def to_energy_dependent_table_psf(self, offset, rad=None):
"""Convert to energy-dependent table PSF.
Parameters
----------
offset : `~astropy.coordinates.Angle`
Offset in the field of view. Default theta = 0 deg
rad : `~astropy.coordinates.Angle`
Offset from PSF center used for evaluating the PSF on a grid.
Default offset = [0, 0.005, ..., 1.495, 1.5] deg.
Returns
-------
table_psf : `~gammapy.irf.EnergyDependentTablePSF`
Energy-dependent PSF
"""
from gammapy.irf import EnergyDependentTablePSF
from gammapy.datasets.map import RAD_AXIS_DEFAULT
energy_axis_true = self.axes["energy_true"]
if rad is None:
rad_axis = RAD_AXIS_DEFAULT
else:
rad_axis = MapAxis.from_edges(rad, name="rad")
axes = MapAxes([energy_axis_true, rad_axis])
data = self.evaluate(**axes.get_coord(), offset=offset)
return EnergyDependentTablePSF(axes=axes,
data=data.value,
unit=data.unit)
def get_energy_dependent_table_psf(self, position):
"""Get energy-dependent PSF at a given position.
Parameters
----------
position : `~astropy.coordinates.SkyCoord`
the target position. Should be a single coordinates
Returns
-------
psf_table : `~gammapy.irf.EnergyDependentTablePSF`
the table PSF
"""
if position.size != 1:
raise ValueError(
"EnergyDependentTablePSF can be extracted at one single position only."
)
# axes ordering fixed. Could be changed.
pix_ener = np.arange(self.psf_map.geom.axes[1].nbin)
pix_rad = np.arange(self.psf_map.geom.axes[0].nbin)
# Convert position to pixels
pix_lon, pix_lat = self.psf_map.geom.to_image().coord_to_pix(position)
# Build the pixels tuple
pix = np.meshgrid(pix_lon, pix_lat, pix_rad, pix_ener)
# Interpolate in the PSF map. Squeeze to remove dimensions of length 1
psf_values = np.squeeze(
self.psf_map.interp_by_pix(pix) * u.Unit(self.psf_map.unit)
)
energies = self.psf_map.geom.axes[1].center
rad = self.psf_map.geom.axes[0].center
if self.exposure_map is not None:
exposure_3d = self.exposure_map.slice_by_idx({"theta": 0})
coords = {
"skycoord": position,
"energy": energies.reshape((-1, 1, 1))
}
data = exposure_3d.interp_by_coord(coords).squeeze()
exposure = data * self.exposure_map.unit
else:
exposure = None
# Beware. Need to revert rad and energies to follow the TablePSF scheme.
return EnergyDependentTablePSF(
energy=energies,
rad=rad,
psf_value=psf_values.T,
exposure=exposure
)
def get_energy_dependent_table_psf(self, position):
"""Get energy-dependent PSF at a given position.
Parameters
----------
position : `~astropy.coordinates.SkyCoord`
the target position. Should be a single coordinates
Returns
-------
psf_table : `~gammapy.irf.EnergyDependentTablePSF`
the table PSF
"""
if position.size != 1:
raise ValueError(
"EnergyDependentTablePSF can be extracted at one single position only."
)
energy = self.psf_map.geom.get_axis_by_name("energy").center
rad = self.psf_map.geom.get_axis_by_name("theta").center
coords = {
"skycoord": position,
"energy": energy.reshape((-1, 1, 1, 1)),
"theta": rad.reshape((1, -1, 1, 1)),
}
data = self.psf_map.interp_by_coord(coords)
psf_values = u.Quantity(data[:, :, 0, 0],
unit=self.psf_map.unit,
copy=False)
if self.exposure_map is not None:
coords = {
"skycoord": position,
"energy": energy.reshape((-1, 1, 1)),
"theta": 0 * u.deg,
}
data = self.exposure_map.interp_by_coord(coords).squeeze()
exposure = data * self.exposure_map.unit
else:
exposure = None
# Beware. Need to revert rad and energies to follow the TablePSF scheme.
return EnergyDependentTablePSF(energy=energy,
rad=rad,
psf_value=psf_values,
exposure=exposure)
def test_apply_containment_fraction():
n_edges_energy = 5
energy = energy_logspace(0.1, 10.0, nbins=n_edges_energy + 1, unit="TeV")
area = np.ones(n_edges_energy) * 4 * u.m**2
aeff = EffectiveAreaTable(energy[:-1], energy[1:], data=area)
nrad = 100
rad = Angle(np.linspace(0, 0.5, nrad), "deg")
psf_table = TablePSF.from_shape(shape="disk", width="0.2 deg", rad=rad)
psf_values = (np.resize(psf_table.psf_value.value,
(n_edges_energy, nrad)) * psf_table.psf_value.unit)
edep_psf_table = EnergyDependentTablePSF(aeff.energy.center,
rad,
psf_value=psf_values)
new_aeff = apply_containment_fraction(aeff, edep_psf_table,
Angle("0.1 deg"))
assert_allclose(new_aeff.data.data.value, 1.0, rtol=5e-4)
assert new_aeff.data.data.unit == "m2"
