def test_create_gaintable_from_rows_makecopy(self):
self.actualSetup('stokesIQUV', 'linear')
gt = create_gaintable_from_blockvisibility(self.vis, timeslice='auto')
rows = gt.time > 150.0
for makecopy in [True, False]:
selected_gt = create_gaintable_from_rows(gt, rows, makecopy=makecopy)
assert selected_gt.ntimes == numpy.sum(numpy.array(rows))
def plot_gaintable_on_screen(vis,
gaintables,
height=3e5,
gaintable_slices=None,
plotfile=None):
""" Plot a gaintable on an ionospheric screen
:param vis:
:param sc: Sky components for which pierce points are needed
:param height: Height (in m) of screen above telescope e.g. 3e5
:param scale: Multiply the screen by this factor
:return: gridded screen image, weights image
"""
import matplotlib.pyplot as plt
assert isinstance(vis, BlockVisibility)
station_locations = vis.configuration.xyz
t2r = numpy.pi / 43200.0
# The time in the Visibility is hour angle in seconds!
plt.clf()
for gaintable in gaintables:
for iha, rows in enumerate(
gaintable_timeslice_iter(gaintable,
gaintable_slices=gaintable_slices)):
gt = create_gaintable_from_rows(gaintable, rows)
ha = numpy.average(gt.time)
pp = find_pierce_points(station_locations,
(gt.phasecentre.ra.rad + t2r * ha) * u.rad,
gt.phasecentre.dec,
height=height,
phasecentre=vis.phasecentre)
phases = numpy.angle(gt.gain[0, :, 0, 0, 0])
plt.scatter(pp[:, 0],
pp[:, 1],
c=phases,
cmap='hsv',
alpha=0.75,
s=0.1)
plt.title('Pierce point phases')
plt.xlabel('X (m)')
plt.ylabel('Y (m)')
if plotfile is not None:
plt.savefig(plotfile)
plt.show()
def grid_gaintable_to_screen(vis,
gaintables,
screen,
height=3e5,
gaintable_slices=None,
scale=1.0,
**kwargs):
""" Grid a gaintable to a screen image
The phases are just average per grid cell, no phase unwrapping is performed.
:param vis:
:param sc: Sky components for which pierce points are needed
:param screen:
:param height: Height (in m) of screen above telescope e.g. 3e5
:param scale: Multiply the screen by this factor
:return: gridded screen image, weights image
"""
assert isinstance(vis, BlockVisibility)
station_locations = vis.configuration.xyz
nant = station_locations.shape[0]
t2r = numpy.pi / 43200.0
newscreen = create_empty_image_like(screen)
weights = create_empty_image_like(screen)
nchan, ntimes, ny, nx = screen.shape
# The time in the Visibility is hour angle in seconds!
number_no_weight = 0
for gaintable in gaintables:
for iha, rows in enumerate(
gaintable_timeslice_iter(gaintable,
gaintable_slices=gaintable_slices)):
gt = create_gaintable_from_rows(gaintable, rows)
ha = numpy.average(gt.time)
pp = find_pierce_points(station_locations,
(gt.phasecentre.ra.rad + t2r * ha) * u.rad,
gt.phasecentre.dec,
height=height,
phasecentre=vis.phasecentre)
scr = numpy.angle(gt.gain[0, :, 0, 0, 0])
wt = gt.weight[0, :, 0, 0, 0]
for ant in range(nant):
pp0 = pp[ant][0:2]
worldloc = [pp0[0], pp0[1], ha, 1e8]
pixloc = newscreen.wcs.wcs_world2pix([worldloc],
0)[0].astype('int')
assert pixloc[0] >= 0
assert pixloc[0] < nx
assert pixloc[1] >= 0
assert pixloc[1] < ny
newscreen.data[pixloc[3], pixloc[2], pixloc[1],
pixloc[0]] += wt[ant] * scr[ant]
weights.data[pixloc[3], pixloc[2], pixloc[1],
pixloc[0]] += wt[ant]
if wt[ant] == 0.0:
number_no_weight += 1
if number_no_weight > 0:
print("grid_gaintable_to_screen: %d pierce points are have no weight" %
(number_no_weight))
log.warning(
"grid_gaintable_to_screen: %d pierce points are have no weight" %
(number_no_weight))
newscreen.data[weights.data > 0.0] = newscreen.data[
weights.data > 0.0] / weights.data[weights.data > 0.0]
return newscreen, weights