:
for p in search_dir(d):
yield p
# Check for a version shipped with SpacePy binary wheels
if isinstance(__file__, str):
spdir = os.path.dirname(os.path.dirname(os.path.abspath(__file__)))
if os.path.isdir(spdir):
for p in search_dir(spdir):
yield p
[docs] def check_status(self, status, ignore=()):
"""
Raise exception or warning based on return status of CDF call
Parameters
==========
status : int
status returned by the C library
Other Parameters
================
ignore : sequence of ctypes.c_long
CDF statuses to ignore. If any of these is returned by CDF library,
any related warnings or exceptions will *not* be raised.
(Default none).
Raises
======
CDFError : if status < CDF_WARN, indicating an error
Warns
=====
CDFWarning : if CDF_WARN <= status < CDF_OK, indicating a warning.
Returns
=======
out : int
status (unchanged)
"""
if status == const.CDF_OK or status in ignore:
return status
if status < const.CDF_WARN:
raise CDFError(status)
else:
warning = CDFWarning(status)
warning.warn()
return status
[docs] def call(self, *args, **kwargs):
"""
Call the CDF internal interface
Passes all parameters directly through to the CDFlib routine of the
CDF library's C internal interface. Checks the return value with
:meth:`check_status`.
Terminal NULL is automatically added to args.
Parameters
==========
args : various, see `ctypes`
Passed directly to the CDF library interface. Useful
constants are defined in the `~pycdf.const` module.
Other Parameters
================
ignore : sequence of CDF statuses
sequence of CDF statuses to ignore. If any of these
is returned by CDF library, any related warnings or
exceptions will *not* be raised.
Returns
=======
out : int
CDF status from the library
Raises
======
CDFError : if CDF library reports an error
Warns
=====
CDFWarning : if CDF library reports a warning
"""
if 'ignore' in kwargs:
return self.check_status(self._library.CDFlib(
*(args + (const.NULL_, ))
), kwargs['ignore'])
else:
return self.check_status(self._library.CDFlib(
*(args + (const.NULL_, ))
))
[docs] def set_backward(self, backward=True):
"""
Set backward compatibility mode for new CDFs
Unless backward compatible mode is set, CDF files created by
the version 3 library can not be read by V2. pycdf does not
set backward compatible mode by default.
.. versionchanged:: 0.3.0
Before 0.3.0, pycdf set backward compatible mode on import.
Parameters
==========
backward : bool, optional
Set backward compatible mode if True; clear it if False. If not
specified, will not change current setting.
.. versionchanged:: 0.5.0
Added ability to not change setting (previously defaulted
to setting backward compatible).
Returns
=======
bool
Previous value of backward-compatible mode.
.. versionadded:: 0.5.0
Raises
======
ValueError : if backward=False and underlying CDF library is V2
"""
former = bool(self._library.CDFgetFileBackward())
if backward is not None:
self._library.CDFsetFileBackward(
const.BACKWARDFILEon if backward else const.BACKWARDFILEoff)
return former
[docs] def epoch_to_datetime(self, epoch):
"""
Converts a CDF epoch value to a datetime
Parameters
==========
epoch : float
epoch value from CDF
Returns
=======
out : `datetime.datetime`
date and time corresponding to epoch. Invalid values are set to
usual epoch invalid value, i.e. last moment of year 9999.
See Also
========
v_epoch_to_datetime
"""
yyyy = ctypes.c_long(0)
mm = ctypes.c_long(0)
dd = ctypes.c_long(0)
hh = ctypes.c_long(0)
mn = ctypes.c_long(0)
sec = ctypes.c_long(0)
msec = ctypes.c_long(0)
self._library.EPOCHbreakdown(epoch, yyyy, mm, dd, hh, mn, sec, msec)
if yyyy.value <= 0:
return datetime.datetime(9999, 12, 13, 23, 59, 59, 999000)
else:
return datetime.datetime(yyyy.value, mm.value, dd.value,
hh.value, mn.value, sec.value,
msec.value * 1000)
def _epoch_to_datetime_bad_rounding(self, epoch):
"""
Converts a CDF epoch value to a datetime
Version for libraries before CDF 3.8.0.1, which would erroneously
convert times near end of day into the next day.
Parameters
==========
epoch : float
epoch value from CDF
Returns
=======
out : :class:`datetime.datetime`
date and time corresponding to epoch. Invalid values are set to
usual epoch invalid value, i.e. last moment of year 9999.
See Also
========
v_epoch_to_datetime
"""
yyyy = ctypes.c_long(0)
mm = ctypes.c_long(0)
dd = ctypes.c_long(0)
hh = ctypes.c_long(0)
mn = ctypes.c_long(0)
sec = ctypes.c_long(0)
msec = ctypes.c_long(0)
# Truncate to ms inherent EPOCH resolution to avoid rounding bug
self._library.EPOCHbreakdown(
int(epoch), yyyy, mm, dd, hh, mn, sec, msec)
if yyyy.value <= 0:
return datetime.datetime(9999, 12, 13, 23, 59, 59, 999000)
else:
return datetime.datetime(yyyy.value, mm.value, dd.value,
hh.value, mn.value, sec.value,
msec.value * 1000)
[docs] def datetime_to_epoch(self, dt):
"""
Converts a Python datetime to a CDF Epoch value
Parameters
==========
dt : `datetime.datetime`
date and time to convert
Returns
=======
out : float
epoch corresponding to dt
See Also
========
v_datetime_to_epoch
"""
if dt.tzinfo != None and dt.utcoffset() != None:
dt = dt - dt.utcoffset()
dt.replace(tzinfo=None)
micro = dt.microsecond % 1000
if micro >= 500 and dt.year < 9999:
dt += datetime.timedelta(0, 0, 1000)
return self._library.computeEPOCH(dt.year, dt.month, dt.day, dt.hour,
dt.minute, dt.second,
int(dt.microsecond / 1000))
[docs] def epoch16_to_datetime(self, epoch0, epoch1):
"""
Converts a CDF epoch16 value to a datetime
.. note::
The call signature has changed since SpacePy 0.1.2. Formerly
this method took a single argument with two values; now it
requires two arguments (one for each value). To convert existing
code, replace ``epoch16_to_datetime(epoch)`` with
``epoch16_to_datetime(*epoch)``.
Parameters
==========
epoch0 : float
epoch16 value from CDF, first half
epoch1 : float
epoch16 value from CDF, second half
Raises
======
EpochError : if input invalid
Returns
=======
out : `datetime.datetime`
date and time corresponding to epoch. Invalid values are set to
usual epoch invalid value, i.e. last moment of year 9999.
See Also
========
v_epoch16_to_datetime
"""
yyyy = ctypes.c_long(0)
mm = ctypes.c_long(0)
dd = ctypes.c_long(0)
hh = ctypes.c_long(0)
mn = ctypes.c_long(0)
sec = ctypes.c_long(0)
msec = ctypes.c_long(0)
usec = ctypes.c_long(0)
nsec = ctypes.c_long(0)
psec = ctypes.c_long(0)
self._library.EPOCH16breakdown(
(ctypes.c_double * 2)(epoch0, epoch1),
yyyy, mm, dd, hh, mn, sec,
msec, usec, nsec, psec)
if yyyy.value <= 0:
return datetime.datetime(9999, 12, 13, 23, 59, 59, 999999)
micro = int(float(msec.value) * 1000 + float(usec.value) +
float(nsec.value) / 1000 + float(psec.value) / 1e6 + 0.5)
if micro < 1000000:
return datetime.datetime(yyyy.value, mm.value, dd.value,
hh.value, mn.value, sec.value,
micro)
else:
add_sec = int(micro / 1000000)
try:
return datetime.datetime(yyyy.value, mm.value, dd.value,
hh.value, mn.value, sec.value,
micro - add_sec * 1000000) + \
datetime.timedelta(seconds=add_sec)
except OverflowError:
return datetime.datetime(datetime.MAXYEAR, 12, 31,
23, 59, 59,
999999)
[docs] def datetime_to_epoch16(self, dt):
"""
Converts a Python datetime to a CDF Epoch16 value
Parameters
==========
dt : `datetime.datetime`
date and time to convert
Returns
=======
out : list of float
epoch16 corresponding to dt
See Also
========
v_datetime_to_epoch16
"""
if dt.tzinfo != None and dt.utcoffset() != None:
dt = dt - dt.utcoffset()
dt.replace(tzinfo=None)
#Default to "illegal epoch"
epoch16 = (ctypes.c_double * 2)(-1., -1.)
if self._library.computeEPOCH16(dt.year, dt.month, dt.day, dt.hour,
dt.minute, dt.second,
int(dt.microsecond / 1000),
dt.microsecond % 1000, 0, 0,
epoch16):
return (-1., -1.) #Failure, so illegal epoch
return (epoch16[0], epoch16[1])
[docs] def epoch_to_epoch16(self, epoch):
"""
Converts a CDF EPOCH to a CDF EPOCH16 value
Parameters
==========
epoch : double
EPOCH to convert. Lists and numpy arrays are acceptable.
Returns
=======
out : (double, double)
EPOCH16 corresponding to epoch
"""
e = numpy.require(epoch, numpy.float64)
s = numpy.trunc(e / 1000.0)
#ugly numpy stuff, probably a better way....
res = numpy.hstack((s, (e - s * 1000.0) * 1e9))
if len(res) <= 2:
return res
newshape = list(res.shape[0:-2])
newshape.append(res.shape[-1] // 2)
newshape.append(2)
return numpy.rollaxis(res.reshape(newshape), -1, -2)
[docs] def epoch_to_num(self, epoch):
"""
Convert CDF EPOCH to matplotlib number.
Same output as `~matplotlib.dates.date2num` and useful for
plotting large data sets without converting the times through datetime.
Parameters
==========
epoch : double
EPOCH to convert. Lists and numpy arrays are acceptable.
Returns
=======
out : double
Floating point number representing days since matplotlib
epoch (usually 0001-01-01 as day 1, or 1970-01-01 as day 0).
See Also
========
matplotlib.dates.date2num, matplotlib.dates.num2date
Notes
=====
This number is not portable between versions of matplotlib. The
returned value is for the installed version of matplotlib. If
matplotlib is not found, the returned value is for matplotlib 3.2
and earlier.
"""
#date2num day 1 is 1/1/1 00UT
#epoch 1/1/1 00UT is 31622400000.0 (millisecond)
# So day 0 is 31536000000.0
baseepoch = 31536000000.0
if HAVE_MATPLOTLIB and hasattr(matplotlib.dates, 'get_epoch'):
# Different day 0
baseepoch = spacepy.time.Ticktock(matplotlib.dates.get_epoch())\
.CDF[0]
return (epoch - baseepoch) / (24 * 60 * 60 * 1000.0)
[docs] def epoch16_to_epoch(self, epoch16):
"""
Converts a CDF EPOCH16 to a CDF EPOCH value
Parameters
==========
epoch16 : (double, double)
EPOCH16 to convert. Lists and numpy arrays are acceptable.
LAST dimension should be 2: the two pairs of EPOCH16
Returns
=======
out : double
EPOCH corresponding to epoch16
"""
e = numpy.require(epoch16, numpy.float64)
return e[..., 0] * 1000.0 + numpy.round(e[..., 1] / 1e9)
[docs] def tt2000_to_datetime(self, tt2000):
"""
Converts a CDF TT2000 value to a datetime
.. note::
Although TT2000 values support leapseconds, Python's datetime
object does not. Any times after 23:59:59.999999 will
be truncated to 23:59:59.999999.
Parameters
==========
tt2000 : int
TT2000 value from CDF
Raises
======
EpochError : if input invalid
Returns
=======
out : `datetime.datetime`
date and time corresponding to epoch. Invalid values are set to
usual epoch invalid value, i.e. last moment of year 9999.
See Also
========
v_tt2000_to_datetime
"""
yyyy = ctypes.c_double(0)
mm = ctypes.c_double(0)
dd = ctypes.c_double(0)
hh = ctypes.c_double(0)
mn = ctypes.c_double(0)
sec = ctypes.c_double(0)
msec = ctypes.c_double(0)
usec = ctypes.c_double(0)
nsec = ctypes.c_double(0)
self._library.breakdownTT2000(
tt2000, yyyy, mm, dd,
ctypes.byref(hh), ctypes.byref(mn), ctypes.byref(sec),
ctypes.byref(msec), ctypes.byref(usec), ctypes.byref(nsec))
if yyyy.value <= 0:
return datetime.datetime(9999, 12, 13, 23, 59, 59, 999999)
sec = int(sec.value)
if sec >= 60:
return datetime.datetime(
int(yyyy.value), int(mm.value), int(dd.value),
int(hh.value), int(mn.value), 59, 999999)
micro = int(msec.value * 1000 + usec.value + nsec.value / 1000 + 0.5)
if micro < 1000000:
return datetime.datetime(
int(yyyy.value), int(mm.value), int(dd.value),
int(hh.value), int(mn.value), sec, micro)
else:
add_sec = int(micro / 1000000)
try:
return datetime.datetime(
int(yyyy.value), int(mm.value), int(dd.value),
int(hh.value), int(mn.value), sec,
micro - add_sec * 1000000) + \
datetime.timedelta(seconds=add_sec)
except OverflowError:
return datetime.datetime(datetime.MAXYEAR, 12, 31,
23, 59, 59, 999999)
[docs] def datetime_to_tt2000(self, dt):
"""
Converts a Python datetime to a CDF TT2000 value
Parameters
==========
dt : `datetime.datetime`
date and time to convert
Returns
=======
out : int
tt2000 corresponding to dt
See Also
========
v_datetime_to_tt2000
"""
if dt.tzinfo != None and dt.utcoffset() != None:
dt = dt - dt.utcoffset()
dt = dt.replace(tzinfo=None)
if dt == datetime.datetime.max:
return -2**63
return self._library.computeTT2000(
dt.year, dt.month, dt.day,
ctypes.c_double(dt.hour), ctypes.c_double(dt.minute),
ctypes.c_double(dt.second),
ctypes.c_double(int(dt.microsecond / 1000)),
ctypes.c_double(dt.microsecond % 1000), ctypes.c_double(0))
def _datetime_to_tt2000_typepunned(self, dt):
"""
Converts a Python datetime to a CDF TT2000 value
Typepunned version that passes doubles as longlongs, to get around
ARM calling convention oddness.
Parameters
==========
dt : `datetime.datetime`
date and time to convert
Returns
=======
out : int
tt2000 corresponding to dt
See Also
========
v_datetime_to_tt2000
"""
if dt.tzinfo != None and dt.utcoffset() != None:
dt = dt - dt.utcoffset()
dt = dt.replace(tzinfo=None)
if dt == datetime.datetime.max:
return -2**63
return self._library.computeTT2000(
_cast_ll(dt.year), _cast_ll(dt.month), _cast_ll(dt.day),
_cast_ll(dt.hour), _cast_ll(dt.minute), _cast_ll(dt. second),
_cast_ll(dt.microsecond // 1000), _cast_ll(dt.microsecond % 1000),
_cast_ll(0))
[docs] def epoch_to_tt2000(self, epoch):
"""
Converts a CDF EPOCH to a CDF TT2000 value
Parameters
==========
epoch : double
EPOCH to convert
Returns
=======
out : int
tt2000 corresponding to epoch
See Also
========
v_epoch_to_tt2000
"""
return self._library.CDF_TT2000_from_UTC_EPOCH(epoch)
[docs] def tt2000_to_epoch(self, tt2000):
"""
Converts a CDF TT2000 value to a CDF EPOCH
.. note::
Although TT2000 values support leapseconds, CDF EPOCH values
do not. Times during leapseconds are rounded up to beginning
of the next day.
Parameters
==========
tt2000 : int
TT2000 value from CDF
Raises
======
EpochError : if input invalid
Returns
=======
out : double
EPOCH corresponding to the TT2000 input time
See Also
========
v_tt2000_to_epoch
"""
return self._library.CDF_TT2000_to_UTC_EPOCH(tt2000)
[docs] def epoch16_to_tt2000(self, epoch0, epoch1):
"""
Converts a CDF epoch16 value to TT2000
.. note::
Because TT2000 does not support picoseconds, the picoseconds
value in epoch is ignored (i.e., truncated.)
Parameters
==========
epoch0 : float
epoch16 value from CDF, first half
epoch1 : float
epoch16 value from CDF, second half
Raises
======
EpochError : if input invalid
Returns
=======
out : long
TT2000 corresponding to epoch.
See Also
========
v_epoch16_to_tt2000
"""
return self._library.CDF_TT2000_from_UTC_EPOCH16(
(ctypes.c_double * 2)(epoch0, epoch1))
[docs] def tt2000_to_epoch16(self, tt2000):
"""
Converts a CDF TT2000 value to a CDF EPOCH16
.. note::
Although TT2000 values support leapseconds, CDF EPOCH16 values
do not. Times during leapseconds are rounded up to beginning
of the next day.
Parameters
==========
tt2000 : int
TT2000 value from CDF
Raises
======
EpochError : if input invalid
Returns
=======
out : double, double
EPOCH16 corresponding to the TT2000 input time
See Also
========
v_tt2000_to_epoch16
"""
#Default to "illegal epoch" if isn't populated
epoch16 = (ctypes.c_double * 2)(-1., -1.)
if self._library.CDF_TT2000_to_UTC_EPOCH16(tt2000, epoch16):
return (-1., -1.) #Failure; illegal epoch
return (epoch16[0], epoch16[1])
def _bad_tt2000(*args, **kwargs):
"""Convenience function for complaining that TT2000 not supported"""
raise NotImplementedError(
'TT2000 functions require CDF library 3.4.0 or later')
[docs] def get_minmax(self, cdftype):
"""Find minimum, maximum possible value based on CDF type.
This returns the processed value (e.g. datetimes for Epoch
types) because comparisons to EPOCH16s are otherwise
difficult.
Parameters
==========
cdftype : int
CDF type number from `~spacepy.pycdf.const`
Raises
======
ValueError : if can't match the type
Returns
=======
out : tuple
minimum, maximum value supported by type (of type matching the
CDF type).
"""
try:
cdftype = cdftype.value
except:
pass
if cdftype == spacepy.pycdf.const.CDF_EPOCH.value:
return (datetime.datetime(1, 1, 1),
#Can get asymptotically closer, but why bother
datetime.datetime(9999, 12, 31, 23, 59, 59))
elif cdftype == spacepy.pycdf.const.CDF_EPOCH16.value:
return (datetime.datetime(1, 1, 1),
datetime.datetime(9999, 12, 31, 23, 59, 59))
elif cdftype == spacepy.pycdf.const.CDF_TIME_TT2000.value:
inf = numpy.iinfo(numpy.int64)
#Using actual min results in invalid/fill value
return (self.tt2000_to_datetime(inf.min + 2),
self.tt2000_to_datetime(inf.max))
dtype = spacepy.pycdf.lib.numpytypedict.get(cdftype, None)
if dtype is None:
raise ValueError('Unknown data type: {}'.format(cdftype))
if numpy.issubdtype(dtype, numpy.integer):
inf = numpy.iinfo(dtype)
elif numpy.issubdtype(dtype, numpy.floating):
inf = numpy.finfo(dtype)
else:
raise ValueError('Unknown data type: {}'.format(cdftype))
return (inf.min, inf.max)
# Stubs of vectorized functions for documentation; actual versions
# are populated when class instantiated.
[docs] def v_datetime_to_epoch(self, datetime):
"""A vectorized version of `datetime_to_epoch`.
Takes a numpy array of datetimes as input and returns an array of
epochs.
"""
pass
[docs] def v_datetime_to_epoch16(self, datetime):
"""A vectorized version of `datetime_to_epoch16`.
Takes a numpy array of datetimes as input and returns an array of
epoch16.
"""
pass
[docs] def v_datetime_to_tt2000(self, datetime):
"""A vectorized version of `datetime_to_tt2000`.
Takes a numpy array of datetimes as input and returns an array of
TT2000.
"""
pass
[docs] def v_epoch_to_datetime(self, epoch):
"""A vectorized version of `epoch_to_datetime`.
Takes a numpy array of epochs as input and returns an array of
datetimes.
"""
pass
[docs] def v_epoch_to_tt2000(self, epoch):
"""A vectorized version of `epoch_to_tt2000`.
Takes a numpy array of epochs as input and returns an array of
tt2000s.
"""
pass
[docs] def v_epoch16_to_datetime(self, epoch):
"""A vectorized version of `epoch16_to_datetime`.
Takes a numpy array of epoch16 as input and returns an array of
datetimes. An epoch16 is a pair of doubles; the input array's last
dimension must be two (and the returned array will have one fewer
dimension).
"""
pass
[docs] def v_epoch16_to_tt2000(self, epoch16):
"""A vectorized version of `epoch16_to_tt2000`.
Takes a numpy array of epoch16 as input and returns an array of
tt2000s. An epoch16 is a pair of doubles; the input array's last
dimension must be two (and the returned array will have one fewer
dimension).
"""
pass
[docs] def v_tt2000_to_datetime(self, tt2000):
"""A vectorized version of `tt2000_to_datetime`.
Takes a numpy array of tt2000 as input and returns an array of
datetimes.
"""
pass
[docs] def v_tt2000_to_epoch(self, tt2000):
"""A vectorized version of `tt2000_to_epoch`.
Takes a numpy array of tt2000 as input and returns an array of
epochs.
"""
pass
[docs] def v_tt2000_to_epoch16(self, tt2000):
"""A vectorized version of `tt2000_to_epoch16`.
Takes a numpy array of tt2000 as input and returns an array of
epoch16.
"""
pass
_libpath, _library = Library._find_lib()
if _library is None:
raise Exception(('Cannot load CDF C library; checked {0}. '
'Try \'os.environ["CDF_LIB"] = library_directory\' '
'before import.').format(', '.join(_libpath)))
from . import const
lib = Library(_libpath, _library)
"""Module global library object.
Initalized at module load time so all classes have ready
access to the CDF library and a common state. E.g:
>>> from spacepy import pycdf
>>> pycdf.lib.version
(3, 3, 0, ' ')
"""
[docs]class CDFException(Exception):
"""
Base class for errors or warnings in the CDF library.
Not normally used directly, but in subclasses `CDFError`
and `CDFWarning`.
Error messages provided by this class are looked up from the underlying
C library.
"""
def __init__(self, status):
"""
Create a CDF Exception
Uses CDF C library to look up an appropriate error message.
Parameters
==========
status : ctypes.c_long
CDF status
"""
self.status = status
self.string = 'CDF error ' + repr(status) + ', unable to get details.'
message = ctypes.create_string_buffer(const.CDF_STATUSTEXT_LEN + 1)
try:
retval = lib._library.CDFlib(const.SELECT_, const.CDF_STATUS_,
ctypes.c_long(status),
const.GET_, const.STATUS_TEXT_, message,
const.NULL_)
if retval == const.CDF_OK:
if isinstance(message.value, str):
self.string = message.value
elif isinstance(message.value, bytes):
self.string = message.value.decode()
except:
pass
def __str__(self):
"""
Error string associated with the library error.
Returns
=======
out : str
Error message from the CDF library.
"""
return self.string
[docs]class CDFError(CDFException):
"""Raised for an error in the CDF library."""
pass
[docs]class CDFWarning(CDFException, UserWarning):
"""Used for a warning in the CDF library."""
def warn(self, level=4):
"""
Issues a warning based on the information stored in my exception
Intended for use in check_status or similar wrapper function.
Other Parameters
================
level : int
optional (default 3), how far up the stack the warning should
be reported. Passed directly to `warnings.warn`.
"""
warnings.warn(self, self.__class__, level)
[docs]class EpochError(Exception):
"""Used for errors in epoch routines"""
pass
def _compress(obj, comptype=None, param=None):
"""Set or check the compression of a `pycdf.CDF` or `pycdf.Var`
@param obj: object on which to set or check compression
@type obj: `pycdf.CDF` or `pycdf.Var`
@param comptype: type of compression to change to, see CDF C reference
manual section 4.10. Constants for this parameter
are in `pycdf.const`. If not specified, will not change
compression.
@type comptype: ctypes.c_long
@param param: Compression parameter, see CDF CRM 4.10 and `pycdf.const`.
If not specified, will choose reasonable default (5 for
gzip; other types have only one possible parameter.)
@type param: ctypes.c_long
@return: (comptype, param) currently in effect
@rtype: tuple
"""
if isinstance(obj, CDF):
COMPRESSION_ = const.CDF_COMPRESSION_
elif isinstance(obj, Var):
COMPRESSION_ = const.zVAR_COMPRESSION_
else:
raise ValueError('Must specify a CDF or Var type.')
validparams = {const.NO_COMPRESSION.value: [ctypes.c_long(0)],
const.RLE_COMPRESSION.value: [const.RLE_OF_ZEROs],
const.HUFF_COMPRESSION.value:
[const.OPTIMAL_ENCODING_TREES],
const.AHUFF_COMPRESSION.value:
[const.OPTIMAL_ENCODING_TREES],
const.GZIP_COMPRESSION.value: [ctypes.c_long(5),
ctypes.c_long(1),
ctypes.c_long(2),
ctypes.c_long(3),
ctypes.c_long(4),
ctypes.c_long(6),
ctypes.c_long(7),
ctypes.c_long(8),
ctypes.c_long(9),
],
}
comptypes = [const.NO_COMPRESSION, const.RLE_COMPRESSION,
const.HUFF_COMPRESSION, const.AHUFF_COMPRESSION,
const.GZIP_COMPRESSION]
comptypevalues = [i.value for i in comptypes]
if comptype != None:
if not hasattr(comptype, 'value'):
comptype = ctypes.c_long(comptype)
if param is None:
if not comptype.value in validparams:
raise CDFError(const.BAD_COMPRESSION)
param = validparams[comptype.value][0]
paramlist = (ctypes.c_long * 1)(param)
obj._call(const.PUT_, COMPRESSION_,
comptype, paramlist)
params = (ctypes.c_long *
const.CDF_MAX_PARMS)(*([0] * const.CDF_MAX_PARMS))
comptype = ctypes.c_long(0)
percent = ctypes.c_long(0)
obj._call(const.GET_, COMPRESSION_,
ctypes.byref(comptype), ctypes.byref(params),
ctypes.byref(percent))
param = params[0]
if not comptype.value in comptypevalues:
raise CDFError(const.BAD_COMPRESSION)
validparamvalues = [i.value for i in validparams[comptype.value]]
if not param in validparamvalues:
raise CDFError(const.BAD_COMPRESSION_PARM)
comptype = comptypes[comptypevalues.index(comptype.value)]
if comptype in (const.RLE_COMPRESSION, const.HUFF_COMPRESSION,
const.AHUFF_COMPRESSION):
param = validparams[comptype.value][validparamvalues.index(param)]
return (comptype, param)
[docs]class CDF(MutableMapping, spacepy.datamodel.MetaMixin):
"""
Python object representing a CDF file.
Open or create a CDF file by creating an object of this class.
Parameters
==========
pathname : string
name of the file to open or create
masterpath : string
name of the master CDF file to use in creating
a new file. If not provided, an existing file is
opened; if provided but evaluates to ``False``
(e.g., ``''``), an empty new CDF is created.
create : bool
Create a new CDF even if masterpath isn't provided
readonly : bool
Open the CDF read-only. Default True if opening an
existing CDF; False if creating a new one. A readonly
CDF with many variables may be slow to close on CDF library
versions before 3.8.1. See :meth:`readonly`.
encoding : str, optional
Text encoding to use when reading and writing strings. Default
``'utf-8'``.
Raises
======
CDFError
if CDF library reports an error
Warns
=====
CDFWarning
if CDF library reports a warning and interpreter
is set to error on warnings.
Examples
========
Open a CDF by creating a CDF object, e.g.:
>>> cdffile = pycdf.CDF('cdf_filename.cdf')
Be sure to :meth:`close` or :meth:`save` when
done.
.. note::
Existing CDF files are opened read-only by default, see
:meth:`readonly` to change.
CDF supports the `with
<http://docs.python.org/tutorial/inputoutput.html#methods-of-file-objects>`_
keyword, like other file objects, so:
>>> with pycdf.CDF('cdf_filename.cdf') as cdffile:
... #do brilliant things with the CDF
will open the CDF, execute the indented statements, and close the CDF when
finished or when an error occurs. The `python docs
<http://docs.python.org/reference/compound_stmts.html#with>`_ include more
detail on this 'context manager' ability.
CDF objects behave like a python `dictionary
<http://docs.python.org/tutorial/datastructures.html#dictionaries>`_,
where the keys are names of variables in the CDF, and the values,
`Var` objects. As a dictionary, they are also `iterable
<http://docs.python.org/tutorial/classes.html#iterators>`_ and it is easy
to loop over all of the variables in a file. Some examples:
#. List the names of all variables in the open CDF ``cdffile``:
>>> cdffile.keys()
>>> for k in cdffile: #Alternate
... print(k)
#. Get a `Var` object for the variable named ``Epoch``:
>>> epoch = cdffile['Epoch']
#. Determine if a CDF contains a variable named ``B_GSE``:
>>> if 'B_GSE' in cdffile:
... print('B_GSE is in the file')
... else:
... print('B_GSE is not in the file')
#. Find how many variables are in the file:
>>> print(len(cdffile))
#. Delete the variable ``Epoch`` from the open CDF file ``cdffile``:
>>> del cdffile['Epoch']
#. Display a summary of variables and types in open CDF file ``cdffile``:
>>> print(cdffile)
#. Open the CDF named ``cdf_filename.cdf``, read *all* the data from
all variables into dictionary ``data``, and close it when done or
if an error occurs:
>>> with pycdf.CDF('cdf_filename.cdf') as cdffile:
... data = cdffile.copy()
This last example can be very inefficient as it reads the entire CDF.
Normally it's better to treat the CDF as a dictionary and access only
the data needed, which will be pulled transparently from disc. See
`Var` for more subtle examples.
Potentially useful dictionary methods and related functions:
- `in <http://docs.python.org/reference/expressions.html#in>`_
- `keys <http://docs.python.org/tutorial/datastructures.html#dictionaries>`_
- `len`
- `list comprehensions
<http://docs.python.org/tutorial/datastructures.html#list-comprehensions>`_
- `sorted`
- `~spacepy.toolbox.dictree`
The CDF user's guide section 2.2 has more background information on CDF
files.
The :attr:`~CDF.attrs` Python attribute acts as a dictionary
referencing CDF attributes (do not confuse the two); all the
dictionary methods above also work on the attribute dictionary.
See `gAttrList` for more on the dictionary of global
attributes.
Creating a new CDF from a master (skeleton) CDF has similar syntax to
opening one:
>>> cdffile = pycdf.CDF('cdf_filename.cdf', 'master_cdf_filename.cdf')
This creates and opens ``cdf_filename.cdf`` as a copy of
``master_cdf_filename.cdf``.
Using a skeleton CDF is recommended over making a CDF entirely from
scratch, but this is possible by specifying a blank master:
>>> cdffile = pycdf.CDF('cdf_filename.cdf', '')
When CDFs are created in this way, they are opened read-write, see
:meth:`readonly` to change.
By default, new CDFs (without a master) are created in version 3
format. To create a version 2 (backward-compatible) CDF, use
:meth:`Library.set_backward`:
>>> pycdf.lib.set_backward(True)
>>> cdffile = pycdf.CDF('cdf_filename.cdf', '')
Add variables by direct assignment, which will automatically set type
and dimension based on the data provided:
>>> cdffile['new_variable_name'] = [1, 2, 3, 4]
or, if more control is needed over the type and dimensions, use
:meth:`new`.
Although it is supported to assign Var objects to Python variables
for convenience, there are some minor pitfalls that can arise when
changing a CDF that will not affect most users. This is only a
concern when assigning a zVar object to a Python variable, changing the
CDF through some other variable, and then trying to use the zVar
object via the originally assigned variable.
Deleting a variable:
>>> var = cdffile['Var1']
>>> del cdffile['Var1']
>>> var[0] #fail, no such variable
Renaming a variable:
>>> var = cdffile['Var1']
>>> cdffile['Var1'].rename('Var2')
>>> var[0] #fail, no such variable
Renaming via the same variable works:
>>> var = cdffile['Var1']
>>> var.rename('Var2')
>>> var[0] #succeeds, aware of new name
Deleting a variable and then creating another variable with the same name
may lead to some surprises:
>>> var = cdffile['Var1']
>>> var[...] = [1, 2, 3, 4]
>>> del cdffile['Var1']
>>> cdffile.new('Var1', data=[5, 6, 7, 8]
>>> var[...]
[5, 6, 7, 8]
.. autosummary::
~CDF.attr_num
~CDF.attrs
~CDF.add_attr_to_cache
~CDF.add_to_cache
~CDF.backward
~CDF.checksum
~CDF.clear_attr_from_cache
~CDF.clear_from_cache
~CDF.clone
~CDF.close
~CDF.col_major
~CDF.compress
~CDF.copy
~CDF.from_data
~CDF.new
~CDF.raw_var
~CDF.readonly
~CDF.save
~CDF.var_num
~CDF.version
.. attribute:: CDF.attrs
Global attributes for this CDF in a dict-like format.
See `gAttrList` for details.
.. attribute:: CDF.backward
True if this CDF was created in backward-compatible mode
(for opening with CDF library before 3.x)
.. automethod:: add_to_cache
.. automethod:: add_attr_to_cache
.. automethod:: attr_num
.. automethod:: checksum
.. automethod:: clear_from_cache
.. automethod:: clear_attr_from_cache
.. automethod:: clone
.. automethod:: close
.. automethod:: col_major
.. automethod:: compress
.. automethod:: copy
.. automethod:: from_data
.. automethod:: new
.. automethod:: raw_var
.. automethod:: readonly
.. automethod:: save
.. automethod:: var_num
.. automethod:: version
"""
backward = False
"""True if this CDF was created in backward-compatible mode."""
def __init__(self, pathname, masterpath=None, create=None, readonly=None,
encoding='utf-8'):
"""Open or create a CDF file.
Parameters
==========
pathname : string
name of the file to open or create
masterpath : string
name of the master CDF file to use in creating
a new file. If not provided, an existing file is
opened; if provided but evaluates to ``False``
(e.g., ``''``), an empty new CDF is created.
create : bool
Create a new CDF even if masterpath isn't provided
readonly : bool
Open the CDF read-only. Default True if opening an
existing CDF; False if creating a new one.
encoding : str, optional
Text encoding to use when reading and writing strings.
Default ``'utf-8'``.
Raises
======
CDFError
if CDF library reports an error
CDFWarning
if CDF library reports a warning and interpreter
is set to error on warnings.
Examples
========
Open a CDF by creating a CDF object, e.g.:
>>> cdffile = pycdf.CDF('cdf_filename.cdf')
Be sure to :meth:`pycdf.CDF.close` or :meth:`pycdf.CDF.save`
when done.
"""
if masterpath is not None: #Looks like we want to create
if create is False:
raise ValueError('Cannot specify a master CDF without creating a CDF')
if readonly is True:
raise ValueError('Cannot create a CDF in readonly mode')
if create and readonly:
raise ValueError('Cannot create a CDF in readonly mode')
try:
self.pathname = pathname.encode()
except AttributeError:
raise ValueError(
'pathname must be string-like: {0}'.format(pathname))
self._handle = ctypes.c_void_p(None)
self._opened = False
self.encoding = encoding
if masterpath is None and not create:
self._open(True if readonly is None else readonly)
elif masterpath:
self._from_master(masterpath.encode())
self._check_enc()
else:
self._create()
self._check_enc()
lib.call(const.SELECT_, const.CDF_zMODE_, ctypes.c_long(2))
self._attrlistref = weakref.ref(gAttrList(self))
self.backward = self.version()[0] < 3
self._var_nums = {}
"""Cache of name-to-number mappings for variables in this CDF"""
self._attr_info = {}
"""Cache of name-to-(number, global) mappings for attributes
in this CDF"""
def __del__(self):
"""Destructor; called when CDF object is destroyed.
Close CDF file if there is still a valid handle.
.. note::
To avoid data loss, explicitly call :meth:`pycdf.CDF.close`
or :meth:`pycdf.CDF.save`.
"""
if self._opened:
self.close()
def __delitem__(self, name):
"""Delete a zVariable in this CDF, by name or number
Parameters
==========
name : string or int
Name or number of the CDF variable
.. note:
Variable numbers may change if variables are added or removed.
Examples
========
Delete the variable ``Epoch`` from the open CDF file ``cdffile``.
>>> del cdffile['Epoch']
"""
self[name]._delete()
def __enter__(self):
"""Context manager entrance function."""
return self
def __exit__(self, type, value, traceback):
"""Context manager exit function.
Close CDF file.
"""
self.close()
def __getitem__(self, name):
"""Gets a zVariable in this CDF, by name or number
The CDF acts like a dict
@param name: Name or number of the CDF variable
@type name: string or int
@return: CDF variable named or numbered L{name}
@rtype: `pycdf.Var`
@raise KeyError: for pretty much any problem in lookup
@note: variable numbers may change if variables are added or removed.
"""
try:
return Var(self, name)
except CDFException as e:
raise KeyError('{0}: {1}'.format(name, e))
def __setitem__(self, name, data):
"""Writes data to a zVariable in this CDF
If the zVariable does not exist, will create one matching
L{data}. If it does exist, will attempt to write L{data}
to it without changing the type or dimensions.
@param name: name or number of the variable to write
@type name: str or int
@param data: data to write, or a `pycdf.Var` to copy
"""
if isinstance(data, Var):
self.clone(data, name)
elif name in self:
self[name][...] = data
if hasattr(data, 'attrs'):
self[name].attrs.clone(data.attrs)
else:
self.new(name, data)
def __iter__(self, current = 0):
"""Iterates over zVars in CDF
Iterators for dicts return keys
@note: Returned in variable-number order
"""
while current < self.__len__():
name = self[current].name()
value = (yield name)
if value is None:
current += 1
else:
current = self[value]._num()
current += 1
def __len__(self):
"""Implements 'length' of CDF (number of zVars)
@return: number of zVars in the CDF
@rtype: int
"""
count = ctypes.c_long(0)
self._call(const.GET_, const.CDF_NUMzVARS_, ctypes.byref(count))
return count.value
def __contains__(self, key):
"""Determines whether a particular variable name is in the CDF
@note: Essentially an efficiency function; L{__iter__} is called
if this isn't defined
@param key: key/variable name to check
@type key: string
@return: True if L{key} is the name of a variable in CDF, else False
@rtype: Boolean
"""
if isinstance(key, str):
key = key.encode('ascii')
key = key.rstrip()
if key in self._var_nums:
return True
status = self._call(const.CONFIRM_, const.zVAR_EXISTENCE_, key,
ignore=(const.NO_SUCH_VAR,))
return status != const.NO_SUCH_VAR
def __repr__(self):
"""Returns representation of CDF
Cannot return anything that can be eval'd to create a copy of the
CDF, so just wrap the informal representation in angle brackets.
@return: all the data in this list of attributes
@rtype: str
"""
return '<CDF:\n' + str(self) + '\n>'
def __str__(self):
"""Returns a string representation of the CDF
This is an 'informal' representation in that it cannot be evaluated
directly to create a `pycdf.CDF`, just the names, types, and sizes of all
variables. (Attributes are not listed.)
@return: description of the variables in the CDF
@rtype: str
"""
if self._opened:
return '\n'.join([key + ': ' + str(value)
for (key, value) in sorted(self.items())])
#can get away with this sort because second value in tuple isn't
#compared unless first are different, and variable name is unique.
else:
if isinstance(self.pathname, str):
return 'Closed CDF {0}'.format(self.pathname)
else:
return 'Closed CDF {0}'.format(self.pathname.decode('ascii'))
def _open(self, readonly=True):
"""Opens the CDF file (called on init)
Will open an existing CDF file read/write.
Raises
======
CDFError : if CDF library reports an error
CDFWarning : if CDF library reports a warning and interpreter
is set to error on warnings.
.. note:
Not intended for direct call; pass parameters to
`pycdf.CDF` constructor.
"""
lib.call(const.OPEN_, const.CDF_, self.pathname, ctypes.byref(self._handle))
self._opened = True
if readonly: #Default is RW
self.readonly(readonly)
else:
self._check_enc()
def _create(self):
"""Creates (and opens) a new CDF file
Created at ``pathname``.
Assumes zero-dimension r variables
Raises
======
CDFError : if CDF library reports an error
CDFWarning : if CDF library reports a warning and interpreter
is set to error on warnings.
.. note:
Not intended for direct call; pass parameters to
`pycdf.CDF` constructor.
"""
lib.call(const.CREATE_, const.CDF_, self.pathname, ctypes.c_long(0),
(ctypes.c_long * 1)(0), ctypes.byref(self._handle))
self._opened = True
def _from_master(self, master_path):
"""Creates a new CDF from a master CDF file
``master_path`` is copied to ``pathname`` and opened.
Parameters
==========
master_path : string
location of the master CDF file
Raises
======
CDFError : if CDF library reports an error
CDFWarning : if CDF library reports a warning and interpreter
is set to error on warnings.
.. note:
Not intended for direct call; pass parameters to
`pycdf.CDF` constructor.
"""
if os.path.exists(self.pathname):
raise CDFError(const.CDF_EXISTS)
shutil.copy2(master_path, self.pathname)
self._open(False)
def _check_enc(self):
"""Check encoding and raise warning if nonstandard"""
if self.encoding not in ('ascii', 'utf-8'):
warnings.warn(
'Opening CDF for write with nonstandard encoding {}'.format(
self.encoding))
[docs] @classmethod
def from_data(cls, filename, sd):
"""Create a new CDF file from a SpaceData object or similar
The CDF named ``filename`` is created, opened, filled with the
contents of ``sd`` (including attributes), and closed.
``sd`` should be a dictionary-like object; each key will be made
into a variable name. An attribute called ``attrs``, if it exists,
will be made into global attributes for the CDF.
Each value of ``sd`` should be array-like and will be used as
the contents of the variable; an attribute called ``attrs``, if
it exists, will be made into attributes for that variable.
Parameters
----------
filename : string
name of the file to create
sd : spacepy.datamodel.SpaceData
data to put in the CDF. This structure cannot be nested,
i.e., it must contain only `~spacepy.datamodel.dmarray`
and no `~spacepy.datamodel.Spacedata` objects.
"""
with cls(filename, '') as cdffile:
for k in sd:
cdffile[k] = sd[k]
cdffile.attrs.clone(sd.attrs)
def _call(self, *args, **kwargs):
"""Select this CDF as current and call the CDF internal interface
Adds call to select this CDF to L{args} and passes all parameters
directly through to the CDFlib routine of the CDF library's C internal
interface. Checks the return value with L{Library.check_status}.
Parameters
==========
args : various, see `ctypes`.
Passed directly to the CDF library interface. Useful
constants are defined in the :doc:`const <pycdf_const>`
module of this package.
Returns
=======
out : ctypes.c_long
CDF status from the library
.. note:
Terminal NULL_ is automatically added to ``args``.
Raises
======
CDFError : if CDF library reports an error
CDFWarning : if CDF library reports a warning and interpreter
is set to error on warnings.
"""
return lib.call(const.SELECT_, const.CDF_, self._handle,
*args, **kwargs)
[docs] def clone(self, zVar, name=None, data=True):
"""
Clone a zVariable (from another CDF or this) into this CDF
Parameters
==========
zVar : `Var`
variable to clone
Other Parameters
================
name : str
Name of the new variable (default: name of the original)
data : boolean (optional)
Copy data, or only type, dimensions, variance, attributes?
(default: True, copy data as well)
Returns
=======
out : `Var`
The newly-created zVar in this CDF
"""
if name is None:
name = zVar.name()
if name in self:
del self[name]
self.new(name, type=zVar.type(), recVary=zVar.rv(),
dimVarys=zVar.dv(), dims=zVar._dim_sizes(),
n_elements=zVar.nelems())
self[name].compress(*zVar.compress())
self[name].attrs.clone(zVar.attrs)
if data:
r = zVar._raw
zVar._raw = True
self.raw_var(name)[...] = zVar[...]
zVar._raw = r
return zVar
[docs] def col_major(self, new_col=None):
"""
Finds the majority of this CDF file
Other Parameters
================
new_col : boolean
Specify True to change to column-major, False to change to
row major, or do not specify to check the majority
rather than changing it.
(default is check only)
Returns
=======
out : boolean
True if column-major, false if row-major
"""
if new_col != None:
new_maj = const.COLUMN_MAJOR if new_col else const.ROW_MAJOR
self._call(const.PUT_, const.CDF_MAJORITY_, new_maj)
maj = ctypes.c_long(0)
self._call(const.GET_, const.CDF_MAJORITY_, ctypes.byref(maj))
if not maj.value in (const.ROW_MAJOR.value, const.COLUMN_MAJOR.value):
raise CDFError(const.BAD_MAJORITY)
return maj.value == const.COLUMN_MAJOR.value
[docs] def readonly(self, ro=None):
"""
Sets or check the readonly status of this CDF
If the CDF has been changed since opening, setting readonly mode
will have no effect.
.. note::
Before version 3.8.1 of the NASA CDF library,
closing a CDF that has been opened readonly, or setting readonly
False, may take a substantial amount of time if there are many
variables in the CDF, as a (potentially large) cache needs to
be cleared. If upgrading to a newer CDF library is not possible,
specifying ``readonly=False`` when opening the file is an option.
However, this may make some reading operations slower.
Other Parameters
================
ro : Boolean
True to set the CDF readonly, False to set it read/write,
or leave out to check only.
Returns
=======
out : Boolean
True if CDF is read-only, else False
Raises
======
CDFError : if bad mode is set
"""
if ro == True:
self._call(const.SELECT_, const.CDF_READONLY_MODE_,
const.READONLYon)
elif ro == False:
self._call(const.SELECT_, const.CDF_READONLY_MODE_,
const.READONLYoff)
self._check_enc()
mode = ctypes.c_long(0)
self._call(const.CONFIRM_, const.CDF_READONLY_MODE_,
ctypes.byref(mode))
if mode.value == const.READONLYon.value:
return True
elif mode.value == const.READONLYoff.value:
return False
else:
raise CDFError(const.BAD_READONLY_MODE.value)
[docs] def checksum(self, new_val=None):
"""
Set or check the checksum status of this CDF. If checksums
are enabled, the checksum will be verified every time the file
is opened.
Other Parameters
================
new_val : boolean
True to enable checksum, False to disable, or leave out
to simply check.
Returns
=======
out : boolean
True if the checksum is enabled or False if disabled
"""
if new_val != None:
self._call(const.PUT_, const.CDF_CHECKSUM_,
const.MD5_CHECKSUM if new_val else const.NO_CHECKSUM)
chk = ctypes.c_long(0)
self._call(const.GET_, const.CDF_CHECKSUM_, ctypes.byref(chk))
if not chk.value in (const.MD5_CHECKSUM.value,
const.NO_CHECKSUM.value):
raise CDFError(const.BAD_CHECKSUM)
return chk.value == const.MD5_CHECKSUM.value
[docs] def close(self):
"""
Closes the CDF file
Although called on object destruction (:meth:`~CDF.__del__`),
to ensure all data are saved, the user should explicitly call
:meth:`~CDF.close` or :meth:`~CDF.save`.
Raises
======
CDFError : if CDF library reports an error
Warns
=====
CDFWarning : if CDF library reports a warning
"""
self._call(const.CLOSE_, const.CDF_)
self._opened = False
[docs] def compress(self, comptype=None, param=None):
"""
Set or check the compression of this CDF
Sets compression on entire *file*, not per-variable.
See section 2.6 of the CDF user's guide for more information on
compression.
Other Parameters
================
comptype : ctypes.c_long
type of compression to change to, see CDF C reference manual
section 4.10. Constants for this parameter are in
`~spacepy.pycdf.const`. If not specified, will not change
compression.
param : ctypes.c_long
Compression parameter, see CDF CRM 4.10 and
`~spacepy.pycdf.const`.
If not specified, will choose reasonable default (5 for gzip;
other types have only one possible parameter.)
Returns
=======
out : tuple
(comptype, param) currently in effect
See Also
========
:meth:`Var.compress`
Examples
========
Set file ``cdffile`` to gzip compression, compression level 9:
>>> cdffile.compress(pycdf.const.GZIP_COMPRESSION, 9)
"""
return _compress(self, comptype, param)
[docs] def new(self, name, data=None, type=None, recVary=None, dimVarys=None,
dims=None, n_elements=None, compress=None, compress_param=None,
sparse=None, pad=None):
"""Create a new zVariable in this CDF
.. note::
Either ``data`` or ``type`` must be specified. If type is not
specified, it is guessed from ``data``.
This creates a new variable. If using a "master CDF" with
existing variables and no records, simply assign the new data
to the variable, or the "whole variable" slice:
>>> cdf['ExistingVariable'] = data
>>> cdf['ExistingVariable'][...] = data
Parameters
==========
name : str
name of the new variable
Other Parameters
================
data
data to store in the new variable. If this has a an
``attrs`` attribute (e.g.,
`~spacepy.datamodel.dmarray`), it will be used to
populate attributes of the new variable. Similarly the CDF
type, record variance, etc. will, by default, be taken
from `data` if it is a
`~spacepy.pycdf.VarCopy`. This can be overridden by
specifying other keywords.
type : ctypes.c_long
CDF type of the variable, from `~spacepy.pycdf.const`.
See section 2.5 of the CDF user's guide for more information on
CDF data types.
recVary : boolean
record variance of the variable (default True)
dimVarys : list of boolean
dimension variance of each dimension, default True for all
dimensions.
dims : list of int
size of each dimension of this variable, default zero-dimensional.
Note this is the dimensionality as defined by CDF, i.e., for
record-varying variables it excludes the leading record dimension.
See `Var`.
n_elements : int
number of elements, should be 1 except for CDF_CHAR,
for which it's the length of the string.
compress : ctypes.c_long
Compression to apply to this variable, default None.
See :meth:`Var.compress`.
compress_param : ctypes.c_long
Compression parameter if compression used; reasonable default
is chosen. See :meth:`Var.compress`.
sparse : ctypes.c_long
.. versionadded:: 0.2.3
Sparse records type for this variable, default None (no sparse
records). See :meth:`Var.sparse`.
pad :
.. versionadded:: 0.2.3
Pad value for this variable, default None (do not set). See
:meth:`Var.pad`.
Returns
=======
out : `Var`
the newly-created zVariable
Raises
======
ValueError : if neither data nor sufficient typing information
is provided.
Notes
=====
Any given data may be representable by a range of CDF types; if
the type is not specified, pycdf will guess which
the CDF types which can represent this data. This breaks down to:
#. If input data is a numpy array, match the type of that array
#. Proper kind (numerical, string, time)
#. Proper range (stores highest and lowest number provided)
#. Sufficient resolution (EPOCH16 or TIME_TT2000 required if datetime
has microseconds or below.)
If more than one value satisfies the requirements, types are returned
in preferred order:
#. Type that matches precision of data first, then
#. integer type before float type, then
#. Smallest type first, then
#. signed type first, then
#. specifically-named (CDF_BYTE) vs. generically named (CDF_INT1)
TIME_TT2000 is always the preferred time type if it is available.
Otherwise, EPOCH_16 is preferred over EPOCH if ``data`` specifies
below the millisecond level (rule 1), but otherwise EPOCH is preferred
(rule 2).
.. versionchanged:: 0.3.0
Before 0.3.0, EPOCH or EPOCH_16 were used if not specified. Now
TIME_TT2000 is always the preferred type.
For floats, four-byte is preferred unless eight-byte is required:
#. absolute values between 0 and 3e-39
#. absolute values greater than 1.7e38
This will switch to an eight-byte double in some cases where four bytes
would be sufficient for IEEE 754 encoding, but where DEC formats would
require eight.
"""
if hasattr(data, 'compress'):
try:
c, cp = data.compress()
except: #numpy arrays have "compress" and it behaves differently
pass
else:
if compress is None:
compress = c
# Ignore data's compress_param if using compress argument
if compress_param is None:
compress_param = cp
if hasattr(data, 'sparse') and sparse is None:
sparse = data.sparse()
if hasattr(data, 'pad') and pad is None:
pad = data.pad()
#Get defaults from VarCopy if data looks like a VarCopy
if recVary is None:
recVary = data.rv() if hasattr(data, 'rv') else True
#Use dimension variance from the copy if it matches # of dims
if dimVarys is None and hasattr(data, 'dv') and hasattr(data, 'shape'):
dv = data.dv()
if len(dv) + int(recVary) == len(data.shape):
dimVarys = dv
if type in (const.CDF_EPOCH16, const.CDF_INT8, const.CDF_TIME_TT2000) \
and self.backward:
raise ValueError('Cannot use EPOCH16, INT8, or TIME_TT2000 '
'in backward-compatible CDF')
if data is None:
if type is None:
raise ValueError('Must provide either data or a CDF type.')
if dims is None:
dims = []
if n_elements is None:
n_elements = 1
else:
#This supports getting the type straight from a VarCopy
(guess_dims, guess_types, guess_elements)\
= _Hyperslice.types(data, encoding=self.encoding)
if dims is None:
if recVary:
if guess_dims == ():
raise ValueError(
'Record-varying data cannot be scalar. '
'Specify NRV with CDF.new() or put data in array.')
dims = guess_dims[1:]
else:
dims = guess_dims
if type is None:
type = guess_types[0]
if type in (const.CDF_EPOCH16.value,
const.CDF_TIME_TT2000.value) and self.backward:
type = const.CDF_EPOCH
if n_elements is None:
n_elements = guess_elements
if dimVarys is None:
dimVarys = [True for i in dims]
recVary = const.VARY if recVary else const.NOVARY
dimVarys = [const.VARY if dimVary else const.NOVARY
for dimVary in dimVarys]
if not hasattr(type, 'value'):
type = ctypes.c_long(type)
if type.value in (const.CDF_EPOCH16.value, const.CDF_INT8.value,
const.CDF_TIME_TT2000.value) \
and self.backward:
raise ValueError('Data requires EPOCH16, INT8, or TIME_TT2000; '
'incompatible with backward-compatible CDF')
new_var = Var(self, name, type, n_elements, dims, recVary, dimVarys)
if compress is not None:
new_var.compress(compress, compress_param)
if sparse is not None:
new_var.sparse(sparse)
if pad is not None:
new_var.pad(pad)
if data is not None:
new_var[...] = data
if hasattr(data, 'attrs'):
new_var.attrs.clone(data.attrs)
return new_var
[docs] def raw_var(self, name):
"""
Get a "raw" `Var` object.
Normally a `Var` will perform translation of values for
certain types (to/from Unicode for CHAR variables on Py3k,
and to/from datetime for all time types). A "raw" object
does not perform this translation, on read or write.
This does *not* affect the data on disk, and in fact it
is possible to maintain multiple Python objects with access
to the same zVariable.
Parameters
==========
name : str
name or number of the zVariable
"""
v = self[name]
v._raw = True
return v
[docs] def save(self):
"""
Saves the CDF file but leaves it open.
If closing the CDF, :meth:`close` is sufficient;
there is no need to call
:meth:`save` before :meth:`close`.
.. note::
Relies on an undocumented call of the CDF C library, which is
also used in the Java interface.
Raises
======
CDFError : if CDF library reports an error
Warns
=====
CDFWarning : if CDF library reports a warning
"""
self._call(const.SAVE_, const.CDF_)
[docs] def copy(self):
"""
Make a copy of all data and attributes in this CDF
Returns
=======
out : `CDFCopy`
`~spacepy.datamodel.SpaceData`-like object of all data
"""
return CDFCopy(self)
[docs] def version(self):
"""
Get version of library that created this CDF
Returns
=======
out : tuple
version of CDF library, in form (version, release, increment)
"""
ver = ctypes.c_long(0)
rel = ctypes.c_long(0)
inc = ctypes.c_long(0)
self._call(const.GET_, const.CDF_VERSION_, ctypes.byref(ver),
const.GET_, const.CDF_RELEASE_, ctypes.byref(rel),
const.GET_, const.CDF_INCREMENT_, ctypes.byref(inc))
return (ver.value, rel.value, inc.value)
def _get_attrs(self):
"""Get attribute list
Provide access to the CDF's attribute list without holding a
strong reference, as the attribute list has a (strong)
back-reference to its parent.
Either deref a weak reference (to try and keep the object the same),
or make a new AttrList instance and assign it to the weak reference
for next time.
"""
al = self._attrlistref()
if al is None:
al = gAttrList(self)
self._attrlistref = weakref.ref(al)
return al
def _set_attrs(self, value):
"""Assign to the attribute list
Clears all elements of the attribute list and copies from value
"""
self.attrs.clone(value)
attrs = property(
_get_attrs, _set_attrs, None,
"""Global attributes for this CDF in a dict-like format.
See `gAttrList` for details.
""")
[docs] def var_num(self, varname):
"""Get the variable number of a particular variable name
This maintains a cache of name-to-number mappings for zVariables
to keep from having to query the CDF library constantly. It's mostly
an internal function.
Parameters
==========
varname : bytes
name of the zVariable. Not this is NOT a string in Python 3!
Raises
======
CDFError : if variable is not found
Returns
=======
out : int
Variable number of this zvariable.
"""
num = self._var_nums.get(varname, None)
if num is None: #Copied from Var._get, which can hopefully be thinned
varNum = ctypes.c_long(0)
self._call(const.GET_, const.zVAR_NUMBER_, varname,
ctypes.byref(varNum))
num = varNum.value
self._var_nums[varname] = num
return num
[docs] def attr_num(self, attrname):
"""Get the attribute number and scope by attribute name
This maintains a cache of name-to-number mappings for attributes
to keep from having to query the CDF library constantly. It's mostly
an internal function.
Parameters
==========
attrname : bytes
name of the attribute. Not this is NOT a string in Python 3!
Raises
======
CDFError : if attribute is not found
Returns
=======
out : tuple
attribute number, scope (True for global) of this attribute
"""
res = self._attr_info.get(attrname, None)
if res is None: #Copied from Var._get, which can hopefully be thinned
attrNum = ctypes.c_long(0)
self._call(const.GET_, const.ATTR_NUMBER_, attrname,
ctypes.byref(attrNum))
scope = ctypes.c_long(0)
self._call(const.SELECT_, const.ATTR_, attrNum,
const.GET_, const.ATTR_SCOPE_, ctypes.byref(scope))
if scope.value == const.GLOBAL_SCOPE.value:
scope = True
elif scope.value == const.VARIABLE_SCOPE.value:
scope = False
else:
raise CDFError(const.BAD_SCOPE)
res = (attrNum.value, scope)
self._attr_info[attrname] = res
return res
[docs] def clear_attr_from_cache(self, attrname):
"""Mark an attribute deleted in the name-to-number cache
Will remove an attribute, and all attributes with higher numbers,
from the attribute cache.
Does NOT delete the variable!
This maintains a cache of name-to-number mappings for attributes
to keep from having to query the CDF library constantly. It's mostly
an internal function.
Parameters
==========
attrname : bytes
name of the attribute. Not this is NOT a string in Python 3!
"""
num, scope = self.attr_num(attrname)
#All numbers higher than this are renumbered
for a, n in list(self._attr_info.items()):
if n[0] >= num:
del self._attr_info[a]
[docs] def clear_from_cache(self, varname):
"""Mark a variable deleted in the name-to-number cache
Will remove a variable, and all variables with higher numbers,
from the variable cache.
Does NOT delete the variable!
This maintains a cache of name-to-number mappings for zVariables
to keep from having to query the CDF library constantly. It's mostly
an internal function.
Parameters
==========
varname : bytes
name of the zVariable. Not this is NOT a string in Python 3!
"""
num = self.var_num(varname)
#All numbers higher than this are renumbered
for v, n in list(self._var_nums.items()):
if n >= num:
del self._var_nums[v]
[docs] def add_attr_to_cache(self, attrname, num, scope):
"""Add an attribute to the name-to-number cache
This maintains a cache of name-to-number mappings for attributes
to keep from having to query the CDF library constantly. It's mostly
an internal function.
Parameters
==========
varname : bytes
name of the zVariable. Not this is NOT a string in Python 3!
num : int
number of the variable
scope : bool
True if global scope; False if variable scope.
"""
self._attr_info[attrname] = (num, scope)
[docs] def add_to_cache(self, varname, num):
"""Add a variable to the name-to-number cache
This maintains a cache of name-to-number mappings for zVariables
to keep from having to query the CDF library constantly. It's mostly
an internal function.
Parameters
==========
varname : bytes
name of the zVariable. Not this is NOT a string in Python 3!
num : int
number of the variable
"""
self._var_nums[varname] = num
#Note there is no function for delete, currently handled in Var.rename
#and Attr.rename by just deleting from the dict directly. Maybe this
#should be differen (maybe should be possible to follow a variable across
#a rename...)
[docs]class CDFCopy(spacepy.datamodel.SpaceData):
"""
A dictionary-like copy of all data and attributes in a `CDF`
Data are `VarCopy` objects, keyed by variable name.
CDF attributes are in :attr:`attrs`. (I.e.,
data are accessed much like from a `CDF`).
Do not instantiate this class directly; use :meth:`~CDF.copy`
on an existing `CDF`.
Examples
--------
>>> from spacepy import pycdf
>>> with pycdf.CDF('test.cdf') as cdffile:
... data = cdffile.copy()
.. attribute:: attrs
Python dictionary containing attributes copied from the CDF.
"""
def __init__(self, cdf):
"""Copies all data and attributes from a CDF
@param cdf: CDF to take data from
@type cdf: `pycdf.CDF`
"""
super(CDFCopy, self).__init__(((key, var.copy())
for (key, var) in cdf.items()),
attrs = cdf.attrs.copy())
[docs]def concatCDF(cdfs, varnames=None, raw=False):
"""Concatenate data from multiple CDFs
Reads data from all specified CDFs in order and returns as if they
were from a single CDF. The assumption is that the CDFs all have the
same structure (same variables, each with the same dimensions and
variance.)
Parameters
----------
cdfs : list of `~spacepy.pycdf.Var`
Open CDFs, will be read from in order. Must be a list (cannot
be an iterable, as all files need to be open).
varnames : list of str
Names of variables to read (default: all variables in first CDF)
raw : bool
If True, read variables as raw (don't convert epochs, etc.)
Default False.
Returns
-------
`~spacepy.datamodel.SpaceData`
data concatenated from each CDF, with all attributes from first.
Non-record-varying data is also only from first, and record
variance is only checked on the first!
Examples
--------
Read all data from all CDFs in the current directory. Note that
CDFs are closed when their variable goes out of scope.
>>> import glob
>>> import spacepy.pycdf
>>> data = spacepy.pycdf.concatCDF([
... spacepy.pycdf.CDF(f) for f in glob.glob('*.cdf')])
"""
if varnames is None:
varnames = list(cdfs[0].keys()) #Iterate over this CDF only once
vargetter = lambda f, v: f.raw_var(v) if raw else f[v]
return spacepy.datamodel.SpaceData(
{v:
spacepy.datamodel.dmarray(
numpy.concatenate([vargetter(f, v)[...] for f in cdfs]),
attrs=vargetter(cdfs[0], v).attrs.copy())
if cdfs[0][v].rv() else vargetter(cdfs[0], v).copy()
for v in varnames},
attrs=cdfs[0].attrs.copy())
[docs]class Var(MutableSequence, spacepy.datamodel.MetaMixin):
"""
A CDF variable.
This object does not directly store the data from the CDF; rather,
it provides access to the data in a format that much like a Python
list or numpy `~numpy.ndarray`.
General list information is available in the python docs:
`1 <http://docs.python.org/tutorial/introduction.html#lists>`_,
`2 <http://docs.python.org/tutorial/datastructures.html#more-on-lists>`_,
`3 <http://docs.python.org/library/stdtypes.html#typesseq>`_.
The CDF user's guide, section 2.3, provides background on variables.
.. note::
Not intended to be created directly; use methods of `CDF` to gain access to a variable.
A record-varying variable's data are viewed as a hypercube of dimensions
n_dims+1 (the extra dimension is the record number). They are indexed in
row-major fashion, i.e. the last index changes most frequently / is
contiguous in memory. If the CDF is column-major, the data are
transformed to row-major before return.
Non record-varying variables are similar, but do not have the extra
dimension of record number.
Variables can be subscripted by a multidimensional index to return the
data. Indices are in row-major order with the first dimension
representing the record number. If the CDF is column major,
the data are reordered to row major. Each dimension is specified
by standard Python
`slice <http://docs.python.org/tutorial/introduction.html#strings>`_
notation, with dimensions separated by commas. The ellipsis fills in
any missing dimensions with full slices. The returned data are
lists; Python represents multidimensional arrays as nested lists.
The innermost set of lists represents contiguous data.
.. note::
numpy 'fancy indexing' is *not* supported.
Degenerate dimensions are 'collapsed', i.e. no list of only one
element will be returned if a single subscript is specified
instead of a range. (To avoid this, specify a slice like 1:2,
which starts with 1 and ends before 2).
Two special cases:
1. requesting a single-dimension slice for a
record-varying variable will return all data for that
record number (or those record numbers) for that variable.
2. Requests for multi-dimensional variables may skip the record-number
dimension and simply specify the slice on the array itself. In that
case, the slice of the array will be returned for all records.
In the event of ambiguity (e.g., single-dimension slice on a one-dimensional
variable), case 1 takes priority.
Otherwise, mismatch between the number of dimensions specified in
the slice and the number of dimensions in the variable will cause
an :exc:`~exceptions.IndexError` to be thrown.
This all sounds very complicated but it is essentially attempting
to do the 'right thing' for a range of slices.
An unusual case is scalar (zero-dimensional) non-record-varying variables.
Clearly they cannot be subscripted normally. In this case, use the
``[...]`` syntax meaning 'access all data.':
>>> from spacepy import pycdf
>>> testcdf = pycdf.CDF('test.cdf', '')
>>> variable = testcdf.new('variable', recVary=False,
... type=pycdf.const.CDF_INT4)
>>> variable[...] = 10
>>> variable
<Var:
CDF_INT4 [] NRV
>
>>> variable[...]
10
Reading any empty non-record-varying variable will return an empty
with the same *number* of dimensions, but all dimensions will be
of zero length. The scalar is, again, a special case: due to the
inability to have a numpy array which is both zero-dimensional and empty,
reading an NRV scalar variable with no data will return an empty
one-dimensional array. This is really not recommended.
Variables with no records (RV) or no data (NRV) are considered to be
"false"; those with records or data written are considered to be
"true", allowing for an easy check of data existence:
>>> if testcdf['variable']:
>>> # do things that require data to exist
As a list type, variables are also `iterable
<http://docs.python.org/tutorial/classes.html#iterators>`_; iterating
over a variable returns a single complete record at a time.
This is all clearer with examples. Consider a variable ``B_GSM``, with
three elements per record (x, y, z components) and fifty records in
the CDF. Then:
1. ``B_GSM[0, 1]`` is the y component of the first record.
2. ``B_GSM[10, :]`` is a three-element list, containing x, y, and z
components of the 11th record. As a shortcut, if only one dimension
is specified, it is assumed to be the record number, so this
could also be written ``B_GSM[10]``.
3. ``B_GSM[...]`` reads all data for ``B_GSM`` and returns it as a
fifty-element list, each element itself being a three-element
list of x, y, z components.
Multidimensional example: consider fluxes stored as a function of
pitch angle and energy. Such a variable may be called Flux and
stored as a two-dimensional array, with the first dimension
representing (say) ten energy steps and the second, eighteen
pitch angle bins (ten degrees wide, centered from 5 to 175 degrees).
Assume 100 records stored in the CDF (i.e. 100 different times).
1. ``Flux[4]`` is a list of ten elements, one per energy step,
each element being a list of 18 fluxes, one per pitch bin.
All are taken from the fifth record in the CDF.
2. ``Flux[4, :, 0:4]`` is the same record, all energies, but
only the first four pitch bins (roughly, field-aligned).
3. ``Flux[..., 0:4]`` is a 100-element list (one per record),
each element being a ten-element list (one per energy step),
each containing fluxes for the first four pitch bins.
This slicing notation is very flexible and allows reading
specifically the desired data from the CDF.
.. note::
The C CDF library allows reading records which have not been
written to a file, returning a pad value. pycdf checks the
size of a variable and will raise `IndexError` for most
attempts to read past the end, except for variables with sparse
records. If these checks fail, a value is returned with a warning
``VIRTUAL_RECORD_DATA``. Please `open an issue
<https://github.com/spacepy/spacepy/issues/new>`_ if this
occurs for variables without sparse records. See pg. 39 and
following of the `CDF User's Guide
<https://cdf.gsfc.nasa.gov/html/cdf_docs.html>`_ for more on
virtual records.
All data are, on read, converted to appropriate Python data
types; EPOCH, EPOCH16, and TIME_TT2000 types are converted to
`~datetime.datetime`. Data are returned in numpy arrays.
.. note::
Although pycdf supports TIME_TT2000 variables, the Python
`~datetime.datetime` object does not support leap
seconds. Thus, on read, any seconds past 59 are truncated
to 59.999999 (59 seconds, 999 milliseconds, 999 microseconds).
Potentially useful list methods and related functions:
- `count <http://docs.python.org/tutorial/datastructures.html#more-on-lists>`_
- `in <http://docs.python.org/reference/expressions.html#in>`_
- `index <http://docs.python.org/tutorial/datastructures.html#more-on-lists>`_
- `len <http://docs.python.org/library/functions.html#len>`_
- `list comprehensions
<http://docs.python.org/tutorial/datastructures.html#list-comprehensions>`_
- `sorted <http://docs.python.org/library/functions.html#sorted>`_
The topic of array majority can be very confusing; good background material
is available at `IDL Array Storage and Indexing
<http://www.idlcoyote.com/misc_tips/colrow_major.html>`_. In brief,
*regardless of the majority stored in the CDF*, pycdf will always present
the data in the native Python majority, row-major order, also known as
C order. This is the default order in `NumPy
<http://docs.scipy.org/doc/numpy/reference/arrays.ndarray.html
#internal-memory-layout-of-an-ndarray>`_.
However, packages that render image data may expect it in column-major
order. If the axes seem 'swapped' this is likely the reason.
The :attr:`~Var.attrs` Python attribute acts as a dictionary referencing
zAttributes (do not confuse the two); all the dictionary methods above
also work on the attribute dictionary. See `zAttrList` for more on
the dictionary of attributes.
With writing, as with reading, every attempt has been made to match the
behavior of Python lists. You can write one record, many records, or even
certain elements of all records. There is one restriction: only the record
dimension (i.e. dimension 0) can be resized by write, as all records
in a variable must have the same dimensions. Similarly, only whole
records can be deleted.
.. note::
Unusual error messages on writing data usually mean that pycdf is
unable to interpret the data as a regular array of a single type
matching the type and shape of the variable being written.
A 5x4 array is supported; an irregular array where one row has
five columns and a different row has six columns is not. Error messages
of this type include:
- ``Data must be well-formed, regular array of number, string, or datetime``
- ``setting an array element with a sequence.``
- ``shape mismatch: objects cannot be broadcast to a
single shape``
For these examples, assume Flux has 100 records and dimensions [2, 3].
Rewrite the first record without changing the rest:
>>> Flux[0] = [[1, 2, 3], [4, 5, 6]]
Writes a new first record and delete all the rest:
>>> Flux[...] = [[1, 2, 3], [4, 5, 6]]
Write a new record in the last position and add a new record after:
>>> Flux[99:] = [[[1, 2, 3], [4, 5, 6]],
... [[11, 12, 13], [14, 15, 16]]]
Insert two new records between the current number 5 and 6:
>>> Flux[5:6] = [[[1, 2, 3], [4, 5, 6]], [[11, 12, 13],
... [14, 15, 16]]]
This operation can be quite slow, as it requires reading and
rewriting the entire variable. (CDF does not directly support
record insertion.)
Change the first element of the first two records but leave other
elements alone:
>>> Flux[0:2, 0, 0] = [1, 2]
Remove the first record:
>>> del Flux[0]
Removes record 5 (the sixth):
>>> del Flux[5]
Delete *all data* from ``Flux``, but leave the variable definition intact:
>>> del Flux[...]
.. note::
Variables using sparse records do not support insertion and only
support deletion of a single record at a time. See
:meth:`~Var.sparse` and section 2.3.12 of the CDF user's guide for
more information on sparse records.
.. note::
Although this interface only directly supports zVariables, zMode is
set on opening the CDF so rVars appear as zVars. See p.24 of the
CDF user's guide; pyCDF uses zMode 2.
.. autosummary::
~Var.attrs
~Var.compress
~Var.copy
~Var.dtype
~Var.dv
~Var.insert
~Var.name
~Var.nelems
~Var.pad
~Var.rename
~Var.rv
~Var.shape
~Var.sparse
~Var.type
.. attribute:: Var.attrs
zAttributes for this zVariable in a dict-like format.
See `zAttrList` for details.
.. automethod:: compress
.. automethod:: copy
.. autoattribute:: dtype
.. automethod:: dv
.. automethod:: insert
.. automethod:: name
.. automethod:: nelems
.. automethod:: pad
.. automethod:: rename
.. automethod:: rv
.. autoattribute:: shape
.. automethod:: sparse
.. automethod:: type
"""
def __init__(self, cdf_file, var_name, *args):
"""Create or locate a variable
Parameters
==========
cdf_file : `pycdf.CDF`
CDF file containing this variable
var_name : string
name of this variable
Other Parameters
================
args
additional arguments passed to :meth:`_create`. If none,
opens an existing variable. If provided, creates a
new one.
Raises
======
CDFError
if CDF library reports an error
Warns
=====
CDFWarning
if CDF library reports a warning
"""
self.cdf_file = cdf_file
#This is the definitive "identify" of variable
self._name = None
self._type = None #CDF type (long)
self._raw = False #Raw access (skip all conversions)
if len(args) == 0:
self._get(var_name)
else:
self._create(var_name, *args)
#Weak reference to attribute list (use attrs instead)
#This avoids a reference loop
self._attrlistref = weakref.ref(zAttrList(self))
def __getitem__(self, key):
"""Returns a slice from the data array. Details under `pycdf.Var`.
@return: The data from this variable
@rtype: list-of-lists of appropriate type.
@raise IndexError: if L{key} is out of range, mismatches dimensions,
or simply unparseable.
@raise CDFError: for errors from the CDF library
"""
hslice = _Hyperslice(self, key)
#Hyperslice mostly catches this sort of thing, but
#an empty variable is a special case, since we might want to
#WRITE to 0th record (which Hyperslice also supports) but
#can't READ from it, and iterating over tries to read from it.
if hslice.rv:
if hslice.dimsizes[0] == 0 and hslice.degen[0] and \
hslice.starts[0] == 0:
raise IndexError('record index out of range')
#For NRV, again hslice will assume 0th record exists since we might
#want to write. So ANY degenerate dim other than the glued-on 0th
#suggests an explicit index that should fail. None degenerate suggests
#make an empty array.
#Note this is pulling a lot of hyperslice stuff into getitem!
elif hslice.dimsizes[0] == 0:
if len(hslice.degen) > 1 and max(hslice.degen[1:]):
raise IndexError('record index out of range')
else:
#The zero-length dimension is degenerate so it gets chopped,
#and you can't have a zero-length numpy array that still
#maintains the size of all other dimensions. So just force
#a zero-dim array and the rest will follow
hslice.counts[...] = 0
#If this is a scalar, need to make a single non-degenerate
#dimension so it can be empty.
if len(hslice.counts) == 1:
hslice.degen[0] = False
result = hslice.create_array()
if hslice.counts[0] != 0:
hslice.select()
lib.call(const.GET_, const.zVAR_HYPERDATA_,
result.ctypes.data_as(ctypes.c_void_p))
return hslice.convert_input_array(result)
def __delitem__(self, key):
"""Removes a record (or set of records) from the CDF
Only whole records can be deleted, so the del call must either specify
only one dimension or it must specify all elements of the non-record
dimensions. This is *not* a way to resize a variable!
@param key: index or slice to delete
@type key: int or slice
@raise TypeError: if an attempt is made to delete from a non
record-varying variable, or to delete below
the record level
"""
if not self.rv():
raise TypeError('Cannot delete records from non-record-varying '
'variable.')
hslice = _Hyperslice(self, key)
if hslice.dims > 1 and (hslice.counts[1:] != hslice.dimsizes[1:]).any():
raise TypeError('Can only delete entire records.')
if hslice.counts[0] == 0:
return
if hslice.sr and not hslice.degen[0]:
raise NotImplementedError(
'Sparse records do not support multi-record delete.')
start = hslice.starts[0]
count = hslice.counts[0]
interval = hslice.intervals[0]
dimsize = hslice.dimsizes[0]
self._call()
if interval == 1:
first_rec = ctypes.c_long(start)
last_rec = ctypes.c_long(start + count - 1)
lib.call(const.DELETE_, const.zVAR_RECORDS_,
first_rec, last_rec)
else:
self._call()
#delete from end to avoid renumbering of records
for recno in range(start + (count - 1) * interval,
start - 1, -1 * interval):
lib.call(const.DELETE_, const.zVAR_RECORDS_,
ctypes.c_long(recno), ctypes.c_long(recno))
def _prepare(self, data):
"""Convert data to numpy array for writing to CDF
Converts input data intended for CDF writing into a numpy array,
so the array's buffer can be used directly for the output buffer
Parameters
==========
data : various
data to write
Returns
=======
numpy.ndarray
`data` converted, including time conversions
"""
cdf_type = self.type()
np_type = self._np_type()
if cdf_type == const.CDF_EPOCH16.value:
if not self._raw:
try:
data = lib.v_datetime_to_epoch16(data)
except AttributeError:
pass
np_type = numpy.float64
elif cdf_type == const.CDF_EPOCH.value:
if not self._raw:
try:
data = lib.v_datetime_to_epoch(data)
except AttributeError:
pass
elif cdf_type == const.CDF_TIME_TT2000.value:
if not self._raw:
try:
data = lib.v_datetime_to_tt2000(data)
except AttributeError:
pass
elif cdf_type in (const.CDF_UCHAR.value, const.CDF_CHAR.value):
if not self._raw:
data = numpy.asanyarray(data)
if data.dtype.kind == 'U':
data = numpy.char.encode(
data, encoding=self.cdf_file.encoding)
data = numpy.require(data, requirements=('C', 'A', 'W'),
dtype=np_type)
return data
def __setitem__(self, key, data):
"""Puts a slice into the data array. Details under `pycdf.Var`.
@param key: index or slice to store
@type key: int or slice
@param data: data to store
@type data: numpy.array
@raise IndexError: if L{key} is out of range, mismatches dimensions,
or simply unparseable. IndexError will
@raise CDFError: for errors from the CDF library
"""
hslice = _Hyperslice(self, key)
n_recs = hslice.counts[0]
hslice.expand(data)
cdf_type = self.type()
data = self._prepare(data)
if cdf_type == const.CDF_EPOCH16.value:
datashape = data.shape[:-1]
else:
datashape = data.shape
#Check data sizes
if datashape != tuple(hslice.expected_dims()):
raise ValueError('attempt to assign data of dimensions ' +
str(datashape) + ' to slice of dimensions ' +
str(tuple(hslice.expected_dims())))
#Flip majority and reversed dimensions, see convert_input_array
data = hslice.convert_output_array(data)
#Handle insertions and similar weirdness
if hslice.counts[0] > n_recs and \
hslice.starts[0] + n_recs < hslice.dimsizes[0]:
#Specified slice ends before last record, so insert in middle
if hslice.sr:
raise NotImplementedError(
'Sparse records do not support insertion.')
saved_data = self[hslice.starts[0] + n_recs:]
if hslice.counts[0] > 0:
hslice.select()
lib.call(const.PUT_, const.zVAR_HYPERDATA_,
data.ctypes.data_as(ctypes.c_void_p))
if hslice.counts[0] < n_recs:
if hslice.sr:
raise NotImplementedError(
'Sparse records do not support truncation on write.')
first_rec = hslice.starts[0] + hslice.counts[0]
last_rec = hslice.dimsizes[0] - 1
lib.call(const.DELETE_, const.zVAR_RECORDS_,
ctypes.c_long(first_rec), ctypes.c_long(last_rec))
elif hslice.counts[0] > n_recs and \
hslice.starts[0] + n_recs < hslice.dimsizes[0]:
#Put saved data in after inserted data
self[hslice.starts[0] + hslice.counts[0]:] = saved_data
def extend(self, data):
"""
Append multiple values to the end of this variable
This is an efficiency function which overrides the base implementation
in MutableSequence.
Parameters
----------
data :
the data to append
"""
self[len(self):] = data
[docs] def insert(self, index, data):
"""
Inserts a *single* record before an index
Parameters
----------
index : int
index before which to insert the new record
data :
the record to insert
"""
self[index:index] = [data]
def _create(self, var_name, datatype, n_elements = 1, dims = (),
recVary = const.VARY, dimVarys = None):
"""Creates a new zVariable
@param var_name: name of this variable
@type var_name: string
@param datatype: CDF data type
@type datatype: ctypes.c_long
@param n_elements: number of elements (should be 1 except for
CDF_CHAR variables).
@type n_elements: long
@param dims: size of each dimension for multi-dimensional variable,
or empty for a zero-dimensional
@type dims: sequence of long
@param recVary: record variance for this variable (VARY/NOVARY)
@type recVary: long
@param dimVarys: array of VARY or NOVARY, variance for each dimension
@type dimVarys: sequence of long
@return: new variable with this name
@rtype: `pycdf.Var`
@raise CDFError: if CDF library reports an error
@raise CDFWarning: if CDF library reports a warning and interpreter
is set to error on warnings.
@note: Not intended to be used directly; use L{CDF.new}.
"""
dim_array = (ctypes.c_long * len(dims))(*dims)
enc_name = var_name.encode('ascii')
if dimVarys is None:
dim_vary_array = (ctypes.c_long * (len(dims) if len(dims) > 0 else 1))(const.VARY)
else:
dim_vary_array = (ctypes.c_long * len(dims))(*dimVarys)
varNum = ctypes.c_long(0)
self.cdf_file._call(const.CREATE_, const.zVAR_, enc_name, datatype,
ctypes.c_long(n_elements), ctypes.c_long(len(dims)), dim_array,
recVary, dim_vary_array, ctypes.byref(varNum))
self._name = enc_name
self.cdf_file.add_to_cache(enc_name, varNum.value)
def _delete(self):
"""Removes this zVariable from the CDF
@raise CDFError: if CDF library reports an error
@raise CDFWarning: if CDF library reports a warning and interpreter
is set to error on warnings.
"""
self._call(const.DELETE_, const.zVAR_)
self.cdf_file.clear_from_cache(self._name)
self._name = None
def _get(self, var_name):
"""Gets an existing zVariable
@param var_name: name of this variable
@type var_name: string
@return: variable with this name
@rtype: `pycdf.Var`
@raise CDFError: if CDF library reports an error
@raise CDFWarning: if CDF library reports a warning and interpreter
is set to error on warnings.
@note: Not intended to be used directly; use L{CDF.__getitem__}.
"""
if isinstance(var_name, str_classes):
try:
enc_name = var_name.encode('ascii').rstrip()
except AttributeError:
enc_name = var_name.rstrip() #already in ASCII
#'touch' CDF to cause an error if the name isn't there; get number
varNum = ctypes.c_long(0)
self.cdf_file._call(const.GET_, const.zVAR_NUMBER_, enc_name, ctypes.byref(varNum))
self._name = enc_name
self.cdf_file.add_to_cache(enc_name, varNum.value)
else: #Looking up by number
name = ctypes.create_string_buffer(const.CDF_VAR_NAME_LEN256+1)
self.cdf_file._call(const.SELECT_, const.zVAR_, ctypes.c_long(var_name),
const.GET_, const.zVAR_NAME_, name)
self._name = name.value.rstrip()
self.cdf_file.add_to_cache(self._name, var_name)
def _num(self):
"""Returns the zVar number for this variable
@return: number of this zVar
@rtype: int
"""
return self.cdf_file.var_num(self._name)
def __len__(self):
"""Get number of records for this variable in this file
@return: Number of records
@rtype: long
@raise CDFError: if CDF library reports an error
@raise CDFWarning: if CDF library reports a warning and interpreter
is set to error on warnings.
"""
count = ctypes.c_long(0)
self._call(const.GET_, const.zVAR_MAXREC_, ctypes.byref(count))
return (count.value + 1)
def __repr__(self):
"""Returns representation of the variable
Cannot return anything that can be eval'd to create a copy,
so just wrap the informal representation in angle brackets.
@return: info on this zVar
@rtype: str
"""
return '<Var:\n' + str(self) + '\n>'
def __str__(self):
"""Returns a string representation of the variable
This is an 'informal' representation in that it cannot be evaluated
directly to create a `pycdf.Var`.
@return: info on this zVar, CDFTYPE [dimensions] NRV
(if not record-varying)
@rtype: str
"""
if self.cdf_file._opened:
cdftype = self.type()
chartypes = (const.CDF_CHAR.value, const.CDF_UCHAR.value)
rv = self.rv()
typestr = lib.cdftypenames[cdftype] + \
('*' + str(self.nelems()) if cdftype in chartypes else '' )
if rv:
sizestr = str([len(self)] + self._dim_sizes())
else:
sizestr = str(self._dim_sizes())
return typestr + ' ' + sizestr + ('' if rv else ' NRV')
else:
if isinstance(self._name, str):
return 'zVar "{0}" in closed CDF {1}'.format(
self._name, self.cdf_file.pathname)
else:
return 'zVar "{0}" in closed CDF {1}'.format(
self._name.decode('ascii'),
self.cdf_file.pathname.decode('ascii'))
def _n_dims(self):
"""Get number of dimensions for this variable
@return: the number of dimensions
@rtype: long
"""
n_dims = ctypes.c_long(0)
self._call(const.GET_, const.zVAR_NUMDIMS_, ctypes.byref(n_dims))
return n_dims.value
def _dim_sizes(self):
"""Get the dimension sizes for this variable
@return: sequence of sizes
@rtype: sequence of long
@note: This will always be in Python order (i.e. row major, last index
iterates most quickly), *regardless* of the majority of the CDF.
"""
sizes = (ctypes.c_long * const.CDF_MAX_DIMS)(0)
self._call(const.GET_, const.zVAR_DIMSIZES_, sizes)
sizes = sizes[0:self._n_dims()]
return sizes
[docs] def rv(self, new_rv=None):
"""
Gets or sets whether this variable has record variance
If the variance is unknown, True is assumed
(this replicates the apparent behavior of the CDF library on
variable creation).
Other Parameters
================
new_rv : boolean
True to change to record variance, False to change to NRV,
unspecified to simply check variance.
Returns
=======
out : Boolean
True if record varying, False if NRV
"""
if new_rv != None:
self._call(const.PUT_, const.zVAR_RECVARY_,
const.VARY if new_rv else const.NOVARY)
vary = ctypes.c_long(0)
self._call(const.GET_, const.zVAR_RECVARY_, ctypes.byref(vary))
return vary.value != const.NOVARY.value
[docs] def sparse(self, sparsetype=None):
"""
Gets or sets this variable's sparse records mode.
Sparse records mode may not be changeable on variables with data
already written; even deleting the data may not permit the change.
See section 2.3.12 of the CDF user's guide for more information on
sparse records.
Other Parameters
================
sparsetype : ctypes.c_long
If specified, should be a sparse record mode from
`~spacepy.pycdf.const`; see also CDF C reference manual
section 4.11.1. If not specified, the sparse record mode for this
variable will not change.
Returns
=======
out : ctypes.c_long
Sparse record mode for this variable.
Notes
=====
.. versionadded:: 0.2.3
"""
valid_sr = [
const.NO_SPARSERECORDS,
const.PREV_SPARSERECORDS,
const.PAD_SPARSERECORDS
]
if sparsetype is not None:
if not hasattr(sparsetype, 'value'):
comptype = ctypes.c_long(sparsetype)
self._call(const.PUT_, const.zVAR_SPARSERECORDS_, sparsetype)
sr = ctypes.c_long(0)
self._call(const.GET_, const.zVAR_SPARSERECORDS_, ctypes.byref(sr))
values = {v.value : v for v in valid_sr}
return values[sr.value]
[docs] def pad(self, value=None):
"""
Gets or sets this variable's pad value.
See section 2.3.20 of the CDF user's guide for more information on
pad values.
Other Parameters
================
value :
If specified, should be an appropriate pad value. If not
specified, the pad value will not be set or changed.
Returns
=======
out :
Current pad value for this variable. ``None`` if it has never been
set. This rarely happens; the pad value is usually set by the CDF
library on variable creation.
Notes
=====
.. versionadded:: 0.2.3
"""
if value is not None:
data = self._prepare(value)
self._call(const.PUT_, const.zVAR_PADVALUE_,
data.ctypes.data_as(ctypes.c_void_p))
# Prepare buffer for return, to get array of correct type
# pretend it's [0, 0, 0, 0...] of the variable
hslice = _Hyperslice(self, (0,)*(self._n_dims() + int(self.rv())))
result = hslice.create_array()
status = self._call(const.GET_, const.zVAR_PADVALUE_,
result.ctypes.data_as(ctypes.c_void_p),
ignore=(const.NO_PADVALUE_SPECIFIED,))
if status == const.NO_PADVALUE_SPECIFIED:
return None
return hslice.convert_input_array(result)
[docs] def dv(self, new_dv=None):
"""
Gets or sets dimension variance of each dimension of variable.
If the variance is unknown, True is assumed
(this replicates the apparent behavior of the
CDF library on variable creation).
Parameters
==========
new_dv : list of boolean
Each element True to change that dimension to dimension
variance, False to change to not dimension variance.
(Unspecified to simply check variance.)
Returns
=======
out : list of boolean
True if that dimension has variance, else false.
"""
ndims = self._n_dims()
if new_dv != None:
if len(new_dv) != ndims:
raise ValueError('Must specify variance for ' +
str(ndims) + 'dimensions.')
varies = (ctypes.c_long * ndims)(
*[const.VARY if dv else const.NOVARY for dv in new_dv])
self._call(const.PUT_, const.zVAR_DIMVARYS_,
varies)
if ndims == 0:
return []
varies = (ctypes.c_long * const.CDF_MAX_DIMS)()
self._call(const.GET_, const.zVAR_DIMVARYS_, varies)
return [dv != const.NOVARY.value for dv in varies[0:ndims]]
def _call(self, *args, **kwargs):
"""Select this CDF and variable and call the CDF internal interface
Adds call to select this CDF to L{args} and passes all parameters
directly through to the CDFlib routine of the CDF library's C internal
interface. Checks the return value with L{Library.check_status}.
@param args: Passed directly to the CDF library interface. Useful
constants are defined in the `pycdf.const` module of this package.
@type args: various, see `ctypes`.
@return: CDF status from the library
@rtype: ctypes.c_long
@note: Terminal NULL_ is automatically added to L{args}.
@raise CDFError: if CDF library reports an error
@raise CDFWarning: if CDF library reports a warning and interpreter
is set to error on warnings.
"""
return self.cdf_file._call(
const.SELECT_, const.zVAR_,
ctypes.c_long(self.cdf_file.var_num(self._name)), *args, **kwargs)
def _np_type(self):
"""Returns the numpy type of this variable
This is the numpy type that will come directly out of the CDF;
see :meth:`dtype` for the representation post-conversion.
Raises
======
CDFError : for library-reported error or failure to find numpy type
Returns
=======
out : dtype
numpy dtype that will hold value from this variable
"""
cdftype = self.type()
if cdftype == const.CDF_CHAR.value or cdftype == const.CDF_UCHAR.value:
return numpy.dtype('S' + str(self.nelems()))
try:
return lib.numpytypedict[cdftype]
except KeyError:
raise CDFError(const.BAD_DATA_TYPE)
[docs] def type(self, new_type=None):
"""
Returns or sets the CDF type of this variable
Parameters
==========
new_type : ctypes.c_long
the new type from `~spacepy.pycdf.const`
Returns
=======
out : int
CDF type
"""
if new_type != None:
if not hasattr(new_type, 'value'):
new_type = ctypes.c_long(new_type)
n_elements = ctypes.c_long(self.nelems())
self._call(const.PUT_, const.zVAR_DATASPEC_,
new_type, n_elements)
self._type = None
if self._type is None:
cdftype = ctypes.c_long(0)
self._call(const.GET_, const.zVAR_DATATYPE_,
ctypes.byref(cdftype))
self._type = cdftype.value
return self._type
[docs] def nelems(self):
"""Number of elements for each value in this variable
This is the length of strings for CHAR and UCHAR,
should be 1 otherwise.
Returns
=======
int
length of strings
"""
nelems = ctypes.c_long(0)
self._call(const.GET_, const.zVAR_NUMELEMS_, ctypes.byref(nelems))
return nelems.value
[docs] def name(self):
"""
Returns the name of this variable
Returns
=======
out : str
variable's name
"""
if isinstance(self._name, str):
return self._name
elif isinstance(self._name, bytes):
return self._name.decode()
[docs] def compress(self, comptype=None, param=None):
"""
Set or check the compression of this variable
Compression may not be changeable on variables with data already
written; even deleting the data may not permit the change.
See section 2.6 of the CDF user's guide for more information on
compression.
Other Parameters
================
comptype : ctypes.c_long
type of compression to change to, see CDF C reference
manual section 4.10. Constants for this parameter
are in `~spacepy.pycdf.const`. If not specified, will not
change compression.
param : ctypes.c_long
Compression parameter, see CDF CRM 4.10 and
`~spacepy.pycdf.const`.
If not specified, will choose reasonable default (5 for
gzip; other types have only one possible parameter.)
Returns
=======
out : tuple
the (comptype, param) currently in effect
"""
return _compress(self, comptype, param)
[docs] def copy(self):
"""
Copies all data and attributes from this variable
Returns
=======
out : `VarCopy`
list of all data in record order
"""
return VarCopy(self)
[docs] def rename(self, new_name):
"""
Renames this variable
Parameters
==========
new_name : str
the new name for this variable
"""
try:
enc_name = new_name.encode('ascii')
except AttributeError:
enc_name = new_name
if len(enc_name) > const.CDF_VAR_NAME_LEN256:
raise CDFError(const.BAD_VAR_NAME)
self._call(const.PUT_, const.zVAR_NAME_, enc_name)
self.cdf_file.add_to_cache(
enc_name,
self.cdf_file.var_num(self._name)) #Still in cache
del self.cdf_file._var_nums[self._name]
self._name = enc_name
@property
def shape(self):
"""
Provides the numpy array-like shape of this variable.
Returns a tuple; first element is number of records (RV variable
only) And the rest provide the dimensionality of the variable.
.. note::
Assigning to this attribute will not change the shape.
"""
if self.rv():
return tuple([len(self)] + self._dim_sizes())
else:
return tuple(self._dim_sizes())
@property
def dtype(self):
"""
Provide the numpy dtype equivalent to the CDF type of this variable.
Data from this variable will be returned in numpy arrays of this type.
See Also
--------
type
"""
cdftype = self.type()
if cdftype in (const.CDF_CHAR.value, const.CDF_UCHAR.value) and \
not self._raw:
return numpy.dtype('U' + str(self.nelems()))
if cdftype in (const.CDF_EPOCH.value, const.CDF_EPOCH16.value,
const.CDF_TIME_TT2000.value) and not self._raw:
return numpy.dtype('O')
return self._np_type()
def _get_attrs(self):
"""Get attribute list
Provide access to the zVar's attribute list without holding a
strong reference, as the attribute list has a (strong)
back-reference to its parent.
Either deref a weak reference (to try and keep the object the same),
or make a new AttrList instance and assign it to the weak reference
for next time.
"""
al = self._attrlistref()
if al is None:
al = zAttrList(self)
self._attrlistref = weakref.ref(al)
return al
def _set_attrs(self, value):
"""Assign to the attribute list
Clears all elements of the attribute list and copies from value
"""
self.attrs.clone(value)
attrs = property(
_get_attrs, _set_attrs, None,
"""zAttributes for this zVariable in a dict-like format.
See `zAttrList` for details.
""")
[docs]class VarCopy(spacepy.datamodel.dmarray):
"""A list-like copy of the data and attributes in a `Var`
Data are in the list elements. CDF attributes are in a dict,
accessed through :attr:`attrs`. (I.e.,
data and attributes are accessed like in a `Var`.)
Do not instantiate this class directly; use :meth:`~Var.copy`
on an existing `Var`.
Several methods provide access to details about how the original
variable was constructed. This is mostly for making it easier to
reproduce the variable by passing it to
:meth:`~spacepy.pycdf.CDF.new`. Operations that e.g. change the
dimensionality of the copy may make this (or any) metadata out of
date; see :meth:`set` to update.
.. autosummary::
compress
dv
nelems
pad
rv
set
sparse
type
.. attribute:: attrs
Python dictionary containing attributes copied from the zVar
.. automethod:: compress
.. automethod:: dv
.. automethod:: nelems
.. automethod:: pad
.. automethod:: rv
.. automethod:: set
.. automethod:: sparse
.. automethod:: type
"""
Allowed_Attributes = spacepy.datamodel.dmarray.Allowed_Attributes \
+ ['_cdf_meta']
def __new__(cls, zVar):
"""Copies all data and attributes from a zVariable
@param zVar: variable to take data from
@type zVar: `pycdf.Var`
"""
obj = super(VarCopy, cls).__new__(cls, zVar[...], zVar.attrs.copy())
obj._cdf_meta = { k: getattr(zVar, k)() for k in (
'compress', 'dv', 'nelems', 'rv', 'sparse', 'type') }
obj._cdf_meta['pad'] = zVar.pad() if obj._cdf_meta['rv'] else None
return obj
[docs] def compress(self, *args, **kwargs):
"""Gets compression of the variable this was copied from.
For details on CDF compression, see
:meth:`spacepy.pycdf.Var.compress`.
If any arguments are specified, calls
:meth:`numpy.ndarray.compress` instead (as the names conflict)
Returns
=======
tuple
compression type, parameter currently in effect.
"""
if args or kwargs:
return super(VarCopy, self).compress(*args, **kwargs)
else:
return self._cdf_meta['compress']
[docs] def dv(self):
"""Gets dimension variance of the variable this was copied from.
Each dimension other than the record dimension may either vary
or not.
Returns
=======
list of boolean
True if that dimension has variance, else False
"""
return self._cdf_meta['dv']
[docs] def nelems(self):
"""Gets number of elements of the variable this was copied from.
This is usually 1 except for strings, where it is the length of the
string.
Returns
=======
int
Number of elements in parent variable
"""
return self._cdf_meta['nelems']
[docs] def pad(self):
"""Gets pad value of the copied variable.
This copy does *not* preserve which records were written, i.e.
the entire copy is read, including pad values, and the pad values
are treated as real data (if, e.g. writing to another CDF).
For details on padding, see :meth:`spacepy.pycdf.Var.pad`.
Returns
=======
various
Pad value, matching type of the variable.
Notes
=====
.. versionadded:: 0.2.3
"""
return self._cdf_meta['pad']
[docs] def rv(self):
"""Gets record variance of the variable this was copied from.
Returns
=======
boolean
True if parent variable was record varying, False if NRV
"""
return self._cdf_meta['rv']
[docs] def set(self, key, value):
"""Set CDF metadata
Set the metadata describing the original variable this was
copied from. Can be used to update the metadata if
transformation of the copy has made it out of date (e.g. by
removing dimensions.) There is very little checking done and
this function should only be used with care.
Parameters
==========
key : str
Which metadata to set; this matches the name of the method
used to retrieve it (e.g. use ``type`` to set the CDF type, which
is returned by :meth:`type`).
value
Value to assign to `key`.
"""
if key not in self._cdf_meta:
raise KeyError('Invalid CDF metadata key {}'.format(key))
self._cdf_meta[key] = value
[docs] def sparse(self):
"""Gets sparse records mode of the copied variable.
This copy does *not* preserve which records were written, i.e.
the entire copy is read, including pad values, and the pad values
are treated as real data (if, e.g. writing to another CDF).
For details on sparse records, see :meth:`spacepy.pycdf.Var.sparse`.
Returns
=======
ctypes.c_long
Sparse record type
Notes
=====
.. versionadded:: 0.2.3
"""
return self._cdf_meta['sparse']
[docs] def type(self):
"""Returns CDF type of the variable this was copied from.
Returns
=======
int
CDF type
"""
return self._cdf_meta['type']
class _Hyperslice(object):
"""Represents a CDF 'slice' used for the hyper CDF functions
For internal module use only.
@ivar dims: number of dimensions to this slice, usually
number of dimensions to the variable plus one
for the record, which represents the 0th
(least rapidly varying) dimension.
@type dims: int
@ivar dimsizes: size of each dimension (0th is number of records)
@type dimsizes: list of int
@ivar starts: index of the start value for each dimension
('dimension indices' in CDF speak)
@type starts: list of int
@ivar counts: number of values to get from each dimension.
Final result will be the product of everything
in counts.
('dimension counts' in CDF speak)
@type counts: numpy.array
@ivar intervals: interval between successive indices
to use for each dimension.
('dimension invervals' in CDF speak)
@type intervals: list of int
@ivar degen: is this dimension degenerate, i.e. should be
removed in the returned dataset. A 3D array
with one dimension degenerate will be returned
as a 2D array (i.e. list-of-lists.)
@type degen: numpy.array
@ivar rev: should this dimension be returned in reverse order?
@type rev: numpy.array
@ivar column: is this slice in column-major mode (if false, row-major)
@type column: boolean
@ivar zvar: what CDF variable this object slices on
@type zvar: `pycdf.Var`
@ivar expanded_key: fully-expanded version of the key passed to the
constructor (all dimensions filled in)
@type expanded_key: tuple
@note: All dimension-related variables are stored row-major
(Python order)
"""
def __init__(self, zvar, key):
"""Create a Hyperslice
@param zvar: zVariable that this slices
@type zvar: `pycdf.Var`
@param key: Python multi-dimensional slice as passed to
__getitem__
@type key: tuple of slice and/or int
@raise IndexError: if slice is out of range, mismatches dimensions, or
otherwise unparsable.
@raise ValueError: if slice has invalid values
"""
self.zvar = zvar
self.rv = self.zvar.rv()
self.sr = self.zvar.sparse() != const.NO_SPARSERECORDS
#dim of records, + 1 record dim (NRV always is record 0)
self.dims = zvar._n_dims() + 1
self.dimsizes = [len(zvar)] + \
zvar._dim_sizes()
self.starts = [0] * self.dims
self.counts = numpy.empty((self.dims,), dtype=numpy.int32)
self.counts.fill(1)
self.intervals = [1] * self.dims
self.degen = numpy.zeros(self.dims, dtype=bool)
self.rev = numpy.zeros(self.dims, dtype=bool)
#key is:
#1. a single value (integer or slice object) if called 1D
#2. a tuple (of integers and/or slice objects) if called nD
#3. Each item is either a single value (degenerate dim)
# or a slice object.
if not hasattr(key, '__len__'): #Not a container object, pack in tuple
key = (key, )
if not self.rv:
key = (0, ) + key #NRV, so always get 0th record (degenerate)
key = self.expand_ellipsis(key, self.dims)
if self.rv: #special-cases for RV variables
if len(key) == 1: #get all data for this record(s)
key = self.expand_ellipsis(key + (Ellipsis, ), self.dims)
elif len(key) == self.dims - 1: #get same slice from each record
key = (slice(None, None, None), ) + key
if len(key) == self.dims:
self.expanded_key = key
for i in range(self.dims):
idx = key[i]
if hasattr(idx, 'start'): #slice
# Allow read-off-end for record dim if sparse
off_end = self.sr and idx.stop is not None \
and idx.stop > self.dimsizes[i] and i == 0
(self.starts[i], self.counts[i],
self.intervals[i], self.rev[i]) = \
self.convert_range(
idx.start, idx.stop, idx.step,
idx.stop if off_end else self.dimsizes[i])
else: #Single degenerate value
if idx < 0:
idx += self.dimsizes[i]
out_of_range = idx < 0 or \
(idx >= self.dimsizes[i] and not self.sr)
if idx != 0 and out_of_range:
raise IndexError('list index out of range')
self.starts[i] = idx
self.degen[i] = True
else:
raise IndexError('Slice does not match dimensions for zVar ' +
str(zvar._name))
self.column = zvar.cdf_file.col_major()
def expected_dims(self, data=None):
"""Calculate size of non-degenerate dimensions
Figures out size, in each dimension, of expected input data
@return: size of each dimension for this slice, excluding degenerate
@rtype: list of int
"""
return [self.counts[i] for i in range(self.dims) if not self.degen[i]]
def expand(self, data):
"""Expands the record dimension of this slice to hold a set of data
If the length of data (outermost dimension) is larger than the record
count (counts[0]) for this slice, expand the slice to hold all the data.
This requires that the record dimension of the slice not be degenerate,
and also that it not have been completely specified when the hyperslice
was created (i.e. record dimension either ellipsis or no specified
stop.)
Does *not* expand any other dimension, since that's Very Hard in CDF.
@param data: the data which are intended to be stored in this slice
@type data: list
"""
rec_slice = self.expanded_key[0]
if not self.rv or isinstance(data, str_classes) or self.degen[0] or \
not hasattr(rec_slice, 'stop'):
return
if len(data) < self.counts[0]: #Truncate to fit data
if rec_slice.stop is None and rec_slice.step in (None, 1):
self.counts[0] = len(data)
elif len(data) > self.counts[0]: #Expand to fit data
if rec_slice.step in (None, 1):
self.counts[0] = len(data)
def create_array(self):
"""Creates a numpy array to hold the data from this slice
Returns
=======
out : numpy.array
array sized, typed, and dimensioned to hold data from
this slice
"""
counts = self.counts
degen = self.degen
if self.column:
counts = self.reorder(counts)
degen = self.reorder(degen)
#TODO: Forcing C order for now, revert to using self.column later
array = numpy.empty(
[counts[i] for i in range(len(counts)) if not degen[i]],
self.zvar._np_type(), order='C')
return numpy.require(array, requirements=('C', 'A', 'W'))
def convert_input_array(self, buffer):
"""Converts a buffer of raw data from this slice
EPOCH(16) variables always need to be converted.
CHAR need converted to Unicode if py3k
Parameters
==========
buffer : numpy.array
data as read from the CDF file
Returns
=======
out : numpy.array
converted data
"""
result = self._flip_array(buffer)
#Convert to derived types
cdftype = self.zvar.type()
if not self.zvar._raw:
if cdftype in (const.CDF_CHAR.value, const.CDF_UCHAR.value):
dt = numpy.dtype('U{0}'.format(result.dtype.itemsize))
result = numpy.require(
numpy.char.array(result).decode(
encoding=self.zvar.cdf_file.encoding, errors='replace'),
dtype=dt)
elif cdftype == const.CDF_EPOCH.value:
result = lib.v_epoch_to_datetime(result)
elif cdftype == const.CDF_EPOCH16.value:
result = lib.v_epoch16_to_datetime(result)
elif cdftype == const.CDF_TIME_TT2000.value:
result = lib.v_tt2000_to_datetime(result)
if getattr(result, 'shape', None) == ():
result = result.item()
return result
def convert_output_array(self, buffer):
"""Convert a buffer of data that will go into this slice
Parameters
==========
buffer : numpy.array
data to go into the CDF file
Returns
=======
out : numpy.array
input with majority flipped and dimensions reversed to be
suitable to pass directly to CDF library.
"""
buffer = self._flip_array(buffer)
return numpy.require(buffer, requirements=('C', 'A', 'W'))
def _flip_array(self, data):
"""
Operations for majority, etc. common between convert_input and _output
"""
cdftype = self.zvar.type()
#Flip majority if any non-degenerate dimensions exist
if self.column and not min(self.degen):
#Record-number dim degen, swap whole thing
if self.degen[0]:
if cdftype == const.CDF_EPOCH16.value:
#Maintain last dimension
data = data.transpose(
list(range(len(data.shape) - 2, 0, -1)) +
[len(data.shape) - 1]
)
else:
data = data.transpose()
#Record-number dimension is not degenerate, so keep it first
else:
if cdftype == const.CDF_EPOCH16.value:
data = data.transpose(
[0] + list(range(len(data.shape) - 2, 0, -1)) +
[len(data.shape) - 1]
)
else:
data = data.transpose(
[0] + list(range(len(data.shape) - 1, 0, -1)))
#Reverse non-degenerate dimensions in rev
#Remember that the degenerate indices are already gone!
if self.rev.any():
sliced = [(slice(None, None, -1) if self.rev[i] else slice(None))
for i in range(self.dims) if not self.degen[i]]
if cdftype == const.CDF_EPOCH16.value: #don't reverse last dim
sliced.extend(slice(None))
data = operator.getitem(data, tuple(sliced))
return data
def select(self):
"""Selects this hyperslice in the CDF
Calls the CDF library to select the CDF, variable, records, and
array elements corresponding to this slice.
"""
args = (const.SELECT_, const.zVAR_RECNUMBER_, ctypes.c_long(self.starts[0]),
const.SELECT_, const.zVAR_RECCOUNT_, ctypes.c_long(self.counts[0]),
const.SELECT_, const.zVAR_RECINTERVAL_,
ctypes.c_long(self.intervals[0]))
if self.dims > 1:
dims = self.dims - 1
args += (const.SELECT_, const.zVAR_DIMINDICES_,
(ctypes.c_long * dims)(*self.starts[1:]),
const.SELECT_, const.zVAR_DIMCOUNTS_,
(ctypes.c_long * dims)(*self.counts[1:]),
const.SELECT_, const.zVAR_DIMINTERVALS_,
(ctypes.c_long * dims)(*self.intervals[1:]))
self.zvar._call(*args)
@staticmethod
def expand_ellipsis(slices, n_dims):
"""Expands any ellipses into correct number of full-size slices
@param slices: tuple of slices, integers, or ellipse objects
@type slices: tuple
@param n_dims: number of dimensions this slice is over
@type n_dims: int
@return: L{slices} with ellipses replaced by appropriate number of
full-dimension slices
@rtype: tuple
@raise IndexError: if ellipses specified when already have enough
dimensions
"""
if slices is Ellipsis:
return tuple([slice(None, None, None)
for i in range(n_dims)])
#Elements might be numpy arrays, so can't use in/index
idx = [i for i, v in enumerate(slices) if v is Ellipsis]
if not idx: #no ellipsis
return slices
if len(idx) > 1: #multiples!
raise IndexError('Ellipses can only be used once per slice.')
idx = idx[0]
#how many dims to expand ellipsis to
#remember the ellipsis is in len(slices) and must be replaced!
extra = n_dims - len(slices) + 1
if extra < 0:
raise IndexError('too many indices')
result = slices[0:idx] + (slice(None), ) * extra + slices[idx+1:]
return result
@staticmethod
def check_well_formed(data):
"""Checks if input data is well-formed, regular array
Returns
-------
`~numpy.ndarray`
The input data as a well-formed array; may be the input
data exactly.
"""
msg = 'Data must be well-formed, regular array of number, '\
'string, or datetime'
try:
d = numpy.asanyarray(data)
except ValueError:
raise ValueError(msg)
# In a future numpy, the case tested below will raise ValueError,
# so can remove entire if block.
if d.dtype == object: #this is probably going to be bad
if d.shape != () and not len(d):
#Completely empty, so "well-formed" enough
return d
if numpy.array(d.flat[0]).shape != ():
# Sequence-like, so we know it's ragged
raise ValueError(msg)
return d
@staticmethod
def dimensions(data):
"""Finds the dimensions of a nested list-of-lists
@param data: data of which dimensions are desired
@type data: list (of lists)
@return: dimensions of L{data}, in order outside-in
@rtype: list of int
@raise ValueError: if L{data} has irregular dimensions
"""
return _Hyperslice.check_well_formed(data).shape
@staticmethod
def types(data, backward=False, encoding='utf-8'):
"""Find dimensions and valid types of a nested list-of-lists
Any given data may be representable by a range of CDF types; infer
the CDF types which can represent this data. This breaks down to:
1. Proper kind (numerical, string, time)
2. Proper range (stores highest and lowest number)
3. Sufficient resolution (EPOCH16 or TT2000 required if datetime has
microseconds or below.)
If more than one value satisfies the requirements, types are returned
in preferred order:
1. Type that matches precision of data first, then
2. integer type before float type, then
3. Smallest type first, then
4. signed type first, then
5. specifically-named (CDF_BYTE) vs. generically named (CDF_INT1)
So for example, EPOCH_16 is preferred over EPOCH if L{data} specifies
below the millisecond level (rule 1), but otherwise EPOCH is preferred
(rule 2). TIME_TT2000 is always preferred as of 0.3.0.
For floats, four-byte is preferred unless eight-byte is required:
1. absolute values between 0 and 3e-39
2. absolute values greater than 1.7e38
This will switch to an eight-byte double in some cases where four bytes
would be sufficient for IEEE 754 encoding, but where DEC formats would
require eight.
@param data: data for which dimensions and CDF types are desired
@type data: list (of lists)
@param backward: limit to pre-CDF3 types
@type backward: bool
@param encoding: Encoding to use for Unicode input, default utf-8
@type backward: str
@return: dimensions of L{data}, in order outside-in;
CDF types which can represent this data;
number of elements required (i.e. length of longest string)
@rtype: 3-tuple of lists ([int], [ctypes.c_long], [int])
@raise ValueError: if L{data} has irregular dimensions
"""
d = _Hyperslice.check_well_formed(data)
dims = d.shape
elements = 1
types = []
if d.dtype.kind in ('S', 'U'): #it's a string
types = [const.CDF_CHAR, const.CDF_UCHAR]
# Length of string from type (may be longer than contents)
elements = d.dtype.itemsize
if d.dtype.kind == 'U':
# Big enough for contents (bytes/char are encoding-specific)
elements = max(
elements // 4, # numpy stores as 4-byte
numpy.char.encode(d, encoding=encoding).dtype.itemsize)
elif d.size and hasattr(numpy.ma.getdata(d).flat[0], 'microsecond'):
if max((dt.microsecond % 1000 for dt in d.flat)) > 0:
types = [const.CDF_TIME_TT2000, const.CDF_EPOCH16,
const.CDF_EPOCH]
else:
types = [const.CDF_TIME_TT2000, const.CDF_EPOCH,
const.CDF_EPOCH16]
if backward:
del types[types.index(const.CDF_EPOCH16)]
del types[0]
elif d is data or isinstance(data, numpy.generic):
#numpy array came in, use its type (or byte-swapped)
types = [k for k in lib.numpytypedict
if (lib.numpytypedict[k] == d.dtype
or lib.numpytypedict[k] == d.dtype.newbyteorder())
and not k in lib.timetypes]
if backward \
and const.CDF_INT8.value in types:
del types[types.index(const.CDF_INT8.value)]
#Maintain priority to match the ordered lists below:
#float/double (44, 45) before real (21/22), and
#byte (41) before int (1) before char (51). So hack.
#Consider making typedict an ordered dict once 2.6 is dead.
types.sort(key=lambda x: x % 50, reverse=True)
if not types: #not a numpy array, or can't parse its type
if d.dtype.kind == 'O': #Object. Try to make it numeric
if d.shape != () and not len(d):
raise ValueError(
'Cannot determine CDF type of empty object array.')
#Can't do safe casting from Object, so try and compare
#Basically try most restrictive to least restrictive
trytypes = (numpy.uint64, numpy.int64, numpy.float64)
for t in trytypes:
try:
newd = d.astype(dtype=t)
except: #Failure to cast, try next type
continue
if (newd == d).all(): #Values preserved, use this type
d = newd
#Continue with normal guessing, as if a list
break
else:
#fell through without a match
raise ValueError(
'Cannot convert generic objects to CDF type.')
if d.dtype.kind in ('i', 'u'): #integer
minval = numpy.min(d)
maxval = numpy.max(d)
if minval < 0:
types = [const.CDF_BYTE, const.CDF_INT1,
const.CDF_INT2, const.CDF_INT4, const.CDF_INT8,
const.CDF_FLOAT, const.CDF_REAL4,
const.CDF_DOUBLE, const.CDF_REAL8]
cutoffs = [2 ** 7, 2 ** 7, 2 ** 15, 2 ** 31, 2 ** 63,
1.7e38, 1.7e38, 8e307, 8e307]
else:
types = [const.CDF_BYTE, const.CDF_INT1, const.CDF_UINT1,
const.CDF_INT2, const.CDF_UINT2,
const.CDF_INT4, const.CDF_UINT4,
const.CDF_INT8,
const.CDF_FLOAT, const.CDF_REAL4,
const.CDF_DOUBLE, const.CDF_REAL8]
cutoffs = [2 ** 7, 2 ** 7, 2 ** 8,
2 ** 15, 2 ** 16, 2 ** 31, 2 ** 32, 2 ** 63,
1.7e38, 1.7e38, 8e307, 8e307]
types = [t for (t, c) in zip(types, cutoffs) if c > maxval
and (minval >= 0 or minval >= -c)]
if backward and const.CDF_INT8 in types:
del types[types.index(const.CDF_INT8)]
else: #float
if dims == ():
if d != 0 and (abs(d) > 1.7e38 or abs(d) < 3e-39):
types = [const.CDF_DOUBLE, const.CDF_REAL8]
else:
types = [const.CDF_FLOAT, const.CDF_REAL4,
const.CDF_DOUBLE, const.CDF_REAL8]
else:
absolutes = numpy.abs(d[d != 0])
if len(absolutes) > 0 and \
(numpy.max(absolutes) > 1.7e38 or
numpy.min(absolutes) < 3e-39):
types = [const.CDF_DOUBLE, const.CDF_REAL8]
else:
types = [const.CDF_FLOAT, const.CDF_REAL4,
const.CDF_DOUBLE, const.CDF_REAL8]
types = [t.value if hasattr(t, 'value') else t for t in types]
#If data has a type, might be a VarCopy, prefer that type
if hasattr(data, 'type'):
try:
t = data.type()
except:
t = None
pass
if t in types:
types = [t]
#If passed array, types prefers its dtype, so try for compatible
#and let type() override
elif d is data:
try:
_ = data.astype(dtype=lib.numpytypedict[t])
except:
pass
finally:
types = [t]
#And if the VarCopy specifies a number of elements, use that
#if compatible
if hasattr(data, 'nelems'):
ne = data.nelems()
if ne > elements:
elements = ne
return (dims, types, elements)
@staticmethod
def reorder(seq):
"""Reorders seq to switch array majority
Used to take an array of subscripts between row
and column majority. First element is not touched,
being the record number.
@param seq: a sequence of *subscripts*
@type seq: sequence of integers
@return: seq with all but element 0 reversed in order
@rtype: sequence of integers
"""
return numpy.concatenate((seq[0:1],
numpy.flipud(seq)[:-1]))
@staticmethod
def convert_range(start, stop, step, size):
"""Converts a start/stop/step range to start/count/interval
(i.e. changes from Python-style slice to CDF-style)
@param start: index to start a slice at, may be none or negative
@type start: int
@param stop: index at end of slice (one-past, standard Python),
may be none or negative
@type stop: int
@param step: interval for stepping through stlice
@type step: int
@param size: size of list to slice
@type size: int
@return: (start, count, interval, rev) where:
1. start is the start index, normalized to be within
the size of the list and negatives handled
2. count is the number of records in the slice,
guaranteed to stop before the end
3. interval is the skip between records
4. rev indicates whether the sequence should be reversed
@rtype: (int, int, int, boolean)
"""
(start, stop, step) = slice(start, stop, step).indices(size)
if step < 0:
step *= -1
count = int((start - stop + step - 1) / step)
start = start - (count - 1) * step
rev = True
else:
count = int((stop - start + step - 1) / step)
rev = False
if count < 0:
count = 0
start = 0
return (start, count, step, rev)
[docs]class Attr(MutableSequence):
"""An attribute, g or z, for a CDF
.. warning::
This class should not be used directly, but only in its
subclasses, `gAttr` and `zAttr`. The methods
listed here are safe to use in the subclasses.
Represents a CDF attribute, providing access to the Entries in a format
that looks like a Python
list. General list information is available in the python docs:
`1 <http://docs.python.org/tutorial/introduction.html#lists>`_,
`2 <http://docs.python.org/tutorial/datastructures.html#more-on-lists>`_,
`3 <http://docs.python.org/library/stdtypes.html#typesseq>`_.
An introduction to CDF attributes can be found in section 2.4 of
the CDF user's guide.
Each element of the list is a single Entry of the appropriate type.
The index to the elements is the Entry number.
Multi-dimensional slicing is *not* supported; an Entry with multiple
elements will have all elements returned (and can thus be sliced itself).
Example:
>>> first_three = attribute[5, 0:3] #will fail
>>> first_three = attribute[5][0:3] #first three elements of 5th Entry
.. autosummary::
~Attr.append
~Attr.has_entry
~Attr.insert
~Attr.max_idx
~Attr.new
~Attr.number
~Attr.rename
~Attr.type
.. automethod:: append
.. automethod:: has_entry
.. automethod:: insert
.. automethod:: max_idx
.. automethod:: new
.. automethod:: number
.. automethod:: rename
.. automethod:: type
"""
def __init__(self, cdf_file, attr_name, create=False):
"""Initialize this attribute
@param cdf_file: CDF file containing this attribute
@type cdf_file: `pycdf.CDF`
@param attr_name: Name of this attribute
@type attr_name: str
@param create: True to create attribute, False to look up existing.
@type create: bool
"""
self._cdf_file = cdf_file
self._raw = False
if isinstance(attr_name, str_classes):
try:
self._name = attr_name.encode('ascii')
except AttributeError:
self._name = attr_name
attrno = ctypes.c_long()
if create:
self._cdf_file._call(const.CREATE_, const.ATTR_,
self._name, self.SCOPE,
ctypes.byref(attrno))
self._cdf_file.add_attr_to_cache(
self._name, attrno.value, self.SCOPE == const.GLOBAL_SCOPE)
else: #Ensure exists, and populate cache. See scope note below
attrno, scope = self._cdf_file.attr_num(self._name)
else:
name = ctypes.create_string_buffer(const.CDF_ATTR_NAME_LEN256 + 1)
scope = ctypes.c_long(0)
self._cdf_file._call(const.SELECT_, const.ATTR_,
ctypes.c_long(attr_name))
#Because it's possible to create a gAttr Python object
#referencing an Attribute with variable scope, and vice-versa,
#do NOT assume the scope matches
#(Higher level code checks for that being a bad thing.)
self._cdf_file._call(
const.GET_, const.ATTR_NAME_, name,
const.GET_, const.ATTR_SCOPE_, ctypes.byref(scope))
self._name = name.value.rstrip()
if scope.value == const.GLOBAL_SCOPE.value:
scope = True
elif scope.value == const.VARIABLE_SCOPE.value:
scope = False
else:
raise CDFError(const.BAD_SCOPE)
self._cdf_file.add_attr_to_cache(self._name, attr_name, scope)
def __getitem__(self, key):
"""Return a slice of Entries.
Because Attributes may be sparse, a multi-element slice will return
None for those elements which do not have associated Entries.
@param key: index or range of Entry number to return
@type key: slice or int
@return: a list of entries, appropriate type.
@raise IndexError: if L{key} is an int and that Entry number does not
exist.
"""
if key is Ellipsis:
key = slice(None, None, None)
if hasattr(key, 'indices'):
idx = range(*key.indices(self.max_idx() + 1))
return [self._get_entry(i) if self.has_entry(i) else None
for i in idx]
else:
if self.has_entry(key):
return self._get_entry(key)
else:
raise IndexError('list index ' + str(key) + ' out of range.')
def _check_other_entries(self, types):
"""Try to get the type of this entry from others in the Attribute
For zAttrs, checks if all other Entries are the same type, and at
least one doesn't match its zVar, i.e. Entry type dominates (otherwise
assumption is the Var type dominates).
For gAttrs, checks all other Entries, and gives priority to the
one that's earliest in the possible type list and exists in other
Entries.
This is only one component of Entry type guessing!
:param list types: CDF types that are candidates (match the data)
:return: The type discerned from other Entries, or None
"""
if self.ENTRY_ == const.zENTRY_:
#If everything else is the same entry type,
#and one is not the same as its var, probably
#all entries should be of that type
cand_et = None #The Entry type that might work
one_var_diff = False #One Var has a type different from Entry
for num in range(self.max_idx() + 1):
if not self.has_entry(num):
continue
vartype = self._cdf_file[num].type()
entrytype = self.type(num)
if vartype != entrytype:
one_var_diff = True
if cand_et is None:
if not entrytype in types:
return None #One var has Entry with "impossible" type
cand_et = entrytype
elif cand_et != entrytype:
return None #Two vars have Entries with different types
if one_var_diff and cand_et is not None:
return cand_et
else:
# Of those types which exist in other entries,
# find the one which is earliest
# in types, i.e. the preferred type
entrytypes = [self.type(num) for num in
range(self.max_idx() + 1)
if self.has_entry(num)]
entrytypes = [et for et in entrytypes if et in types]
if entrytypes:
return types[
min([types.index(et) for et in entrytypes])]
return None
def __setitem__(self, key, data):
"""Set a slice of Entries.
@param key: index or range of Entry numbers to set
@type key: slice or int
@param data: the data to set these entries to. Normally each entry should
be a sequence; if a scalar is provided, it is treated
as a single-element list.
@type data: scalar or list
@raise ValueError: if size of {data} does not match size of L{key}
@note: Attributes do not 'grow' or 'shrink' as entries are added
or removed. Indexes of entries never change and there is no
way to 'insert'.
"""
if key is Ellipsis:
key = slice(None, None, None)
if not hasattr(key, 'indices'):
#Single value, promote everything a dimension
idx = (key, key + 1, 1)
data = [data]
else:
idx = key.indices(self.max_idx() + 1)
if key.step is None or key.step > 0:
#Iterating forward, extend slice to match data
if len(data) > len(range(*idx)):
idx = (idx[0], idx[0] + idx[2] * len(data), idx[2])
#get, and check, types and sizes for all data
#checks first so don't have error after changing half the Entries
data_idx = -1
typelist = []
for i in range(*idx):
data_idx += 1
if data_idx >= len(data):
continue
datum = data[data_idx]
if datum is None:
typelist[i] = (None, None, None)
continue
(dims, types, elements) = _Hyperslice.types(
datum, backward=self._cdf_file.backward,
encoding=self._cdf_file.encoding)
if len(types) <= 0:
raise ValueError('Cannot find a matching CDF type.')
if len(dims) > 1:
raise ValueError('Entries must be scalar or 1D.')
elif len(dims) == 1 and isinstance(datum[0], str_classes):
raise ValueError('Entry strings must be scalar.')
entry_type = None
if self.has_entry(i): #If the entry already exists, match its type
entry_type = self.type(i)
if not entry_type in types:
entry_type = None
if entry_type is None: #Check other entries for this attribute
entry_type = self._check_other_entries(types)
if entry_type is None and self.ENTRY_ == const.zENTRY_:
#Fall back to zVar type
vartype = self._cdf_file[i].type()
if vartype in types:
entry_type = vartype
if entry_type is None:
entry_type = types[0]
if not entry_type in lib.numpytypedict:
raise ValueError('Cannot find a matching numpy type.')
typelist.append((dims, entry_type, elements))
data_idx = -1
for i in range(*idx):
data_idx += 1
if data_idx >= len(data) or data[data_idx] is None:
if self.has_entry(i):
del self[i]
continue
datum = data[data_idx]
(dims, entry_type, elements) = typelist[data_idx]
self._write_entry(i, datum, entry_type, dims, elements)
def __delitem__(self, key):
"""Delete a slice of Entries.
@param key: index or range of Entry numbers to delete
@type key: slice or int
@note: Attributes do not 'grow' or 'shrink' as entries are added
or removed. Indexes of entries never change and there is no
way to 'insert'.
"""
if key is Ellipsis:
key = slice(None, None, None)
if not hasattr(key, 'indices'):
idx = (key, key + 1, 1)
else:
idx = key.indices(self.max_idx() + 1)
for i in range(*idx):
self._call(const.SELECT_, self.ENTRY_, ctypes.c_long(i),
const.DELETE_, self.ENTRY_)
def __iter__(self, current=0):
"""Iterates over all entries in this Attribute
Returns data from one entry at a time until reaches the end.
@note: Returned in entry-number order.
"""
while current <= self.max_idx():
if self.has_entry(current):
value = yield(self._get_entry(current))
if value != None:
current = value
current += 1
def __reversed__(self, current=None):
"""Iterates over all entries in this Attribute
Returns data from one entry at a time, starting at end and going
to beginning.
@note: Returned in entry-number order.
"""
if current is None:
current = self.max_idx()
while current >= 0:
if self.has_entry(current):
value = yield(self._get_entry(current))
if value != None:
current = value
current -= 1
def __len__(self):
"""Number of Entries for this Attr. NOT same as max Entry number.
@return: Number of Entries
@rtype: int
"""
count = ctypes.c_long(0)
self._call(const.GET_, self.ATTR_NUMENTRIES_, ctypes.byref(count))
return count.value
def __repr__(self):
"""Returns representation of an attribute
Cannot return anything that can be eval'd to create a copy of the
attribtute, so just wrap the informal representation in angle brackets.
@return: all the data in this attribute
@rtype: str
"""
return '<\n' + str(self) + '\n>'
def __str__(self):
"""Returns a string representation of the attribute
This is an 'informal' representation in that it cannot be evaluated
directly to create an L{Attr}.
@return: all the data in this attribute
@rtype: str
"""
if self._cdf_file._opened:
return '\n'.join([str(item) for item in self])
else:
if isinstance(self._name, str):
return 'Attribute "{0}" in closed CDF {1}'.format(
self._name, self._cdf_file.pathname)
else:
return 'Attribute "{0}" in closed CDF {1}'.format(
self._name.decode('ascii'),
self._cdf_file.pathname.decode('ascii'))
[docs] def insert(self, index, data):
"""Insert an entry at a particular number
Inserts entry at particular number while moving all subsequent
entries to one entry number later. Does not close gaps.
Parameters
==========
index : int
index where to put the new entry
data :
data for the new entry
"""
max_entry = self.max_idx()
if index > max_entry: #Easy case
self[index] = data
return
for i in range(max_entry, index - 1, -1):
if self.has_entry(i+1):
self.__delitem__(i+1)
if self.has_entry(i):
self.new(self.__getitem__(i), type=self.type(i), number=i+1)
self[index] = data
[docs] def append(self, data):
"""Add an entry to end of attribute
Puts entry after last defined entry (does not fill gaps)
Parameters
==========
data :
data for the new entry
"""
self[self.max_idx() + 1] = data
def _call(self, *args, **kwargs):
"""Select this CDF and Attr and call the CDF internal interface
@param args: Passed directly to the CDF library interface.
@type args: various, see `ctypes`.
@return: CDF status from the library
@rtype: ctypes.c_long
@note: Terminal NULL_ is automatically added to L{args}.
@raise CDFError: if CDF library reports an error
@raise CDFWarning: if CDF library reports a warning and interpreter
is set to error on warnings.
"""
return self._cdf_file._call(
const.SELECT_, const.ATTR_,
ctypes.c_long(self._cdf_file.attr_num(self._name)[0]),
*args, **kwargs)
def _entry_len(self, number):
"""Number of elements in an Entry
@param number: number of Entry
@type number: int
@return: number of elements
@rtype: int
"""
if not self.has_entry(number):
raise IndexError('list index ' + str(number) + ' out of range.')
count = ctypes.c_long(0)
self._call(
const.SELECT_, self.ENTRY_, ctypes.c_long(number),
const.GET_, self.ENTRY_NUMELEMS_, ctypes.byref(count))
return count.value
[docs] def type(self, number, new_type=None):
"""Find or change the CDF type of a particular Entry number
Parameters
==========
number : int
number of Entry to check or change
Other Parameters
================
new_type
type to change this Entry to, from `~spacepy.pycdf.const`.
Omit to only check type.
Returns
=======
out : int
CDF variable type, see `~spacepy.pycdf.const`
Notes
=====
If changing types, old and new must be equivalent, see CDF
User's Guide section 2.5.5 pg. 57
"""
if new_type != None:
if not hasattr(new_type, 'value'):
new_type = ctypes.c_long(new_type)
size = ctypes.c_long(self._entry_len(number))
status = self._call(const.SELECT_, self.ENTRY_, ctypes.c_long(number),
const.PUT_, self.ENTRY_DATASPEC_, new_type, size,
ignore=(const.NO_SUCH_ENTRY,))
if status == const.NO_SUCH_ENTRY:
raise IndexError('list index ' + str(number) + ' out of range.')
cdftype = ctypes.c_long(0)
status = self._call(const.SELECT_, self.ENTRY_, ctypes.c_long(number),
const.GET_, self.ENTRY_DATATYPE_, ctypes.byref(cdftype),
ignore=(const.NO_SUCH_ENTRY,))
if status == const.NO_SUCH_ENTRY:
raise IndexError('list index ' + str(number) + ' out of range.')
return cdftype.value
[docs] def has_entry(self, number):
"""Check if this attribute has a particular Entry number
Parameters
==========
number : int
number of Entry to check or change
Returns
=======
out : bool
True if ``number`` is a valid entry number; False if not
"""
status = self._call(const.CONFIRM_, self.ENTRY_EXISTENCE_,
ctypes.c_long(number),
ignore=(const.NO_SUCH_ENTRY, ))
return not status == const.NO_SUCH_ENTRY
[docs] def max_idx(self):
"""Maximum index of Entries for this Attr
Returns
=======
out : int
maximum Entry number
"""
count = ctypes.c_long(0)
self._call(const.GET_, self.ATTR_MAXENTRY_, ctypes.byref(count))
return count.value
[docs] def new(self, data, type=None, number=None):
"""Create a new Entry in this Attribute
.. note:: If ``number`` is provided and an Entry with that number
already exists, it will be overwritten.
Parameters
==========
data
data to put in the Entry
Other Parameters
================
type : int
type of the new Entry, from `~spacepy.pycdf.const`
(otherwise guessed from ``data``)
number : int
Entry number to write, default is lowest available number.
"""
if number is None:
number = 0
while self.has_entry(number):
number += 1
(dims, types, elements) = _Hyperslice.types(
data, backward=self._cdf_file.backward)
if type is None:
#Guess based on other entries
type = self._check_other_entries(types)
if type is None and self.ENTRY_ == const.zENTRY_:
#Try to match variable type
vartype = self._cdf_file[number].type()
if vartype in types:
type = vartype
if type is None:
type = types[0]
elif hasattr(type, 'value'):
type = type.value
self._write_entry(number, data, type, dims, elements)
[docs] def number(self):
"""Find the attribute number for this attribute
Returns
=======
out : int
attribute number
"""
no = ctypes.c_long(0)
self._cdf_file._call(const.GET_, const.ATTR_NUMBER_,
self._name, ctypes.byref(no))
return no.value
def global_scope(self):
"""Determine scope of this attribute.
Returns
=======
out : bool
True if global (i.e. gAttr), False if zAttr
"""
return self._cdf_file.attr_num(self._name)[1]
[docs] def rename(self, new_name):
"""Rename this attribute
Renaming a zAttribute renames it for *all* zVariables in this CDF!
Parameters
==========
new_name : str
the new name of the attribute
"""
try:
enc_name = new_name.encode('ascii')
except AttributeError:
enc_name = new_name
if len(enc_name) > const.CDF_ATTR_NAME_LEN256:
raise CDFError(const.BAD_ATTR_NAME)
self._call(const.PUT_, const.ATTR_NAME_, enc_name)
self._cdf_file.add_attr_to_cache(
enc_name,
*self._cdf_file.attr_num(self._name)) #still in cache
del self._cdf_file._attr_info[self._name]
self._name = enc_name
def _get_entry(self, number):
"""Read an Entry associated with this L{Attr}
@param number: number of Entry to return
@type number: int
@return: data from entry numbered L{number}
@rtype: list or str
"""
if not self.has_entry(number):
raise IndexError('list index ' + str(number) + ' out of range.')
#Make a big enough buffer
length = self._entry_len(number)
cdftype = self.type(number)
if cdftype in (const.CDF_CHAR.value, const.CDF_UCHAR.value):
buff = numpy.empty((), 'S{0}'.format(length), order='C')
else:
if not cdftype in lib.numpytypedict:
raise CDFError(const.BAD_DATA_TYPE)
buff = numpy.empty((length,), lib.numpytypedict[cdftype],
order='C')
buff = numpy.require(buff, requirements=('C', 'A', 'W'))
self._call(const.SELECT_, self.ENTRY_, ctypes.c_long(number),
const.GET_, self.ENTRY_DATA_,
buff.ctypes.data_as(ctypes.c_void_p))
#decode
if cdftype in (const.CDF_CHAR.value, const.CDF_UCHAR.value):
if self._raw:
result = bytes(buff)
else: # Make unicode
result = str(numpy.char.array(buff).decode(
encoding=self._cdf_file.encoding, errors='replace'))
else:
if not self._raw:
if cdftype == const.CDF_EPOCH.value:
result = lib.v_epoch_to_datetime(buff)
elif cdftype == const.CDF_EPOCH16.value:
result = lib.v_epoch16_to_datetime(buff)
elif cdftype == const.CDF_TIME_TT2000.value:
result = lib.v_tt2000_to_datetime(buff)
else:
result = buff
else:
result = buff
if length == 1:
result = result[0]
return result
def _write_entry(self, number, data, cdf_type, dims, elements):
"""Write an Entry to this Attr.
@param number: number of Entry to write
@type number: int
@param data: data to write
@param cdf_type: the CDF type to write, from `pycdf.const`
@param dims: dimensions of L{data}
@type dims: list
@param elements: number of elements in L{data}, 1 unless it is a string
@type elements: int
"""
n_write = 1 if len(dims) == 0 else dims[0]
if cdf_type in (const.CDF_CHAR.value, const.CDF_UCHAR.value):
if not self._raw:
data = numpy.asanyarray(data)
if data.dtype.kind == 'U':
data = numpy.char.encode(
data, encoding=self._cdf_file.encoding)
data = numpy.require(data, requirements=('C', 'A', 'W'),
dtype=numpy.dtype('S' + str(elements)))
n_write = elements
elif cdf_type == const.CDF_EPOCH16.value:
raw_in = True #Assume each element is pair of floats
if not self._raw:
try:
data = lib.v_datetime_to_epoch16(data)
raw_in = False #Nope, not raw, was datetime
except AttributeError:
pass
if raw_in: #Floats passed in, extra dim of (2,)
dims = dims[:-1]
if len(dims) == 0:
n_write = 1
data = numpy.require(data, requirements=('C', 'A', 'W'),
dtype=numpy.float64)
elif cdf_type == const.CDF_EPOCH.value:
if not self._raw:
try:
data = lib.v_datetime_to_epoch(data),
except AttributeError:
pass
data = numpy.require(data, requirements=('C', 'A', 'W'),
dtype=numpy.float64)
elif cdf_type == const.CDF_TIME_TT2000.value:
if not self._raw:
try:
data = lib.v_datetime_to_tt2000(data)
except AttributeError:
pass
data = numpy.require(data, requirements=('C', 'A', 'W'),
dtype=numpy.int64)
elif cdf_type in lib.numpytypedict:
data = numpy.require(data, requirements=('C', 'A', 'W'),
dtype=lib.numpytypedict[cdf_type])
else:
raise CDFError(const.BAD_DATA_TYPE)
self._call(const.SELECT_, self.ENTRY_, ctypes.c_long(number),
const.PUT_, self.ENTRY_DATA_, ctypes.c_long(cdf_type),
ctypes.c_long(n_write),
data.ctypes.data_as(ctypes.c_void_p))
def _delete(self):
"""Delete this Attribute
Also deletes all Entries associated with it.
"""
self._call(const.DELETE_, const.ATTR_)
self._cdf_file.clear_attr_from_cache(self._name)
self._name = None
[docs]class zAttr(Attr):
"""zAttribute for zVariables within a CDF.
.. warning::
Because zAttributes are shared across all variables in a CDF,
directly manipulating them may have unexpected consequences.
It is safest to operate on zEntries via `zAttrList`.
.. note::
When accessing a zAttr, pyCDF exposes only the zEntry corresponding
to the associated zVariable.
See Also
========
Attr
"""
ENTRY_ = const.zENTRY_
ENTRY_DATA_ = const.zENTRY_DATA_
SCOPE = const.VARIABLE_SCOPE
ENTRY_EXISTENCE_ = const.zENTRY_EXISTENCE_
ATTR_NUMENTRIES_ = const.ATTR_NUMzENTRIES_
ATTR_MAXENTRY_ = const.ATTR_MAXzENTRY_
ENTRY_NUMELEMS_ = const.zENTRY_NUMELEMS_
ENTRY_DATATYPE_ = const.zENTRY_DATATYPE_
ENTRY_DATASPEC_ = const.zENTRY_DATASPEC_
def insert(self, index, data):
"""Insert entry at particular index number
Since there can only be one zEntry per zAttr, this cannot be
implemented.
Raises
======
NotImplementedError : always
"""
raise NotImplementedError
def append(self, index, data):
"""Add entry to end of attribute list
Since there can only be one zEntry per zAttr, this cannot be
implemented.
Raises
======
NotImplementedError : always
"""
raise NotImplementedError
[docs]class gAttr(Attr):
"""Global Attribute for a CDF
Represents a CDF attribute, providing access to the gEntries in a format
that looks like a Python list. General list information is available in
the python docs:
`1 <http://docs.python.org/tutorial/introduction.html#lists>`_,
`2 <http://docs.python.org/tutorial/datastructures.html#more-on-lists>`_,
`3 <http://docs.python.org/library/stdtypes.html#typesseq>`_.
Normally accessed by providing a key to a `gAttrList`:
>>> attribute = cdffile.attrs['attribute_name']
>>> first_gentry = attribute[0]
Each element of the list is a single gEntry of the appropriate type.
The index to the elements is the gEntry number.
A gEntry may be either a single string or a 1D array of numerical type.
Entries of numerical type (everything but CDF_CHAR and CDF_UCHAR)
with a single element are returned as scalars; multiple-element entries
are returned as a list. No provision is made for accessing below
the entry level; the whole list is returned at once (but Python's
slicing syntax can be used to extract individual items from that list.)
Multi-dimensional slicing is *not* supported; an entry with multiple
elements will have all elements returned (and can thus be sliced itself).
Example:
>>> first_three = attribute[5, 0:3] #will fail
>>> first_three = attribute[5][0:3] #first three elements of 5th Entry
gEntries are *not* necessarily contiguous; a gAttribute may have an
entry 0 and entry 2 without an entry 1. :meth:`~Attr.len` will return the
*number* of gEntries; use :meth:`~Attr.max_idx` to find the highest defined
gEntry number and :meth:`~Attr.has_entry` to determine if a particular
gEntry number exists. Iterating over all entries is also supported::
>>> entrylist = [entry for entry in attribute]
Deleting gEntries will leave a "hole":
>>> attribute[0:3] = [1, 2, 3]
>>> del attribute[1]
>>> attribute.has_entry(1)
False
>>> attribute.has_entry(2)
True
>>> print attribute[0:3]
[1, None, 3]
Multi-element slices over nonexistent gEntries will return ``None`` where
no entry exists. Single-element indices for nonexistent gEntries will
raise ``IndexError``. Assigning ``None`` to a gEntry will delete it.
When assigning to a gEntry, the type is chosen to match the data;
subject to that constraint, it will try to match
(in order):
#. existing gEntry of the same number in this gAttribute
#. other gEntries in this gAttribute
#. data-matching constraints described in :meth:`CDF.new`.
See Also
========
Attr
"""
ENTRY_ = const.gENTRY_
ENTRY_DATA_ = const.gENTRY_DATA_
SCOPE = const.GLOBAL_SCOPE
ENTRY_EXISTENCE_ = const.gENTRY_EXISTENCE_
ATTR_NUMENTRIES_ = const.ATTR_NUMgENTRIES_
ATTR_MAXENTRY_ = const.ATTR_MAXgENTRY_
ENTRY_NUMELEMS_ = const.gENTRY_NUMELEMS_
ENTRY_DATATYPE_ = const.gENTRY_DATATYPE_
ENTRY_DATASPEC_ = const.gENTRY_DATASPEC_
[docs]class AttrList(MutableMapping):
"""Object representing a list of attributes.
.. warning::
This class should not be used directly, but only via its
subclasses, `gAttrList` and `zAttrList`.
Methods listed here are safe to use from the subclasses.
.. autosummary::
~AttrList.clone
~AttrList.copy
~AttrList.new
~AttrList.rename
.. automethod:: clone
.. automethod:: copy
.. automethod:: new
.. automethod:: rename
"""
def __init__(self, cdf_file, special_entry=None):
"""Initialize the attribute collection
@param cdf_file: CDF these attributes are in
@type cdf_file: `pycdf.CDF`
@param special_entry: callable which returns a "special" entry number,
used to limit results for zAttrs to those which match the zVar
(i.e. the var number)
@type special_entry: callable
"""
self._cdf_file = cdf_file
self.special_entry = special_entry
def __getitem__(self, name):
"""Find an Attribute by name
@param name: name of the Attribute to return
@type name: str
@return: attribute named L{name}
@rtype: L{Attr}
@raise KeyError: if there is no attribute named L{name}
@raise CDFError: other errors in CDF library
"""
try:
attrib = self.AttrType(self._cdf_file, name)
except CDFError:
(t, v, tb) = sys.exc_info()
if v.status == const.NO_SUCH_ATTR:
raise KeyError(name + ': ' + str(v))
else:
raise
if attrib.global_scope() != self.global_scope:
raise KeyError(name + ': no ' + self.attr_name + ' by that name.')
return attrib
def __setitem__(self, name, data):
"""Create an Attribute or change its entries
@param name: name of Attribute to change
@type name: str
@param data: Entries to populate this Attribute with.
Any existing Entries will be deleted!
Another C{Attr} may be specified, in which
case all its entries are copied.
@type data: scalar, list, or L{Attr}
"""
if isinstance(data, AttrList):
if name in self:
del self[name]
attr = self._get_or_create(name)
for entryno in range(data.max_idx()):
if data.has_entry(entryno):
attr.new(data[entryno], data.type(entryno), entryno)
else:
attr = self._get_or_create(name)
if isinstance(data, str_classes):
data = [data]
else:
try:
junk = len(data)
except TypeError:
data = [data]
attr[:] = data
del attr[len(data):]
def __delitem__(self, name):
"""Delete an Attribute (and all its entries)
@param name: name of Attribute to delete
@type name: str
"""
try:
attr = self.AttrType(self._cdf_file, name)
except CDFError:
(t, v, tb) = sys.exc_info()
if v.status == const.NO_SUCH_ATTR:
raise KeyError(name + ': ' + str(v))
else:
raise
if attr.global_scope() != self.global_scope:
raise KeyError(name + ': not ' + self.attr_name)
attr._delete()
def __iter__(self, current=0):
"""Iterates over all Attr in this CDF or variable
Returns name of one L{Attr} at a time until reaches the end.
@note: Returned in number order.
"""
count = ctypes.c_long(0)
self._cdf_file._call(const.GET_, const.CDF_NUMATTRS_,
ctypes.byref(count))
while current < count.value:
candidate = self.AttrType(self._cdf_file, current)
if candidate.global_scope() == self.global_scope:
if self.special_entry is None or \
candidate.has_entry(self.special_entry()):
value = yield(candidate._name.decode())
if value != None:
current = self[value].number()
current += 1
def __repr__(self):
"""Returns representation of attribute list
Cannot return anything that can be eval'd to create a copy of the
list, so just wrap the informal representation in angle brackets.
@return: all the data in this list of attributes
@rtype: str
"""
return '<' + self.__class__.__name__ + ':\n' + str(self) + '\n>'
def __str__(self):
"""Returns a string representation of the attribute list
This is an 'informal' representation in that it cannot be evaluated
directly to create an L{AttrList}.
@return: all the data in this list of attributes
@rtype: str
"""
if self._cdf_file._opened:
return '\n'.join([key + ': ' + (
('\n' + ' ' * (len(key) + 2)).join(
[str(value[i]) + ' [' + lib.cdftypenames[value.type(i)] + ']'
for i in range(value.max_idx() + 1) if value.has_entry(i)])
if isinstance(value, Attr)
else str(value) +
' [' + lib.cdftypenames[self.type(key)] + ']'
)
for (key, value) in sorted(self.items())])
else:
if isinstance(self._cdf_file.pathname, str):
return 'Attribute list in closed CDF {0}'.format(
self._cdf_file.pathname)
else:
return 'Attribute list in closed CDF {0}'.format(
self._cdf_file.pathname.decode('ascii'))
[docs] def clone(self, master, name=None, new_name=None):
"""
Clones another attribute list, or one attribute from it, into this
list.
Parameters
==========
master : AttrList
the attribute list to copy from. This can be any dict-like object.
Other Parameters
================
name : str (optional)
name of attribute to clone (default: clone entire list)
new_name : str (optional)
name of the new attribute, default ``name``
"""
if name is None:
self._clone_list(master)
else:
self._clone_attr(master, name, new_name)
[docs] def copy(self):
"""
Create a copy of this attribute list
Returns
=======
out : dict
copy of the entries for all attributes in this list
"""
return dict((key, value[:] if isinstance(value, Attr) else value)
for (key, value) in self.items())
[docs] def new(self, name, data=None, type=None):
"""
Create a new Attr in this AttrList
Parameters
==========
name : str
name of the new Attribute
Other Parameters
================
data
data to put into the first entry in the new Attribute
type
CDF type of the first entry from `~spacepy.pycdf.const`.
Only used if data are specified.
Raises
======
KeyError : if the name already exists in this list
"""
if name in self:
raise KeyError(name + ' already exists.')
#A zAttr without an Entry in this zVar will be a "get" not "create"
attr = self._get_or_create(name)
if data is not None:
if self.special_entry is None:
attr.new(data, type)
else:
attr.new(data, type, self.special_entry())
[docs] def rename(self, old_name, new_name):
"""
Rename an attribute in this list
Renaming a zAttribute renames it for *all* zVariables in this CDF!
Parameters
==========
old_name : str
the current name of the attribute
new_name : str
the new name of the attribute
"""
AttrList.__getitem__(self, old_name).rename(new_name)
def _clone_attr(self, master, name, new_name=None):
"""Clones a single attribute from one in this list or another
Copies data and types from the master attribute to the new one
@param master: attribute list to copy attribute from
@type master: L{AttrList}
@param name: name of attribute to copy
@type name: str
@param new_name: name of the new attribute, default L{name}
@type new_name: str
"""
if new_name is None:
new_name = name
self[new_name] = master[name]
def _clone_list(self, master):
"""Clones this attribute list from another
@param master: the attribute list to copy from
@type master: L{AttrList}
"""
for name in master:
self._clone_attr(master, name)
for name in list(self): #Can't iterate over a list we're changing
if not name in master:
del self[name]
def _get_or_create(self, name):
"""Retrieve L{Attr} or create it if it doesn't exist
@param name: name of the attribute to look up or create
@type name: str
@return: attribute with this name
@rtype: L{Attr}
"""
attr = None
try:
attr = self.AttrType(self._cdf_file, name)
except CDFError:
(t, v, tb) = sys.exc_info()
if v.status != const.NO_SUCH_ATTR:
raise
if attr is None:
attr = self.AttrType(self._cdf_file, name, True)
elif attr.global_scope() != self.global_scope:
raise KeyError(name + ': not ' + self.attr_name)
return attr
[docs]class gAttrList(AttrList):
"""
Object representing *all* the gAttributes in a CDF.
Normally accessed as an attribute of an open `CDF`:
>>> global_attribs = cdffile.attrs
Appears as a dictionary: keys are attribute names; each value is an
attribute represented by a `gAttr` object. To access the global
attribute TEXT:
>>> text_attr = cdffile.attrs['TEXT']
See Also
========
AttrList
"""
AttrType = gAttr
attr_name = 'gAttribute'
global_scope = True
def __len__(self):
"""
Number of gAttributes in this CDF
Returns
=======
out : int
number of gAttributes in the CDF
"""
count = ctypes.c_long(0)
self._cdf_file._call(const.GET_, const.CDF_NUMgATTRS_,
ctypes.byref(count))
return count.value
[docs]class zAttrList(AttrList):
"""Object representing *all* the zAttributes in a zVariable.
Normally accessed as an attribute of a `Var` in an open
CDF:
>>> epoch_attribs = cdffile['Epoch'].attrs
Appears as a dictionary: keys are attribute names, values are
the value of the zEntry associated with the appropriate zVariable.
Each vAttribute in a CDF may only have a *single* entry associated
with each variable. The entry may be a string, a single numerical value,
or a series of numerical values. Entries with multiple values are returned
as an entire list; direct access to the individual elements is not
possible.
Example: finding the first dependency of (ISTP-compliant) variable
``Flux``:
>>> print cdffile['Flux'].attrs['DEPEND_0']
zAttributes are shared among zVariables, one zEntry allowed per zVariable.
(pyCDF hides this detail.) Deleting the last zEntry for a zAttribute will
delete the underlying zAttribute.
zEntries are created and destroyed by the usual dict methods on the
zAttrlist:
>>> epoch_attribs['new_entry'] = [1, 2, 4] #assign a list to new zEntry
>>> del epoch_attribs['new_entry'] #delete the zEntry
The type of the zEntry is guessed from data provided. The type is chosen to
match the data; subject to that constraint, it will try to match
(in order):
#. existing zEntry corresponding to this zVar
#. other zEntries in this zAttribute
#. the type of this zVar
#. data-matching constraints described in :meth:`CDF.new`
See Also
========
AttrList
"""
AttrType = zAttr
attr_name = 'zAttribute'
global_scope = False
def __init__(self, zvar):
"""Initialize the attribute collection
@param zvar: zVariable these attributes are in
@param zvar: `pycdf.Var`
"""
super(zAttrList, self).__init__(zvar.cdf_file, zvar._num)
self._zvar = zvar
def __getitem__(self, name):
"""Find an zEntry by name
@param name: name of the zAttribute to return
@type name: str
@return: attribute named L{name}
@rtype: L{zAttr}
@raise KeyError: if there is no attribute named L{name} associated
with this zVariable
@raise CDFError: other errors in CDF library
"""
attrib = super(zAttrList, self).__getitem__(name)
zvar_num = self._zvar._num()
if attrib.has_entry(zvar_num):
attrib._raw = self._zvar._raw
return attrib[zvar_num]
else:
raise KeyError(name + ': no such attribute for variable ' +
self._zvar.name())
def __delitem__(self, name):
"""Delete an zEntry by name
@param name: name of the zEntry to delete
@type name: str
@raise KeyError: if there is no attribute named L{name} associated
with this zVariable
@raise CDFError: other errors in CDF library
@note: If this is the only remaining entry, the Attribute will be
deleted.
"""
attrib = super(zAttrList, self).__getitem__(name)
zvar_num = self._zvar._num()
if not attrib.has_entry(zvar_num):
raise KeyError(str(name) + ': no such attribute for variable ' +
str(self._zvar._name))
del attrib[zvar_num]
if len(attrib) == 0:
attrib._delete()
def __setitem__(self, name, data):
"""Sets a zEntry by name
The type of the zEntry is guessed from L{data}. The type is chosen to
match the data; subject to that constraint, it will try to match
(in order):
1. existing zEntry corresponding to this zVar
2. other zEntries in this zAttribute
3. the type of this zVar
4. data-matching constraints described in L{_Hyperslice.types}
@param name: name of zAttribute; zEntry for this zVariable will be set
in zAttribute by this name
@type name: str
@raise CDFError: errors in CDF library
@raise ValueError: if unable to find a valid CDF type matching L{data},
or if L{data} is the wrong dimensions.
"""
try:
attr = super(zAttrList, self).__getitem__(name)
except KeyError:
attr = zAttr(self._cdf_file, name, True)
attr._raw = self._zvar._raw
attr[self._zvar._num()] = data
def __len__(self):
"""Number of zAttributes in this variable
@return: number of zAttributes in the CDF
which have entries for this variable.
@rtype: int
"""
length = 0
count = ctypes.c_long(0)
self._cdf_file._call(const.GET_, const.CDF_NUMATTRS_,
ctypes.byref(count))
current = 0
while current < count.value:
candidate = zAttr(self._cdf_file, current)
if not candidate.global_scope():
if candidate.has_entry(self._zvar._num()):
length += 1
current += 1
return length
def type(self, name, new_type=None):
"""Find or change the CDF type of a zEntry in this zVar
@param name: name of the zAttr to check or change
@type name: str
@param new_type: type to change it to, see `pycdf.const`
@type new_type: ctypes.c_long
@return: CDF variable type, see `pycdf.const`
@rtype: int
@note: If changing types, old and new must be equivalent, see CDF
User's Guide section 2.5.5 pg. 57
"""
attrib = super(zAttrList, self).__getitem__(name)
zvar_num = self._zvar._num()
if not attrib.has_entry(zvar_num):
raise KeyError(name + ': no such attribute for variable ' +
self._zvar.name())
return attrib.type(zvar_num, new_type)
def _clone_attr(self, master, name, new_name=None):
"""Clones a single attribute from one in this list or another
Copies data and types from the master attribute to the new one
@param master: attribute list to copy attribute from
@type master: L{zAttrList}
@param name: name of attribute to copy
@type name: str
@param new_name: name of the new attribute, default L{name}
@type new_name: str
"""
if new_name is None:
new_name = name
if new_name in self:
del self[new_name]
self.new(new_name, master[name],
master.type(name) if hasattr(master, 'type') else None)
