lsst.pipe.drivers.checksum Namespace Reference

Functions
def	checksum (obj, header=None, sumType="MD5")
	Calculate a checksum of an object. More...

Variables
tuple	exposureTypes = (afwImage.ExposureF, afwImage.ExposureD,)
tuple	maskedImageTypes = (afwImage.MaskedImageF, afwImage.MaskedImageD,)
tuple	decoratedImageTypes = (afwImage.DecoratedImageF, afwImage.DecoratedImageD,)
tuple	imageTypes = (afwImage.ImageF, afwImage.ImageD, afwImage.ImageI,)
int	PROTOCOL = 2
dictionary	sumFunctions

Function Documentation

checksum()

def lsst.pipe.drivers.checksum.checksum	(		obj,
			header = None,
			sumType = "MD5"
	)

Calculate a checksum of an object.

We have special handling for images (e.g., breaking a MaskedImage into
its various components), but the object may be any picklable type.

@param obj  Object for which to calculate the checksum
@param header  FITS header (PropertyList) to update with checksum values, or None
@param sumType  Type of checksum to calculate
@return dict with header keyword,value pairs

Definition at line 24 of file checksum.py.

def checksum(obj, header=None, sumType="MD5"):
    """!Calculate a checksum of an object
 
    We have special handling for images (e.g., breaking a MaskedImage into
    its various components), but the object may be any picklable type.
 
    @param obj  Object for which to calculate the checksum
    @param header  FITS header (PropertyList) to update with checksum values, or None
    @param sumType  Type of checksum to calculate
    @return dict with header keyword,value pairs
    """
    assert sumType in sumFunctions, "Unknown sumType: %s" % (sumType,)
    func = sumFunctions[sumType]
 
    results = {}
 
    if isinstance(obj, exposureTypes):
        obj = obj.getMaskedImage()
    if isinstance(obj, decoratedImageTypes):
        obj = obj.getImage()
 
    if isinstance(obj, maskedImageTypes):
        results[sumType + "_IMAGE"] = func(obj.getImage())
        results[sumType + "_MASK"] = func(obj.getMask())
        results[sumType + "_VARIANCE"] = func(obj.getVariance())
    elif isinstance(obj, imageTypes):
        results[sumType + "_IMAGE"] = func(obj)
    else:
        results[sumType] = func(obj)
 
    if header is not None:
        for k, v in results.items():
            header.add(k, v)
 
    return results

Variable Documentation

decoratedImageTypes

tuple lsst.pipe.drivers.checksum.decoratedImageTypes = (afwImage.DecoratedImageF, afwImage.DecoratedImageD,)

Definition at line 12 of file checksum.py.

exposureTypes

tuple lsst.pipe.drivers.checksum.exposureTypes = (afwImage.ExposureF, afwImage.ExposureD,)

Definition at line 10 of file checksum.py.

imageTypes

tuple lsst.pipe.drivers.checksum.imageTypes = (afwImage.ImageF, afwImage.ImageD, afwImage.ImageI,)

Definition at line 13 of file checksum.py.

maskedImageTypes

tuple lsst.pipe.drivers.checksum.maskedImageTypes = (afwImage.MaskedImageF, afwImage.MaskedImageD,)

Definition at line 11 of file checksum.py.

PROTOCOL

int lsst.pipe.drivers.checksum.PROTOCOL = 2

Definition at line 15 of file checksum.py.

sumFunctions

dictionary lsst.pipe.drivers.checksum.sumFunctions

Initial value:

=  {
    "CRC32": lambda obj: zlib.crc32(pickle.dumps(obj, PROTOCOL)),
    "MD5": lambda obj: hashlib.md5(pickle.dumps(obj, PROTOCOL)).hexdigest(),
}

Definition at line 18 of file checksum.py.