def test_header_read_restore(self):
# Test that reading a header restores the file position
trk_fname = DATA['simple_trk_fname']
bio = BytesIO()
bio.write(b'Along my very merry way')
hdr_pos = bio.tell()
hdr_from_fname = TrkFile._read_header(trk_fname)
with open(trk_fname, 'rb') as fobj:
bio.write(fobj.read())
bio.seek(hdr_pos)
# Check header is as expected
hdr_from_fname['_offset_data'] += hdr_pos # Correct for start position
assert_arr_dict_equal(TrkFile._read_header(bio), hdr_from_fname)
# Check fileobject file position has not changed
assert_equal(bio.tell(), hdr_pos)
def test_load_write_LPS_file(self):
# Load the RAS and LPS version of the standard.
trk_RAS = TrkFile.load(DATA['standard_trk_fname'], lazy_load=False)
trk_LPS = TrkFile.load(DATA['standard_LPS_trk_fname'], lazy_load=False)
assert_tractogram_equal(trk_LPS.tractogram, trk_RAS.tractogram)
# Write back the standard.
trk_file = BytesIO()
trk = TrkFile(trk_LPS.tractogram, trk_LPS.header)
trk.save(trk_file)
trk_file.seek(0, os.SEEK_SET)
new_trk = TrkFile.load(trk_file)
assert_arr_dict_equal(new_trk.header, trk.header)
assert_tractogram_equal(new_trk.tractogram, trk.tractogram)
new_trk_orig = TrkFile.load(DATA['standard_LPS_trk_fname'])
assert_tractogram_equal(new_trk.tractogram, new_trk_orig.tractogram)
trk_file.seek(0, os.SEEK_SET)
assert_equal(trk_file.read(),
open(DATA['standard_LPS_trk_fname'], 'rb').read())
# Test writing a file where the header is missing the
# Field.VOXEL_ORDER.
trk_file = BytesIO()
# For TRK file format, the default voxel order is LPS.
header = copy.deepcopy(trk_LPS.header)
header[Field.VOXEL_ORDER] = b""
trk = TrkFile(trk_LPS.tractogram, header)
trk.save(trk_file)
trk_file.seek(0, os.SEEK_SET)
new_trk = TrkFile.load(trk_file)
assert_arr_dict_equal(new_trk.header, trk_LPS.header)
assert_tractogram_equal(new_trk.tractogram, trk.tractogram)
new_trk_orig = TrkFile.load(DATA['standard_LPS_trk_fname'])
assert_tractogram_equal(new_trk.tractogram, new_trk_orig.tractogram)
trk_file.seek(0, os.SEEK_SET)
assert_equal(trk_file.read(),
open(DATA['standard_LPS_trk_fname'], 'rb').read())