# Licensed under a 3-clause BSD style license - see LICENSE.rst
import numpy as np
from astropy import units as u
from astropy.coordinates import Angle
from astropy.io import fits
from astropy.table import Table
from astropy.utils import lazyproperty
from gammapy.utils.array import array_stats_str
from gammapy.utils.energy import energy_logspace
from gammapy.utils.interpolation import ScaledRegularGridInterpolator
from gammapy.utils.scripts import make_path
from .psf_table import EnergyDependentTablePSF, TablePSF
__all__ = ["PSF3D"]
[docs]class PSF3D:
"""PSF with axes: energy, offset, rad.
Data format specification: :ref:`gadf:psf_table`
Parameters
----------
energy_lo : `~astropy.units.Quantity`
Energy bins lower edges (1-dim)
energy_hi : `~astropy.units.Quantity`
Energy bins upper edges (1-dim)
offset : `~astropy.coordinates.Angle`
Offset angle (1-dim)
rad_lo : `~astropy.coordinates.Angle`
Offset angle bins lower edges
rad_hi : `~astropy.coordinates.Angle`
Offset angle bins upper edges
psf_value : `~astropy.units.Quantity`
PSF (3-dim with axes: psf[rad_index, offset_index, energy_index]
energy_thresh_lo : `~astropy.units.Quantity`
Lower energy threshold.
energy_thresh_hi : `~astropy.units.Quantity`
Upper energy threshold.
"""
def __init__(
self,
energy_lo,
energy_hi,
offset,
rad_lo,
rad_hi,
psf_value,
energy_thresh_lo=u.Quantity(0.1, "TeV"),
energy_thresh_hi=u.Quantity(100, "TeV"),
interp_kwargs=None,
):
self.energy_lo = energy_lo.to("TeV")
self.energy_hi = energy_hi.to("TeV")
self.offset = Angle(offset)
self.rad_lo = Angle(rad_lo)
self.rad_hi = Angle(rad_hi)
self.psf_value = psf_value.to("sr^-1")
self.energy_thresh_lo = energy_thresh_lo.to("TeV")
self.energy_thresh_hi = energy_thresh_hi.to("TeV")
self._interp_kwargs = interp_kwargs or {}
@lazyproperty
def _interpolate(self):
energy = self._energy_logcenter()
offset = self.offset.to("deg")
rad = self._rad_center()
return ScaledRegularGridInterpolator(
points=(rad, offset, energy), values=self.psf_value, **self._interp_kwargs
)
[docs] def info(self):
"""Print some basic info.
"""
ss = "\nSummary PSF3D info\n"
ss += "---------------------\n"
ss += array_stats_str(self.energy_lo, "energy_lo")
ss += array_stats_str(self.energy_hi, "energy_hi")
ss += array_stats_str(self.offset, "offset")
ss += array_stats_str(self.rad_lo, "rad_lo")
ss += array_stats_str(self.rad_hi, "rad_hi")
ss += array_stats_str(self.psf_value, "psf_value")
# TODO: should quote containment values also
return ss
def _energy_logcenter(self):
"""Get logcenters of energy bins.
Returns
-------
energies : `~astropy.units.Quantity`
Logcenters of energy bins
"""
return np.sqrt(self.energy_lo * self.energy_hi)
def _rad_center(self):
"""Get centers of rad bins (`~astropy.coordinates.Angle` in deg).
"""
return ((self.rad_hi + self.rad_lo) / 2).to("deg")
[docs] @classmethod
def read(cls, filename, hdu="PSF_2D_TABLE"):
"""Create `PSF3D` from FITS file.
Parameters
----------
filename : str
File name
hdu : str
HDU name
"""
filename = str(make_path(filename))
table = Table.read(filename, hdu=hdu)
return cls.from_table(table)
[docs] @classmethod
def from_table(cls, table):
"""Create `PSF3D` from `~astropy.table.Table`.
Parameters
----------
table : `~astropy.table.Table`
Table Table-PSF info.
"""
theta_lo = table["THETA_LO"].quantity[0]
theta_hi = table["THETA_HI"].quantity[0]
offset = (theta_hi + theta_lo) / 2
offset = Angle(offset, unit=table["THETA_LO"].unit)
energy_lo = table["ENERG_LO"].quantity[0]
energy_hi = table["ENERG_HI"].quantity[0]
rad_lo = table["RAD_LO"].quantity[0]
rad_hi = table["RAD_HI"].quantity[0]
psf_value = table["RPSF"].quantity[0]
opts = {}
try:
opts["energy_thresh_lo"] = u.Quantity(table.meta["LO_THRES"], "TeV")
opts["energy_thresh_hi"] = u.Quantity(table.meta["HI_THRES"], "TeV")
except KeyError:
pass
return cls(energy_lo, energy_hi, offset, rad_lo, rad_hi, psf_value, **opts)
[docs] def to_fits(self):
"""
Convert PSF table data to FITS HDU list.
Returns
-------
hdu_list : `~astropy.io.fits.HDUList`
PSF in HDU list format.
"""
# Set up data
names = [
"ENERG_LO",
"ENERG_HI",
"THETA_LO",
"THETA_HI",
"RAD_LO",
"RAD_HI",
"RPSF",
]
units = ["TeV", "TeV", "deg", "deg", "deg", "deg", "sr^-1"]
data = [
self.energy_lo,
self.energy_hi,
self.offset,
self.offset,
self.rad_lo,
self.rad_hi,
self.psf_value,
]
table = Table()
for name_, data_, unit_ in zip(names, data, units):
table[name_] = [data_]
table[name_].unit = unit_
hdu = fits.BinTableHDU(table)
hdu.header["LO_THRES"] = self.energy_thresh_lo.value
hdu.header["HI_THRES"] = self.energy_thresh_hi.value
return fits.HDUList([fits.PrimaryHDU(), hdu])
[docs] def write(self, filename, *args, **kwargs):
"""Write PSF to FITS file.
Calls `~astropy.io.fits.HDUList.writeto`, forwarding all arguments.
"""
self.to_fits().writeto(filename, *args, **kwargs)
[docs] def evaluate(self, energy=None, offset=None, rad=None):
"""Interpolate PSF value at a given offset and energy.
Parameters
----------
energy : `~astropy.units.Quantity`
energy value
offset : `~astropy.coordinates.Angle`
Offset in the field of view
rad : `~astropy.coordinates.Angle`
Offset wrt source position
Returns
-------
values : `~astropy.units.Quantity`
Interpolated value
"""
if energy is None:
energy = self._energy_logcenter()
if offset is None:
offset = self.offset
if rad is None:
rad = self._rad_center()
rad = np.atleast_1d(u.Quantity(rad))
offset = np.atleast_1d(u.Quantity(offset))
energy = np.atleast_1d(u.Quantity(energy))
return self._interpolate(
(
rad[:, np.newaxis, np.newaxis],
offset[np.newaxis, :, np.newaxis],
energy[np.newaxis, np.newaxis, :],
)
)
[docs] def to_energy_dependent_table_psf(self, theta="0 deg", rad=None, exposure=None):
"""
Convert PSF3D in EnergyDependentTablePSF.
Parameters
----------
theta : `~astropy.coordinates.Angle`
Offset in the field of view
rad : `~astropy.coordinates.Angle`
Offset from PSF center used for evaluating the PSF on a grid.
Default is the ``rad`` from this PSF.
exposure : `~astropy.units.Quantity`
Energy dependent exposure. Should be in units equivalent to 'cm^2 s'.
Default exposure = 1.
Returns
-------
table_psf : `~gammapy.irf.EnergyDependentTablePSF`
Energy-dependent PSF
"""
theta = Angle(theta)
energies = self._energy_logcenter()
if rad is None:
rad = self._rad_center()
else:
rad = Angle(rad)
psf_value = self.evaluate(offset=theta, rad=rad).squeeze()
return EnergyDependentTablePSF(
energy=energies, rad=rad, exposure=exposure, psf_value=psf_value.T
)
[docs] def to_table_psf(self, energy, theta="0 deg", **kwargs):
"""Create `~gammapy.irf.TablePSF` at one given energy.
Parameters
----------
energy : `~astropy.units.Quantity`
Energy
theta : `~astropy.coordinates.Angle`
Offset in the field of view. Default theta = 0 deg
Returns
-------
psf : `~gammapy.irf.TablePSF`
Table PSF
"""
energy = u.Quantity(energy)
theta = Angle(theta)
psf_value = self.evaluate(energy, theta).squeeze()
rad = self._rad_center()
return TablePSF(rad, psf_value, **kwargs)
[docs] def containment_radius(
self, energy, theta="0 deg", fraction=0.68, interp_kwargs=None
):
"""Containment radius.
Parameters
----------
energy : `~astropy.units.Quantity`
Energy
theta : `~astropy.coordinates.Angle`
Offset in the field of view. Default theta = 0 deg
fraction : float
Containment fraction. Default fraction = 0.68
Returns
-------
radius : `~astropy.units.Quantity`
Containment radius in deg
"""
energy = np.atleast_1d(u.Quantity(energy))
theta = np.atleast_1d(u.Quantity(theta))
radii = []
for t in theta:
psf = self.to_energy_dependent_table_psf(theta=t)
radii.append(psf.containment_radius(energy, fraction=fraction))
return u.Quantity(radii).T.squeeze()
[docs] def plot_containment_vs_energy(
self, fractions=[0.68, 0.95], thetas=Angle([0, 1], "deg"), ax=None
):
"""Plot containment fraction as a function of energy.
"""
import matplotlib.pyplot as plt
ax = plt.gca() if ax is None else ax
energy = energy_logspace(self.energy_lo[0], self.energy_hi[-1], 100)
for theta in thetas:
for fraction in fractions:
radius = self.containment_radius(energy, theta, fraction)
label = f"{theta.deg} deg, {100 * fraction:.1f}%"
ax.plot(energy.value, radius.value, label=label)
ax.semilogx()
ax.legend(loc="best")
ax.set_xlabel("Energy (TeV)")
ax.set_ylabel("Containment radius (deg)")
[docs] def plot_psf_vs_rad(self, theta="0 deg", energy=u.Quantity(1, "TeV")):
"""Plot PSF vs rad.
Parameters
----------
energy : `~astropy.units.Quantity`
Energy. Default energy = 1 TeV
theta : `~astropy.coordinates.Angle`
Offset in the field of view. Default theta = 0 deg
"""
theta = Angle(theta)
table = self.to_table_psf(energy=energy, theta=theta)
return table.plot_psf_vs_rad()
[docs] def plot_containment(
self, fraction=0.68, ax=None, show_safe_energy=False, add_cbar=True, **kwargs
):
"""
Plot containment image with energy and theta axes.
Parameters
----------
fraction : float
Containment fraction between 0 and 1.
add_cbar : bool
Add a colorbar
"""
import matplotlib.pyplot as plt
ax = plt.gca() if ax is None else ax
energy = self._energy_logcenter()
offset = self.offset
# Set up and compute data
containment = self.containment_radius(energy, offset, fraction)
# plotting defaults
kwargs.setdefault("cmap", "GnBu")
kwargs.setdefault("vmin", np.nanmin(containment.value))
kwargs.setdefault("vmax", np.nanmax(containment.value))
# Plotting
x = energy.value
y = offset.value
caxes = ax.pcolormesh(x, y, containment.value.T, **kwargs)
# Axes labels and ticks, colobar
ax.semilogx()
ax.set_ylabel(f"Offset ({offset.unit})")
ax.set_xlabel(f"Energy ({energy.unit})")
ax.set_xlim(x.min(), x.max())
ax.set_ylim(y.min(), y.max())
if show_safe_energy:
self._plot_safe_energy_range(ax)
if add_cbar:
label = f"Containment radius R{100 * fraction:.0f} ({containment.unit})"
ax.figure.colorbar(caxes, ax=ax, label=label)
return ax
def _plot_safe_energy_range(self, ax):
"""add safe energy range lines to the plot"""
esafe = self.energy_thresh_lo
omin = self.offset.value.min()
omax = self.offset.value.max()
ax.hlines(y=esafe.value, xmin=omin, xmax=omax)
label = f"Safe energy threshold: {esafe:3.2f}"
ax.text(x=0.1, y=0.9 * esafe.value, s=label, va="top")
[docs] def peek(self, figsize=(15, 5)):
"""Quick-look summary plots."""
import matplotlib.pyplot as plt
fig, axes = plt.subplots(nrows=1, ncols=3, figsize=figsize)
self.plot_containment(fraction=0.68, ax=axes[0])
self.plot_containment(fraction=0.95, ax=axes[1])
self.plot_containment_vs_energy(ax=axes[2])
# TODO: implement this plot
# psf = self.psf_at_energy_and_theta(energy='1 TeV', theta='1 deg')
# psf.plot_components(ax=axes[2])
plt.tight_layout()