def sample_coord(self, map_coord, random_state=0):
"""Apply the energy dispersion corrections on the coordinates of a set of simulated events.
Parameters
----------
map_coord : `~gammapy.maps.MapCoord` object.
Sequence of coordinates and energies of sampled events.
random_state : {int, 'random-seed', 'global-rng', `~numpy.random.RandomState`}
Defines random number generator initialisation.
Passed to `~gammapy.utils.random.get_random_state`.
Returns
-------
`~gammapy.maps.MapCoord`.
Sequence of Edisp-corrected coordinates of the input map_coord map.
"""
random_state = get_random_state(random_state)
migra_axis = self.edisp_map.geom.get_axis_by_name("migra")
coord = {
"skycoord": map_coord.skycoord.reshape(-1, 1),
"energy_true": map_coord["energy_true"].reshape(-1, 1),
"migra": migra_axis.center,
}
pdf_edisp = self.edisp_map.interp_by_coord(coord)
sample_edisp = InverseCDFSampler(pdf_edisp, axis=1, random_state=random_state)
pix_edisp = sample_edisp.sample_axis()
migra = migra_axis.pix_to_coord(pix_edisp)
energy_reco = map_coord["energy_true"] * migra
return MapCoord.create({"skycoord": map_coord.skycoord, "energy": energy_reco})
def test_axis_sampling():
n_sampled = 1000
x = np.linspace(-2, 2, n_sampled)
a, b = -1, 1
pdf_uniform = uniform_dist(x, a=a, b=b)
mu, sigma = 0, 0.1
pdf_gauss = gauss_dist(x=x, mu=mu, sigma=sigma)
pdf = np.vstack([pdf_gauss, pdf_uniform])
sampler = InverseCDFSampler(pdf, random_state=0, axis=1)
idx = sampler.sample_axis()
x_sampled = np.interp(idx, np.arange(n_sampled), x)
assert_allclose(x_sampled, [0.01042147, 0.43061014], rtol=1e-5)
def sample_coord(self, map_coord, random_state=0):
"""Apply PSF corrections on the coordinates of a set of simulated events.
Parameters
----------
map_coord : `~gammapy.maps.MapCoord` object.
Sequence of coordinates and energies of sampled events.
random_state : {int, 'random-seed', 'global-rng', `~numpy.random.RandomState`}
Defines random number generator initialisation.
Passed to `~gammapy.utils.random.get_random_state`.
Returns
-------
corr_coord : `~gammapy.maps.MapCoord` object.
Sequence of PSF-corrected coordinates of the input map_coord map.
"""
random_state = get_random_state(random_state)
rad_axis = self.psf_map.geom.axes["rad"]
coord = {
"skycoord": map_coord.skycoord.reshape(-1, 1),
"energy_true": map_coord["energy_true"].reshape(-1, 1),
"rad": rad_axis.center,
}
pdf = (
self.psf_map.interp_by_coord(coord)
* rad_axis.center.value
* rad_axis.bin_width.value
)
sample_pdf = InverseCDFSampler(pdf, axis=1, random_state=random_state)
pix_coord = sample_pdf.sample_axis()
separation = rad_axis.pix_to_coord(pix_coord)
position_angle = random_state.uniform(360, size=len(map_coord.lon)) * u.deg
event_positions = map_coord.skycoord.directional_offset_by(
position_angle=position_angle, separation=separation
)
return MapCoord.create(
{"skycoord": event_positions, "energy_true": map_coord["energy_true"]}
)