def test_pixel_to_pixel_correlation_matrix_nonsquare():
# Here we set up an input WCS that maps 3 pixel coordinates to 4 world
# coordinates - the idea is to make sure that things work fine in cases
# where the number of input and output pixel coordinates do not match.
class FakeWCS(object):
pass
wcs_in = FakeWCS()
wcs_in.low_level_wcs = wcs_in
wcs_in.pixel_n_dim = 3
wcs_in.world_n_dim = 4
wcs_in.axis_correlation_matrix = [[True, True, False], [True, True, False],
[True, True, False],
[False, False, True]]
wcs_in.world_axis_object_components = [('spat', 'ra', 'ra.degree'),
('spat', 'dec', 'dec.degree'),
('spec', 0, 'value'),
('time', 0, 'utc.value')]
wcs_in.world_axis_object_classes = {
'spat': ('astropy.coordinates.SkyCoord', (), {
'frame': 'icrs'
}),
'spec': ('astropy.units.Wavelength', (None, ), {}),
'time': ('astropy.time.Time', (None, ), {
'format': 'mjd',
'scale': 'utc'
})
}
wcs_out = FakeWCS()
wcs_out.low_level_wcs = wcs_out
wcs_out.pixel_n_dim = 4
wcs_out.world_n_dim = 4
wcs_out.axis_correlation_matrix = [[True, False, False, False],
[False, True, True, False],
[False, True, True, False],
[False, False, False, True]]
wcs_out.world_axis_object_components = [('spec', 0, 'value'),
('spat', 'ra', 'ra.degree'),
('spat', 'dec', 'dec.degree'),
('time', 0, 'utc.value')]
wcs_out.world_axis_object_classes = wcs_in.world_axis_object_classes
matrix = _pixel_to_pixel_correlation_matrix(wcs_in, wcs_out)
matrix = matrix.astype(int)
# The shape should be (n_pixel_out, n_pixel_in)
assert matrix.shape == (4, 3)
expected = np.array([[1, 1, 0], [1, 1, 0], [1, 1, 0], [0, 0, 1]])
assert_equal(matrix, expected)
def test_pixel_to_pixel_correlation_matrix_celestial():
wcs_in = WCS(naxis=2)
wcs_in.wcs.ctype = 'RA---TAN', 'DEC--TAN'
wcs_in.wcs.set()
wcs_out = WCS(naxis=2)
wcs_out.wcs.ctype = 'DEC--TAN', 'RA---TAN'
wcs_out.wcs.set()
matrix = _pixel_to_pixel_correlation_matrix(wcs_in, wcs_out)
assert_equal(matrix, [[1, 1], [1, 1]])
def test_pixel_to_pixel_correlation_matrix_spectral_cube_uncorrelated():
wcs_in = WCS(naxis=3)
wcs_in.wcs.ctype = 'RA---TAN', 'DEC--TAN', 'FREQ'
wcs_in.wcs.set()
wcs_out = WCS(naxis=3)
wcs_out.wcs.ctype = 'DEC--TAN', 'FREQ', 'RA---TAN'
wcs_out.wcs.set()
matrix = _pixel_to_pixel_correlation_matrix(wcs_in, wcs_out)
assert_equal(matrix, [[1, 1, 0], [0, 0, 1], [1, 1, 0]])
def test_pixel_to_pixel_correlation_matrix_mismatch():
wcs_in = WCS(naxis=2)
wcs_in.wcs.ctype = 'RA---TAN', 'DEC--TAN'
wcs_in.wcs.set()
wcs_out = WCS(naxis=3)
wcs_out.wcs.ctype = 'DEC--TAN', 'FREQ', 'RA---TAN'
wcs_out.wcs.set()
with pytest.raises(ValueError) as exc:
_pixel_to_pixel_correlation_matrix(wcs_in, wcs_out)
assert exc.value.args[0] == "The two WCS return a different number of world coordinates"
wcs3 = WCS(naxis=2)
wcs3.wcs.ctype = 'FREQ', 'PIXEL'
wcs3.wcs.set()
with pytest.raises(ValueError) as exc:
_pixel_to_pixel_correlation_matrix(wcs_out, wcs3)
assert exc.value.args[0] == "The world coordinate types of the two WCS do not match"
wcs4 = WCS(naxis=4)
wcs4.wcs.ctype = 'RA---TAN', 'DEC--TAN', 'Q1', 'Q2'
wcs4.wcs.cunit = ['deg', 'deg', 'm/s', 'm/s']
wcs4.wcs.set()
wcs5 = WCS(naxis=4)
wcs5.wcs.ctype = 'Q1', 'RA---TAN', 'DEC--TAN', 'Q2'
wcs5.wcs.cunit = ['m/s', 'deg', 'deg', 'm/s']
wcs5.wcs.set()
with pytest.raises(ValueError) as exc:
_pixel_to_pixel_correlation_matrix(wcs4, wcs5)
assert exc.value.args[0] == "World coordinate order doesn't match and automatic matching is ambiguous"
def test_pixel_to_pixel_correlation_matrix_spectral_cube_correlated():
# NOTE: only make one of the WCSes have correlated axes to really test this
wcs_in = WCS(naxis=3)
wcs_in.wcs.ctype = 'RA---TAN', 'DEC--TAN', 'FREQ'
wcs_in.wcs.set()
wcs_out = WCS(naxis=3)
wcs_out.wcs.ctype = 'DEC--TAN', 'FREQ', 'RA---TAN'
wcs_out.wcs.cd = np.ones((3, 3))
wcs_out.wcs.set()
matrix = _pixel_to_pixel_correlation_matrix(wcs_in, wcs_out)
assert_equal(matrix, [[1, 1, 1], [1, 1, 1], [1, 1, 1]])
