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# The read and write methods for SpectralCube, StokesSpectralCube, and
# LowerDimensionalObject are defined in this file and then added to the classes
# using UnifiedReadWriteMethod. This makes it possible to dynamically add the
# available formats to the read/write docstrings. For more information about
# the unified I/O framework from Astropy which is used to implement this, see
# http://docs.astropy.org/en/stable/io/unified.html
from pathlib import PosixPath
import warnings
from astropy.io import registry
from ..utils import StokesWarning
__doctest_skip__ = ['SpectralCubeRead',
'SpectralCubeWrite',
'StokesSpectralCubeRead',
'StokesSpectralCubeWrite',
'LowerDimensionalObjectWrite']
DOCSTRING_READ_TEMPLATE = """
Read and parse a dataset and return as a {clsname}
This allows easily reading a dataset in several supported data
formats using syntax such as::
>>> from spectral_cube import {clsname}
>>> cube1 = {clsname}.read('cube.fits', format='fits')
>>> cube2 = {clsname}.read('cube.image', format='casa')
{notes}
Get help on the available readers for {clsname} using the``help()`` method::
>>> {clsname}.read.help() # Get help reading {clsname} and list supported formats
>>> {clsname}.read.help('fits') # Get detailed help on {clsname} FITS reader
>>> {clsname}.read.list_formats() # Print list of available formats
See also: http://docs.astropy.org/en/stable/io/unified.html
Parameters
----------
*args : tuple, optional
Positional arguments passed through to data reader. If supplied the
first argument is typically the input filename.
format : str
File format specifier.
**kwargs : dict, optional
Keyword arguments passed through to data reader.
Returns
-------
cube : `{clsname}`
{clsname} corresponding to dataset
Notes
-----
"""
DOCSTRING_WRITE_TEMPLATE = """
Write this {clsname} object out in the specified format.
This allows easily writing a dataset in many supported data formats
using syntax such as::
>>> data.write('data.fits', format='fits')
Get help on the available writers for {clsname} using the``help()`` method::
>>> {clsname}.write.help() # Get help writing {clsname} and list supported formats
>>> {clsname}.write.help('fits') # Get detailed help on {clsname} FITS writer
>>> {clsname}.write.list_formats() # Print list of available formats
See also: http://docs.astropy.org/en/stable/io/unified.html
Parameters
----------
*args : tuple, optional
Positional arguments passed through to data writer. If supplied the
first argument is the output filename.
format : str
File format specifier.
**kwargs : dict, optional
Keyword arguments passed through to data writer.
Notes
-----
"""
# Due to a bug in the astropy I/O infrastructure which causes an exception
# for directories (which we need for .image), we need to wrap the filenames in
# a custom string so that astropy doesn't try and call get_readable_fileobj on
# them.
class StringWrapper:
def __init__(self, value):
self.value = value
class SpectralCubeRead(registry.UnifiedReadWrite):
__doc__ = DOCSTRING_READ_TEMPLATE.format(clsname='SpectralCube',
notes="If the file contains Stokes axes, they will automatically be dropped. If "
"you want to read in all Stokes informtion, use "
":meth:`~spectral_cube.StokesSpectralCube.read` instead.")
def __init__(self, instance, cls):
super().__init__(instance, cls, 'read')
def __call__(self, filename, *args, **kwargs):
from ..spectral_cube import BaseSpectralCube
if isinstance(filename, PosixPath):
filename = str(filename)
kwargs['target_cls'] = BaseSpectralCube
try:
return registry.read(BaseSpectralCube, filename, *args, **kwargs)
except IsADirectoryError: # See note above StringWrapper
return registry.read(BaseSpectralCube, StringWrapper(filename), *args, **kwargs)
class SpectralCubeWrite(registry.UnifiedReadWrite):
__doc__ = DOCSTRING_WRITE_TEMPLATE.format(clsname='SpectralCube')
def __init__(self, instance, cls):
super().__init__(instance, cls, 'write')
def __call__(self, *args, serialize_method=None, **kwargs):
registry.write(self._instance, *args, **kwargs)
class StokesSpectralCubeRead(registry.UnifiedReadWrite):
__doc__ = DOCSTRING_READ_TEMPLATE.format(clsname='StokesSpectralCube',
notes="If the file contains Stokes axes, they will be read in. If you are only "
"interested in the unpolarized emission (I), you can use "
":meth:`~spectral_cube.SpectralCube.read` instead.")
def __init__(self, instance, cls):
super().__init__(instance, cls, 'read')
def __call__(self, filename, *args, **kwargs):
from ..stokes_spectral_cube import StokesSpectralCube
if isinstance(filename, PosixPath):
filename = str(filename)
kwargs['target_cls'] = StokesSpectralCube
try:
return registry.read(StokesSpectralCube, filename, *args, **kwargs)
except IsADirectoryError: # See note above StringWrapper
return registry.read(StokesSpectralCube, StringWrapper(filename), *args, **kwargs)
class StokesSpectralCubeWrite(registry.UnifiedReadWrite):
__doc__ = DOCSTRING_WRITE_TEMPLATE.format(clsname='StokesSpectralCube')
def __init__(self, instance, cls):
super().__init__(instance, cls, 'write')
def __call__(self, *args, serialize_method=None, **kwargs):
registry.write(self._instance, *args, **kwargs)
class LowerDimensionalObjectWrite(registry.UnifiedReadWrite):
__doc__ = DOCSTRING_WRITE_TEMPLATE.format(clsname='LowerDimensionalObject')
def __init__(self, instance, cls):
super().__init__(instance, cls, 'write')
def __call__(self, *args, serialize_method=None, **kwargs):
registry.write(self._instance, *args, **kwargs)
def normalize_cube_stokes(cube, target_cls=None):
from ..spectral_cube import BaseSpectralCube
from ..stokes_spectral_cube import StokesSpectralCube
if target_cls is BaseSpectralCube and isinstance(cube, StokesSpectralCube):
if hasattr(cube, 'I'):
warnings.warn("Cube is a Stokes cube, "
"returning spectral cube for I component",
StokesWarning)
return cube.I
else:
raise ValueError("Spectral cube is a Stokes cube that "
"does not have an I component")
elif target_cls is StokesSpectralCube and isinstance(cube, BaseSpectralCube):
return StokesSpectralCube({'I': cube})
else:
return cube
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