def test_polarisation_frame_from_wcs(self):
assert self.m31image.polarisation_frame == PolarisationFrame("stokesI")
stokes = create_test_image(
cellsize=0.0001,
polarisation_frame=PolarisationFrame("stokesIQUV"))
wcs = stokes.wcs.deepcopy()
shape = stokes.shape
assert polarisation_frame_from_wcs(
wcs, shape) == PolarisationFrame("stokesIQUV")
wcs = stokes.wcs.deepcopy().sub(['stokes'])
wcs.wcs.crpix[0] = 1.0
wcs.wcs.crval[0] = -1.0
wcs.wcs.cdelt[0] = -1.0
assert polarisation_frame_from_wcs(
wcs, shape) == PolarisationFrame('circular')
wcs.wcs.crpix[0] = 1.0
wcs.wcs.crval[0] = -5.0
wcs.wcs.cdelt[0] = -1.0
assert polarisation_frame_from_wcs(
wcs, shape) == PolarisationFrame('linear')
wcs.wcs.crpix[0] = 1.0
wcs.wcs.crval[0] = -1.0
wcs.wcs.cdelt[0] = -1.0
assert polarisation_frame_from_wcs(
wcs, shape) == PolarisationFrame('circular')
with self.assertRaises(ValueError):
wcs.wcs.crpix[0] = 1.0
wcs.wcs.crval[0] = -100.0
wcs.wcs.cdelt[0] = -1.0
pf = polarisation_frame_from_wcs(wcs, shape)
def test_stokes_conversion(self):
assert self.m31image.polarisation_frame == PolarisationFrame("stokesI")
stokes = create_test_image(cellsize=0.0001, polarisation_frame=PolarisationFrame("stokesIQUV"))
assert stokes.polarisation_frame == PolarisationFrame("stokesIQUV")
for pol_name in ['circular', 'linear']:
polarisation_frame = PolarisationFrame(pol_name)
polimage = convert_stokes_to_polimage(stokes, polarisation_frame=polarisation_frame)
assert polimage.polarisation_frame == polarisation_frame
polarisation_frame_from_wcs(polimage.wcs, polimage.shape)
rstokes = convert_polimage_to_stokes(polimage)
assert polimage.data.dtype == 'complex'
assert rstokes.data.dtype == 'complex'
numpy.testing.assert_array_almost_equal(stokes.data, rstokes.data.real, 12)