def test_stokes_linear_conversion(self):
stokes = numpy.array([1.0, 0.0, 0.0, 0.0])
linear = convert_stokes_to_linear(stokes)
assert_array_almost_equal(
linear, numpy.array([1.0 + 0j, 0.0 + 0j, 0.0 + 0j, 1.0 + 0j]))
stokes = numpy.array([0.0, 1.0, 0.0, 0.0])
linear = convert_stokes_to_linear(stokes)
assert_array_almost_equal(linear,
numpy.array([1.0 + 0j, 0j, 0j, -1.0 + 0j]))
stokes = numpy.array([0.0, 0.0, 1.0, 0.0])
linear = convert_stokes_to_linear(stokes)
assert_array_almost_equal(
linear, numpy.array([0.0 + 0j, 1.0 + 0j, 1.0 + 0j, 0.0 + 0j]))
stokes = numpy.array([0.0, 0.0, 0.0, 1.0])
linear = convert_stokes_to_linear(stokes)
assert_array_almost_equal(
linear, numpy.array([0.0 + 0j, +1.0j, -1.0j, 0.0 + 0j]))
def convert_stokes_to_polimage(im: Image, polarisation_frame: PolarisationFrame):
"""Convert a stokes image to polarisation_frame
"""
assert isinstance(im, Image)
assert isinstance(polarisation_frame, PolarisationFrame)
if polarisation_frame == PolarisationFrame('linear'):
cimarr = convert_stokes_to_linear(im.data)
return create_image_from_array(cimarr, im.wcs, polarisation_frame)
elif polarisation_frame == PolarisationFrame('circular'):
cimarr = convert_stokes_to_circular(im.data)
return create_image_from_array(cimarr, im.wcs, polarisation_frame)
else:
raise ValueError("Cannot convert stokes to %s" % (polarisation_frame.type))
def test_stokes_linear_stokes_conversion(self):
stokes = numpy.array([1, 0.5, 0.2, -0.1])
linear = convert_stokes_to_linear(stokes)
assert_array_almost_equal(
convert_linear_to_stokes(linear).real, stokes, 15)
