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# Pure Python + Numpy implementation of CASA's getdminfo() function | ||
# for reading metadata about .image files | ||
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import os | ||
import sys | ||
import struct | ||
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import numpy as np | ||
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def read_int(f): | ||
return np.int32(struct.unpack('>I', f.read(4))[0]) | ||
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def read_string(f): | ||
value = read_int(f) | ||
return f.read(int(value)) | ||
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def read_vector(f): | ||
nelem = read_int(f) | ||
return np.array([read_int(f) for i in range(nelem)]) | ||
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def with_nbytes_prefix(func): | ||
def wrapper(f): | ||
start = f.tell() | ||
nbytes = read_int(f) | ||
result = func(f) | ||
end = f.tell() | ||
if end - start != nbytes: | ||
raise IOError('Function {0} read {1} bytes instead of {2}' | ||
.format(func, end - start, nbytes)) | ||
return result | ||
return wrapper | ||
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@with_nbytes_prefix | ||
def _read_iposition(f): | ||
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title = read_string(f) | ||
assert title == b'IPosition' | ||
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# Not sure what the next value is, seems to always be one. | ||
# Maybe number of dimensions? | ||
number = read_int(f) | ||
assert number == 1 | ||
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return read_vector(f) | ||
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def read_type(f): | ||
tp = read_string(f) | ||
version = read_int(f) | ||
return tp, version | ||
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@with_nbytes_prefix | ||
def read_record(f): | ||
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stype, sversion = read_type(f) | ||
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if stype != b'Record' or sversion != 1: | ||
raise NotImplementedError('Support for {0} version {1} not implemented'.format(stype, sversion)) | ||
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read_record_desc(f) | ||
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# Not sure what the following value is | ||
read_int(f) | ||
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@with_nbytes_prefix | ||
def read_record_desc(f): | ||
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stype, sversion = read_type(f) | ||
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if stype != b'RecordDesc' or sversion != 2: | ||
raise NotImplementedError('Support for {0} version {1} not implemented'.format(stype, sversion)) | ||
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# Not sure what the following value is | ||
read_int(f) | ||
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@with_nbytes_prefix | ||
def read_tiled_st_man(f): | ||
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# The code in this function corresponds to TiledStMan::headerFileGet | ||
# https://github.com/casacore/casacore/blob/75b358be47039250e03e5042210cbc60beaaf6e4/tables/DataMan/TiledStMan.cc#L1086 | ||
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stype, sversion = read_type(f) | ||
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if stype != b'TiledStMan' or sversion != 2: | ||
raise NotImplementedError('Support for {0} version {1} not implemented'.format(stype, sversion)) | ||
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st_man = {} | ||
st_man['SPEC'] = {} | ||
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big_endian = f.read(1) # noqa | ||
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seqnr = read_int(f) | ||
if seqnr != 0: | ||
raise ValueError("Expected seqnr to be 0, got {0}".format(seqnr)) | ||
st_man['SEQNR'] = seqnr | ||
st_man['SPEC']['SEQNR'] = seqnr | ||
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nrows = read_int(f) | ||
if nrows != 1: | ||
raise ValueError("Expected nrows to be 1, got {0}".format(nrows)) | ||
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ncols = read_int(f) | ||
if ncols != 1: | ||
raise ValueError("Expected ncols to be 1, got {0}".format(ncols)) | ||
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dtype = read_int(f) # noqa | ||
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column_name = read_string(f).decode('ascii') | ||
st_man['COLUMNS'] = np.array([column_name], dtype='<U16') | ||
st_man['NAME'] = column_name | ||
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max_cache_size = read_int(f) | ||
st_man['SPEC']['MAXIMUMCACHESIZE'] = max_cache_size | ||
st_man['SPEC']['MaxCacheSize'] = max_cache_size | ||
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ndim = read_int(f) | ||
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nrfile = read_int(f) # 1 | ||
if nrfile != 1: | ||
raise ValueError("Expected nrfile to be 1, got {0}".format(nrfile)) | ||
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# The following flag seems to control whether or not the TSM file is | ||
# opened by CASA, and is probably safe to ignore here. | ||
flag = bool(f.read(1)) | ||
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# The following two values are unknown, but are likely relevant when there | ||
# are more that one field in the image. | ||
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unknown = read_int(f) # 0 | ||
unknown = read_int(f) # 0 | ||
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bucket = st_man['SPEC']['HYPERCUBES'] = {} | ||
bucket = st_man['SPEC']['HYPERCUBES']['*1'] = {} | ||
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total_cube_size = read_int(f) # noqa | ||
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unknown = read_int(f) # 1 | ||
unknown = read_int(f) # 1 | ||
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read_record(f) | ||
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flag = f.read(1) # noqa | ||
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ndim = read_int(f) # noqa | ||
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bucket['CubeShape'] = bucket['CellShape'] = _read_iposition(f) | ||
bucket['TileShape'] = _read_iposition(f) | ||
bucket['ID'] = {} | ||
bucket['BucketSize'] = int(total_cube_size / np.product(np.ceil(bucket['CubeShape'] / bucket['TileShape']))) | ||
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unknown = read_int(f) # noqa | ||
unknown = read_int(f) # noqa | ||
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st_man['TYPE'] = 'TiledCellStMan' | ||
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return st_man | ||
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@with_nbytes_prefix | ||
def read_tiled_cell_st_man(f): | ||
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stype, sversion = read_type(f) | ||
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if stype != b'TiledCellStMan' or sversion != 1: | ||
raise NotImplementedError('Support for {0} version {1} not implemented'.format(stype, sversion)) | ||
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default_tile_shape = _read_iposition(f) | ||
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st_man = read_tiled_st_man(f) | ||
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st_man['SPEC']['DEFAULTTILESHAPE'] = default_tile_shape | ||
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return {'*1': st_man} | ||
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def getdminfo(filename): | ||
""" | ||
Return the same output as CASA's getdminfo() function, namely a dictionary | ||
with metadata about the .image file, parsed from the ``table.f0`` file. | ||
""" | ||
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with open(os.path.join(filename, 'table.f0'), 'rb') as f: | ||
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magic = f.read(4) | ||
if magic != b'\xbe\xbe\xbe\xbe': | ||
raise ValueError('Incorrect magic code: {0}'.format(magic)) | ||
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return read_tiled_cell_st_man(f) |
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Original file line number | Diff line number | Diff line change |
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from __future__ import print_function, absolute_import, division | ||
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import pytest | ||
import numpy as np | ||
from pprint import pformat | ||
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from ..casa_dminfo import getdminfo | ||
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try: | ||
from casatools import table, image | ||
CASATOOLS_INSTALLED = True | ||
except ImportError: | ||
CASATOOLS_INSTALLED = False | ||
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SHAPES = [(3,), (5, 3), (8, 4, 2), (4, 8, 3, 1), (133, 400), (100, 211, 201), | ||
(50, 61, 72, 83), (4, 8, 10, 20, 40)] | ||
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@pytest.mark.skipif('not CASATOOLS_INSTALLED') | ||
@pytest.mark.parametrize('shape', SHAPES) | ||
def test_getdminfo(tmp_path, shape): | ||
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filename = str(tmp_path / 'test.image') | ||
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data = np.random.random(shape) | ||
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ia = image() | ||
ia.fromarray(outfile=filename, pixels=data) | ||
ia.close() | ||
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tb = table() | ||
tb.open(filename) | ||
reference = tb.getdminfo() | ||
tb.close() | ||
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actual = getdminfo(filename) | ||
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# The easiest way to compare the output is simply to compare the output | ||
# from pformat (checking for dictionary equality doesn't work because of | ||
# the Numpy arrays inside). | ||
assert pformat(actual) == pformat(reference) |