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test_beam.py
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test_beam.py
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# Licensed under a 3-clause BSD style license - see LICENSE.rst
import pytest
from ..beam import Beam
from astropy.io import fits
from astropy import units as u
import os
import numpy as np
import numpy.testing as npt
from astropy.tests.helper import assert_quantity_allclose
from itertools import product
try:
from taskinit import ia
HAS_CASA = True
except ImportError:
HAS_CASA = False
data_dir = os.path.join(os.path.dirname(__file__), 'data')
def data_path(filename):
return os.path.join(data_dir, filename)
def test_classic_header():
# Instantiate from header
fname = data_path("NGC0925.bima.mmom0.fits.gz")
hdr = fits.getheader(fname)
bima_beam_file = Beam.from_fits_header(fname)
npt.assert_equal(bima_beam_file.major.value, hdr["BMAJ"])
npt.assert_equal(bima_beam_file.minor.value, hdr["BMIN"])
npt.assert_equal(bima_beam_file.pa.value, hdr["BPA"])
bima_beam_hdr = Beam.from_fits_header(hdr)
npt.assert_equal(bima_beam_hdr.major.value, hdr["BMAJ"])
npt.assert_equal(bima_beam_hdr.minor.value, hdr["BMIN"])
npt.assert_equal(bima_beam_hdr.pa.value, hdr["BPA"])
def test_from_aips_test():
aips_fname = data_path("ngc0925_na.fits.gz")
aips_hdr = fits.getheader(aips_fname)
aips_beam_hdr = Beam.from_fits_header(aips_hdr)
npt.assert_almost_equal(aips_beam_hdr.sr.value, 9.029858054819811e-10)
aips_beam_file = Beam.from_fits_header(aips_fname)
npt.assert_almost_equal(aips_beam_file.sr.value, 9.029858054819811e-10)
def test_fits_from_casa():
casa_fname = data_path("m83.moment0.fits.gz")
casa_hdr = fits.getheader(casa_fname)
casa_beam_hdr = Beam.from_fits_header(casa_hdr)
npt.assert_almost_equal(casa_beam_hdr.sr.value, 2.98323984597532e-11)
casa_beam_file = Beam.from_fits_header(casa_fname)
npt.assert_almost_equal(casa_beam_file.sr.value, 2.98323984597532e-11)
def test_manual():
# Instantiate from command line
man_beam_val = Beam(0.1, 0.1, 30)
npt.assert_almost_equal(man_beam_val.value, 3.451589629868801e-06)
man_beam_rad = Beam(0.1*u.rad, 0.1*u.rad, 30*u.deg)
npt.assert_almost_equal(man_beam_rad.value, 0.011330900354567986)
man_beam_deg = Beam(0.1*u.deg, 0.1*u.deg, 1.0*u.rad)
npt.assert_almost_equal(man_beam_deg.value, 3.451589629868801e-06)
def test_bintable():
beams = np.recarray(4, dtype=[('BMAJ', '>f4'), ('BMIN', '>f4'),
('BPA', '>f4'), ('CHAN', '>i4'),
('POL', '>i4')])
beams['BMIN'] = [0.1,0.1001,0.09999,0.099999] # arcseconds
beams['BMAJ'] = [0.2,0.2001,0.1999,0.19999]
beams['BPA'] = [45.1,45.101,45.102,45.099] # degrees
beams['CHAN'] = [0,0,0,0]
beams['POL'] = [0,0,0,0]
beams = fits.BinTableHDU(beams)
beam = Beam.from_fits_bintable(beams)
npt.assert_almost_equal(beam.minor.to(u.arcsec).value,
0.10002226, decimal=4)
npt.assert_almost_equal(beam.major.to(u.arcsec).value,
0.19999751, decimal=4)
npt.assert_almost_equal(beam.pa.to(u.deg).value,
45.10050065568665, decimal=4)
@pytest.mark.skipif("not HAS_CASA")
def test_from_casa_image():
# Extract from tar
import tarfile
fname_tar = data_path("NGC0925.bima.mmom0.image.tar.gz")
tar = tarfile.open(fname_tar)
tar.extractall(path=data_dir)
tar.close()
fname = data_path("NGC0925.bima.mmom0.image")
bima_casa_beam = Beam.from_casa_image(fname)
def test_attach_to_header():
fname = data_path("NGC0925.bima.mmom0.fits.gz")
hdr = fits.getheader(fname)
hdr_copy = hdr.copy()
del hdr_copy["BMAJ"], hdr_copy["BMIN"], hdr_copy["BPA"]
bima_beam = Beam.from_fits_header(fname)
new_hdr = bima_beam.attach_to_header(hdr_copy)
npt.assert_equal(new_hdr["BMAJ"], hdr["BMAJ"])
npt.assert_equal(new_hdr["BMIN"], hdr["BMIN"])
npt.assert_equal(new_hdr["BPA"], hdr["BPA"])
def test_beam_projected_area():
distance = 250 * u.pc
major = 0.1 * u.rad
beam = Beam(major, major, 30 * u.deg)
beam_sr = (major**2 * 2 * np.pi / (8 * np.log(2))).to(u.sr)
assert_quantity_allclose(beam_sr.value * distance ** 2,
beam.beam_projected_area(distance))
def test_jtok():
major = 0.1 * u.rad
beam = Beam(major, major, 30 * u.deg)
freq = 1.42 * u.GHz
conv_factor = u.brightness_temperature(beam.sr, freq)
assert_quantity_allclose((1 * u.Jy).to(u.K, equivalencies=conv_factor),
beam.jtok(freq))
def test_jtok_equiv():
major = 0.1 * u.rad
beam = Beam(major, major, 30 * u.deg)
freq = 1.42 * u.GHz
conv_factor = u.brightness_temperature(beam.sr, freq)
conv_beam_factor = beam.jtok_equiv(freq)
assert_quantity_allclose((1 * u.Jy).to(u.K, equivalencies=conv_factor),
(1 * u.Jy).to(u.K, equivalencies=conv_beam_factor))
assert_quantity_allclose((1 * u.K).to(u.Jy, equivalencies=conv_factor),
(1 * u.K).to(u.Jy, equivalencies=conv_beam_factor))
def test_convolution():
# equations from:
# https://github.com/pkgw/carma-miriad/blob/CVSHEAD/src/subs/gaupar.for
# (github checkin of MIRIAD, code by Sault)
major1 = 1 * u.deg
minor1 = 0.5 * u.deg
pa1 = 0.0 * u.deg
beam1 = Beam(major1, minor1, pa1)
major2 = 1 * u.deg
minor2 = 0.75 * u.deg
pa2 = 90.0 * u.deg
beam2 = Beam(major2, minor2, pa2)
alpha = (major1 * np.cos(pa1))**2 + (minor1 * np.sin(pa1))**2 + \
(major2 * np.cos(pa2))**2 + (minor2 * np.sin(pa2))**2
beta = (major1 * np.sin(pa1))**2 + (minor1 * np.cos(pa1))**2 + \
(major2 * np.sin(pa2))**2 + (minor2 * np.cos(pa2))**2
gamma = 2 * ((minor1**2 - major1**2) * np.sin(pa1) * np.cos(pa1) +
(minor2**2 - major2**2) * np.sin(pa2) * np.cos(pa2))
s = alpha + beta
t = np.sqrt((alpha - beta)**2 + gamma**2)
conv_major = np.sqrt(0.5 * (s + t))
conv_minor = np.sqrt(0.5 * (s - t))
conv_pa = 0.5 * np.arctan2(- gamma, alpha - beta)
conv_beam = beam1.convolve(beam2)
assert_quantity_allclose(conv_major, conv_beam.major)
assert_quantity_allclose(conv_minor, conv_beam.minor)
assert_quantity_allclose(conv_pa, conv_beam.pa)
def test_deconvolution():
# equations from:
# https://github.com/pkgw/carma-miriad/blob/CVSHEAD/src/subs/gaupar.for
# (github checkin of MIRIAD, code by Sault)
major1 = 2.0 * u.deg
minor1 = 1.0 * u.deg
pa1 = 45.0 * u.deg
beam1 = Beam(major1, minor1, pa1)
major2 = 1 * u.deg
minor2 = 0.5 * u.deg
pa2 = 0.0 * u.deg
beam2 = Beam(major2, minor2, pa2)
alpha = (major1 * np.cos(pa1))**2 + (minor1 * np.sin(pa1))**2 - \
(major2 * np.cos(pa2))**2 - (minor2 * np.sin(pa2))**2
beta = (major1 * np.sin(pa1))**2 + (minor1 * np.cos(pa1))**2 - \
(major2 * np.sin(pa2))**2 - (minor2 * np.cos(pa2))**2
gamma = 2 * ((minor1**2 - major1**2) * np.sin(pa1) * np.cos(pa1) +
(minor2**2 - major2**2) * np.sin(pa2) * np.cos(pa2))
s = alpha + beta
t = np.sqrt((alpha - beta)**2 + gamma**2)
deconv_major = np.sqrt(0.5 * (s + t))
deconv_minor = np.sqrt(0.5 * (s - t))
deconv_pa = 0.5 * np.arctan2(- gamma, alpha - beta)
deconv_beam = beam1.deconvolve(beam2)
assert_quantity_allclose(deconv_major, deconv_beam.major)
assert_quantity_allclose(deconv_minor, deconv_beam.minor)
assert_quantity_allclose(deconv_pa, deconv_beam.pa)
def test_conv_deconv():
beam1 = Beam(10. * u.arcsec, 5. * u.arcsec, 30. * u.deg)
beam2 = Beam(5. * u.arcsec, 3. * u.arcsec, 120. * u.deg)
beam3 = beam1.convolve(beam2)
assert beam2 == beam3.deconvolve(beam1)
assert beam1 == beam3.deconvolve(beam2)
assert beam1.convolve(beam2) == beam2.convolve(beam1)
# Test multiplication and subtraction (i.e., convolution and deconvolution)
assert beam2 == beam3 - beam1
assert beam1 == beam3 - beam2
# Dividing should give the same thing
assert beam2 == beam3 / beam1
assert beam1 == beam3 / beam2
assert beam3 == beam1 * beam2
@pytest.mark.parametrize(('major', 'minor', 'pa', 'return_pointlike'),
[[maj, min, pa, ret] for maj, min, pa, ret in
product([10], np.arange(1, 11),
np.linspace(0, 180, 10), [True, False])])
def test_deconv_pointlike(major, minor, pa, return_pointlike):
beam1 = Beam(major * u.arcsec, major * u.arcsec, pa * u.deg)
if return_pointlike:
point_beam = Beam(0 * u.deg, 0 * u.deg, 0 * u.deg)
point_beam == beam1.deconvolve(beam1, failure_returns_pointlike=True)
else:
try:
beam1.deconvolve(beam1, failure_returns_pointlike=False)
except ValueError:
pass
def test_isfinite():
beam1 = Beam(10. * u.arcsec, 5. * u.arcsec, 30. * u.deg)
assert beam1.isfinite
beam2 = Beam(-10. * u.arcsec, 5. * u.arcsec, 30. * u.deg)
assert not beam2.isfinite
beam3 = Beam(10. * u.arcsec, -5. * u.arcsec, 30. * u.deg)
assert not beam3.isfinite
@pytest.mark.parametrize(("major", "minor", "pa"),
[(10, 10, 60),
(10, 10, -120),
(10, 10, -300),
(10, 10, 240),
(10, 10, 59),
(10, 10, -121)])
def test_beam_equal(major, minor, pa):
beam1 = Beam(10 * u.deg, 10 * u.deg, 60 * u.deg)
beam2 = Beam(major * u.deg, minor * u.deg, pa * u.deg)
assert beam1 == beam2
assert not beam1 != beam2
@pytest.mark.parametrize(("major", "minor", "pa"),
[(10, 8, 60),
(10, 8, -120),
(10, 8, 240)])
def test_beam_equal_noncirc(major, minor, pa):
'''
Beams with PA +/- 180 deg are equal
'''
beam1 = Beam(10 * u.deg, 8 * u.deg, 60 * u.deg)
beam2 = Beam(major * u.deg, minor * u.deg, pa * u.deg)
assert beam1 == beam2
assert not beam1 != beam2
@pytest.mark.parametrize(("major", "minor", "pa"),
[(10, 8, 60),
(12, 10, 60),
(12, 10, 59)])
def test_beam_not_equal(major, minor, pa):
beam1 = Beam(10 * u.deg, 10 * u.deg, 60 * u.deg)
beam2 = Beam(major * u.deg, minor * u.deg, pa * u.deg)
assert beam1 != beam2
def test_from_aips_issue43():
""" regression test for issue 43 """
aips_fname = data_path("header_aips.hdr")
aips_hdr = fits.Header.fromtextfile(aips_fname)
aips_beam_hdr = Beam.from_fits_header(aips_hdr)
npt.assert_almost_equal(aips_beam_hdr.pa.value, -15.06)
def test_small_beam_convolution():
# regression test for #68
beam1 = Beam((0.1*u.arcsec).to(u.deg), (0.00001*u.arcsec).to(u.deg), 30*u.deg)
beam2 = Beam((0.3*u.arcsec).to(u.deg), (0.00001*u.arcsec).to(u.deg), 120*u.deg)
conv = beam1.convolve(beam2)
np.testing.assert_almost_equal(conv.pa.to(u.deg).value, -60)