lsst.afw  21.0.0-21-g5d80ea29e+e0d7160dc8
_pickleFits.py
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21 
22 from lsst.afw.fits import MemFileManager, ImageWriteOptions, ImageCompressionOptions
23 
24 import lsst.afw.table
25 import lsst.afw.image
26 
27 
28 def reduceToFits(obj):
29  """Pickle to FITS
30 
31  Intended to be used by the ``__reduce__`` method of a class.
32 
33  Parameters
34  ----------
35  obj
36  any object with a ``writeFits`` method taking a
37  `~lsst.afw.fits.MemFileManager` and possibly an
38  `~lsst.afw.fits.ImageWriteOptions`.
39 
40  Returns
41  -------
42  reduced : `tuple` [callable, `tuple`]
43  a tuple in the format returned by `~object.__reduce__`
44  """
45  manager = MemFileManager()
46  options = ImageWriteOptions(ImageCompressionOptions(ImageCompressionOptions.NONE))
47  table = getattr(obj, 'table', None)
48  if isinstance(table, lsst.afw.table.BaseTable):
49  # table objects don't take `options`
50  obj.writeFits(manager)
51  else:
52  # MaskedImage and Exposure both require options for each plane (image, mask, variance)
54  obj.writeFits(manager, options, options, options)
55  else:
56  obj.writeFits(manager, options)
57  size = manager.getLength()
58  data = manager.getData()
59  return (unreduceFromFits, (obj.__class__, data, size))
60 
61 
62 def unreduceFromFits(cls, data, size):
63  """Unpickle from FITS
64 
65  Unpack data produced by `reduceToFits`. This method is used by the
66  pickling framework and should not need to be called from user code.
67 
68  Parameters
69  ----------
70  cls : `type`
71  the class of object to unpickle. Must have a class-level ``readFits``
72  method taking a `~lsst.afw.fits.MemFileManager`.
73  data : `bytes`
74  an in-memory representation of the object, compatible with
75  `~lsst.afw.fits.MemFileManager`
76  size : `int`
77  the length of `data`
78 
79  Returns
80  -------
81  unpickled : ``cls``
82  the object represented by ``data``
83  """
84  manager = MemFileManager(size)
85  manager.setData(data, size)
86  return cls.readFits(manager)
Lifetime-management for memory that goes into FITS memory files.
Definition: fits.h:121
A class to contain the data, WCS, and other information needed to describe an image of the sky.
Definition: Exposure.h:72
A class to manipulate images, masks, and variance as a single object.
Definition: MaskedImage.h:73
Base class for all tables.
Definition: BaseTable.h:61
def unreduceFromFits(cls, data, size)
Definition: _pickleFits.py:62
Backwards-compatibility support for depersisting the old Calib (FluxMag0/FluxMag0Err) objects.
Options for tile compression of image pixels.
Options for writing an image to FITS.
Definition: fits.h:219