# Licensed under a 3-clause BSD style license - see LICENSE.rst
"""Gamma-ray spectral cube: longitude, latitude and spectral axis.
TODO: split `SkyCube` into a base class ``SkyCube`` and a few sub-classes:
* ``SkyCube`` to represent functions evaluated at grid points (diffuse model format ... what is there now).
* ``ExposureCube`` should also be supported (same semantics, but different units / methods as ``SkyCube`` (``gtexpcube`` format)
* ``SkyCubeHistogram`` to represent model or actual counts in energy bands (``gtbin`` format)
"""
from __future__ import absolute_import, division, print_function, unicode_literals
from collections import OrderedDict
import numpy as np
from numpy.testing import assert_allclose
from astropy.io import fits
import astropy.units as u
from astropy.units import Quantity
from astropy.table import Table
from astropy.wcs import WCS
from astropy.utils import lazyproperty
from ..utils.scripts import make_path
from ..utils.energy import EnergyBounds, Energy
from ..utils.fits import SmartHDUList, fits_header_to_meta_dict, table_to_fits_table
from ..image.core import SkyImage, MapBase
from ..spectrum import LogEnergyAxis
from ..spectrum.utils import _trapz_loglog
__all__ = [
'SkyCube',
]
[docs]class SkyCube(MapBase):
"""Sky cube with dimensions lon, lat and energy.
.. note::
There is a very nice ``SkyCube`` implementation here:
http://spectral-cube.readthedocs.io/en/latest/index.html
Here is some discussion if / how it could be used:
https://github.com/radio-astro-tools/spectral-cube/issues/110
For now we re-implement what we need here.
The order of the sky cube axes is defined as following:
* The ``data`` array axis order is ``(energy, lat, lon)``.
* The ``wcs`` object is a two dimensional celestial WCS with axis order ``(lon, lat)``.
Parameters
----------
name : str
Name of the cube.
data : `~numpy.ndarray`
Data array.
wcs : `~astropy.wcs.WCS`
WCS transformation object.
energy_axis : `~gammapy.spectrum.LogEnergyAxis`
Energy axis object, defining the energy transformation.
meta : `~collections.OrderedDict`
Dictionary to store meta data.
"""
def __init__(self, name=None, data=None, wcs=None, energy_axis=None, meta=None):
# TODO: check validity of inputs
self.name = name
# TODO: In gammapy SkyCube is used sometimes with ndim = 2 for cubes
# with a single energy band
if not data.ndim > 1:
raise ValueError('Dimension of the data must be ndim = 3, but is '
'ndim = {}'.format(data.ndim))
self.data = data
self.wcs = wcs
self.meta = meta
self.energy_axis = energy_axis
@lazyproperty
def _interpolate_data(self):
"""Interpolate data using `~scipy.interpolate.RegularGridInterpolator`."""
from scipy.interpolate import RegularGridInterpolator
# set up log interpolation
unit = self.data.unit
# TODO: how to deal with zero values?
log_data = np.log(self.data.value)
z = np.arange(self.data.shape[0])
y = np.arange(self.data.shape[1])
x = np.arange(self.data.shape[2])
f = RegularGridInterpolator((z, y, x), log_data, fill_value=None,
bounds_error=False)
def interpolate(z, y, x, method='linear'):
shape = z.shape
coords = np.column_stack([z.flat, y.flat, x.flat])
val = f(coords, method=method)
return Quantity(np.exp(val).reshape(shape), unit)
return interpolate
@classmethod
[docs] def read_hdu(cls, hdu_list):
"""Read sky cube from HDU list.
Parameters
----------
object_hdu : `~astropy.io.fits.ImageHDU`
Image HDU object to be read
energy_table_hdu : `~astropy.io.fits.TableHDU`
Table HDU object giving energies of each slice
of the Image HDU object_hdu
Returns
-------
sky_cube : `SkyCube`
Sky cube
"""
object_hdu = hdu_list[0]
energy_table_hdu = hdu_list[1]
data = object_hdu.data
data = Quantity(data, '1 / (cm2 MeV s sr)')
# Note: the energy axis of the FITS cube is unusable.
# We only use proj for LON, LAT and call ENERGY from the table extension
header = object_hdu.header
wcs = WCS(header)
energy = energy_table_hdu.data['Energy']
energy = Quantity(energy, 'MeV')
meta = OrderedDict(header)
return cls(data=data, wcs=wcs, energy=energy, meta=meta)
@classmethod
[docs] def read(cls, filename, format='fermi-counts'):
"""Read sky cube from FITS file.
Parameters
----------
filename : str
File name
format : {'fermi-counts', 'fermi-background', 'fermi-exposure'}
Fits file format.
Returns
-------
sky_cube : `SkyCube`
Sky cube
"""
filename = str(make_path(filename))
hdu_list = SmartHDUList.open(filename)
hdu = hdu_list.get_hdu(hdu_type='image')
header = hdu.header
wcs = WCS(header).celestial
meta = fits_header_to_meta_dict(header)
data = hdu.data
# TODO: check and give reference for fermi data units
# TODO: choose format automatically
if format == 'fermi-background':
energy = Table.read(filename, 'ENERGIES')['Energy']
energy_axis = LogEnergyAxis(Quantity(energy, 'MeV'), mode='center')
data = Quantity(data, '1 / (cm2 MeV s sr)')
name = 'flux'
elif format == 'fermi-counts':
energy = EnergyBounds.from_ebounds(fits.open(filename)['EBOUNDS'])
energy_axis = LogEnergyAxis(energy, mode='edges')
data = Quantity(data, 'count')
name = 'counts'
elif format == 'fermi-exposure':
energy = Table.read(filename, 'ENERGIES')['Energy']
energy_axis = LogEnergyAxis(Quantity(energy, 'MeV'), mode='center')
data = Quantity(data, 'cm2 s')
name = 'exposure'
else:
raise ValueError('Not a valid cube fits format')
obj = cls(name=name, data=data, wcs=wcs, energy_axis=energy_axis, meta=meta)
obj._header = header
return obj
[docs] def fill_events(self, events, weights=None):
"""Fill events (modifies ``data`` attribute).
Parameters
----------
events : `~gammapy.data.EventList`
Event list
weights : str, optional
Column to use as weights (none by default)
"""
if weights is not None:
weights = events[weights]
xx, yy = self.sky_image_ref.wcs_skycoord_to_pixel(events.radec)
zz = events.energy
bins = self.energies(mode='edges'), self.sky_image_ref._bins_pix[0], self.sky_image_ref._bins_pix[1]
data = np.histogramdd([zz, yy, xx], bins, weights=weights)[0]
self.data = self.data + data
@classmethod
[docs] def empty(cls, emin=0.5, emax=100, enumbins=10, eunit='TeV', mode='edges', **kwargs):
"""Create empty sky cube with log equal energy binning from the scratch.
Parameters
----------
emin : float
Minimum energy.
emax : float
Maximum energy.
enumbins : int
Number of energy bins.
eunit : str
Energy unit.
mode : {'edges', 'center'}
Whether emin and emax denote the bin centers or edges.
kwargs : dict
Keyword arguments passed to `~gammapy.image.SkyImage.empty` to create
the spatial part of the cube.
Examples
--------
Create an empty sky cube::
from gammapy.cube import SkyCube
cube = SkyCube.empty(nxpix=11, nypix=7, enumbins=3, mode='center',
emin=1, emax=100, eunit='TeV')
Returns
-------
empty_cube : `SkyCube`
Empty sky cube object.
"""
image = SkyImage.empty(**kwargs)
if mode == 'edges':
energy = EnergyBounds.equal_log_spacing(emin, emax, enumbins, eunit)
elif mode == 'center':
energy = Energy.equal_log_spacing(emin, emax, enumbins, eunit)
else:
raise ValueError("Not a valid mode. Choose either 'center' or 'edges'.")
energy_axis = LogEnergyAxis(energy, mode=mode)
data = Quantity(image.data * np.ones(enumbins).reshape((-1, 1, 1)), image.unit)
return cls(data=data, wcs=image.wcs, energy_axis=energy_axis)
@classmethod
[docs] def empty_like(cls, reference, energies=None, unit='', fill=0):
"""Create an empty sky cube with a given WCS and energy specification.
Parameters
----------
reference : `~gammapy.cube.SkyCube` or `~gammapy.image.SkyImage`
Reference sky cube or image.
energies : `~gammapy.utils.energy.Energy` or `~gammapy.utils.energy.EnergyBounds` (optional)
Reference energies, mandatory when a `~gammapy.image.SkyImage` is passed.
unit : str
String specifying the data units.
fill : float
Value to fill the data array with.
Examples
--------
Create an empty sky cube from an image and energy center specification::
from astropy import units as u
from gammapy.image import SkyImage
from gammapy.cube import SkyCube
from gammapy.utils.energy import Energy, EnergyBounds
# define reference image
image = SkyImage.empty(nxpix=11, nypix=7)
# define energy binning centers
energies = Energy.equal_log_spacing(1 * u.TeV, 100 * u.TeV, 3)
cube = SkyCube.empty_like(reference=image, energies=energies)
# define energy binning bounds
energies = EnergyBounds.equal_log_spacing(1 * u.TeV, 100 * u.TeV, 3)
cube = SkyCube.empty_like(reference=image, energies=energies)
Returns
-------
empty_cube : `SkyCube`
Empty sky cube object.
"""
wcs = reference.wcs.copy()
if isinstance(reference, SkyImage):
if type(energies) == Energy:
mode = 'center'
enumbins = len(energies)
elif type(energies) == EnergyBounds:
mode = 'edges'
enumbins = len(energies) - 1
else:
raise ValueError("'energies' must be instance of Energy or EnergyBounds, "
"but {} was given.".format(type(energies)))
energy_axis = LogEnergyAxis(energies, mode=mode)
data = np.ones_like(reference.data)
data = data * np.ones(enumbins).reshape((-1, 1, 1))
elif isinstance(reference, SkyCube):
energy_axis = reference.energy_axis
data = np.ones_like(reference.data.value)
else:
raise ValueError("'reference' must be instance of SkyImage or SkyCube")
return cls(data=data * fill * u.Unit(unit), wcs=wcs,
energy_axis=energy_axis)
[docs] def energies(self, mode='center'):
"""Energy coordinate vector.
Parameters
----------
mode : {'center', 'edges'}
Return coordinate values at the pixels edges or pixel centers.
Returns
-------
coordinates : `~astropy.units.Quantity`
Energy
"""
if mode == 'center':
z = np.arange(self.data.shape[0])
elif mode == 'edges':
z = np.arange(self.data.shape[0] + 1) - 0.5
return self.energy_axis.wcs_pix2world(z)
[docs] def cutout(self, position, size):
"""Cut out rectangular piece of a cube.
See `~gammapy.image.SkyImage.cutout()` for details.
"""
out = []
for energy in self.energies():
image = self.sky_image(energy)
cutout = image.cutout(position=position, size=size)
out.append(cutout.data)
data = Quantity(np.stack(out, axis=0), self.data.unit)
wcs = cutout.wcs.copy()
return self.__class__(name=self.name, data=data, wcs=wcs, meta=self.meta,
energy_axis=self.energy_axis)
[docs] def wcs_skycoord_to_pixel(self, position, energy):
"""Convert world to pixel coordinates.
Parameters
----------
position : `~astropy.coordinates.SkyCoord`
Position on the sky.
energy : `~astropy.units.Quantity`
Energy
Returns
-------
(x, y, z) : tuple
Tuple of x, y, z coordinates.
"""
x, y = self.sky_image_ref.wcs_skycoord_to_pixel(position)
z = self.energy_axis.wcs_world2pix(energy)
# TODO: check order, so that it corresponds to data axis order
return x, y, z
[docs] def wcs_pixel_to_skycoord(self, x, y, z):
"""Convert pixel to world coordinates.
Parameters
----------
x : `~numpy.ndarry`
x coordinate array
y : `~numpy.ndarry`
y coordinate array
z : `~numpy.ndarry`
z coordinate array
Returns
-------
(position, energy) : tuple
Tuple of (`~astropy.coordinates.SkyCoord`, `~astropy.units.Quantity`).
"""
position = self.sky_image_ref.wcs_pixel_to_skycoord(x, y)
energy = self.energy_axis.wcs_pix2world(z)
return position, energy
[docs] def to_sherpa_data3d(self, dstype='Data3D'):
"""Convert sky cube to sherpa `Data3D` or `Data3DInt` object.
Parameters
----------
dstype : {'Data3D', 'Data3DInt'}
Sherpa data type.
"""
from .sherpa_ import Data3D, Data3DInt
energies = self.energies(mode='edges').to("TeV").value
elo = energies[:-1]
ehi = energies[1:]
n_ebins = len(elo)
if dstype == 'Data3DInt':
coordinates = self.sky_image_ref.coordinates(mode="edges")
ra = coordinates.data.lon.degree
dec = coordinates.data.lat.degree
ra_cube_hi = np.tile(ra[0:-1, 0:-1], (n_ebins, 1, 1))
ra_cube_lo = np.tile(ra[0:-1, 1:], (n_ebins, 1, 1))
dec_cube_hi = np.tile(dec[1:, 0:-1], (n_ebins, 1, 1))
dec_cube_lo = np.tile(dec[0:-1, 0:-1], (n_ebins, 1, 1))
elo_cube = elo.reshape(n_ebins, 1, 1) * np.ones_like(ra[0:-1, 0:-1]) * u.TeV
ehi_cube = ehi.reshape(n_ebins, 1, 1) * np.ones_like(ra[0:-1, 0:-1]) * u.TeV
return Data3DInt('', elo_cube.ravel(), ra_cube_lo.ravel(), dec_cube_lo.ravel(), ehi_cube.ravel(),
ra_cube_hi.ravel(), dec_cube_hi.ravel(), self.data.value.ravel(),
self.data.value.ravel().shape)
elif dstype == 'Data3D':
coordinates = self.sky_image_ref.coordinates()
ra = coordinates.data.lon.degree
dec = coordinates.data.lat.degree
ra_cube = np.tile(ra, (n_ebins, 1, 1))
dec_cube = np.tile(dec, (n_ebins, 1, 1))
elo_cube = elo.reshape(n_ebins, 1, 1) * np.ones_like(ra) * u.TeV
ehi_cube = ehi.reshape(n_ebins, 1, 1) * np.ones_like(ra) * u.TeV
return Data3D('', elo_cube.ravel(), ehi_cube.ravel(), ra_cube.ravel(),
dec_cube.ravel(), self.data.value.ravel(),
self.data.value.ravel().shape)
else:
raise ValueError('Invalid sherpa data type.')
[docs] def sky_image(self, energy, interpolation=None):
"""Slice a 2-dim `~gammapy.image.SkyImage` from the cube at a given energy.
Parameters
----------
energy : `~astropy.units.Quantity`
Energy value
interpolation : {None, 'linear', 'nearest'}
Interpolate data values between energies. None corresponds to
'nearest', but might have advantages in performance, because
no interpolator is set up.
Returns
-------
image : `~gammapy.image.SkyImage`
2-dim sky image
"""
# TODO: should we pass something in SkyImage (we speak about meta)?
z = self.energy_axis.wcs_world2pix(energy)
if interpolation:
y = np.arange(self.data.shape[1])
x = np.arange(self.data.shape[2])
z, y, x = np.meshgrid(z, y, x, indexing='ij')
data = self._interpolate_data(z, y, x)[0]
else:
data = self.data[int(np.rint(z))].copy()
wcs = self.wcs.deepcopy() if self.wcs else None
return SkyImage(name=self.name, data=data, wcs=wcs)
[docs] def sky_image_idx(self, idx):
"""Slice a 2-dim `~gammapy.image.SkyImage` from the cube at a given index.
Parameters
----------
idx : int
Index of the sky image.
Returns
-------
image : `~gammapy.image.SkyImage`
2-dim sky image
"""
data = self.data[idx].copy()
wcs = self.wcs.deepcopy() if self.wcs else None
return SkyImage(name=self.name, data=data, wcs=wcs)
@lazyproperty
def sky_image_ref(self):
"""Empty reference `~gammapy.image.SkyImage`.
Examples
--------
Can be used to access the spatial information of the cube:
>>> from gammapy.cube import SkyCube
>>> cube = SkyCube.empty()
>>> coords = cube.sky_image_ref.coordinates()
>>> solid_angle = cube.sky_image_ref.solid_angle()
"""
wcs = self.wcs.celestial
data = np.zeros_like(self.data[0])
return SkyImage(name=self.name, data=data, wcs=wcs)
[docs] def lookup(self, position, energy, interpolation=None):
"""Lookup value in the cube at given sky position and energy.
Parameters
----------
position : `~astropy.coordinates.SkyCoord`
Position on the sky.
energy : `~astropy.units.Quantity`
Energy
interpolation : {None, 'linear', 'nearest'}
Interpolate data values between energies.
Returns
-------
value : `~astropy.units.Quantity`
Value at the given sky position and energy.
"""
# TODO: add interpolation option using NDDataArray
x, y, z = self.wcs_skycoord_to_pixel(position, energy)
if interpolation:
vals = self._interpolate_data(z, y, x)
else:
vals = self.data[np.rint(z).astype('int'), np.rint(y).astype('int'),
np.rint(x).astype('int')]
return vals
[docs] def show(self, viewer='mpl', ds9options=None, **kwargs):
"""Show sky cube in image viewer.
Parameters
----------
viewer : {'mpl', 'ds9'}
Which image viewer to use. Option 'ds9' requires ds9 to be installed.
ds9options : list, optional
List of options passed to ds9. E.g. ['-cmap', 'heat', '-scale', 'log'].
Any valid ds9 command line option can be passed.
See http://ds9.si.edu/doc/ref/command.html for details.
**kwargs : dict
Keyword arguments passed to `matplotlib.pyplot.imshow`.
"""
import matplotlib.pyplot as plt
from ipywidgets import interact
if viewer == 'mpl':
max_ = self.data.shape[0] - 1
def show_image(idx):
energy = self.energy_axis.wcs_pix2world(idx)
image = self.sky_image(energy)
image.data = image.data.value
try:
norm = kwargs['norm']
norm.vmax = np.nanmax(image.data)
except KeyError:
pass
image.show(**kwargs)
return interact(show_image, idx=(0, max_, 1))
elif viewer == 'ds9':
raise NotImplementedError
else:
raise ValueError('Invalid viewer: {}'.format(viewer))
[docs] def plot_rgb(self, ax=None, fig=None, **kwargs):
"""Plot sky cube as RGB image.
Parameters
----------
ax : `~astropy.visualization.wcsaxes.WCSAxes`, optional
WCS axis object to plot on.
fig : `~matplotlib.figure.Figure`, optional
Figure
Returns
-------
ax : `~astropy.visualization.wcsaxes.WCSAxes`
WCS axis object
"""
import matplotlib.pyplot as plt
if fig is None:
fig = plt.gcf()
if ax is None:
ax = fig.add_subplot(1, 1, 1, projection=self.wcs)
kwargs['origin'] = kwargs.get('origin', 'lower')
kwargs['interpolation'] = kwargs.get('interpolation', 'None')
ne = self.data.shape[0]
if ne != 3:
raise ValueError("Energy axes must be length 3, but is {}".format(ne))
data_rgb = []
for idx in range(3):
data_rgb.append(self.data[idx, :, :])
ax.imshow(np.dstack(data_rgb), **kwargs)
try:
ax.coords['glon'].set_axislabel('Galactic Longitude')
ax.coords['glat'].set_axislabel('Galactic Latitude')
except KeyError:
ax.coords['ra'].set_axislabel('Right Ascension')
ax.coords['dec'].set_axislabel('Declination')
# without this the axis limits are changed when calling scatter
ax.autoscale(enable=False)
return ax
[docs] def sky_image_integral(self, emin, emax, nbins=10, per_decade=False, interpolation='linear'):
"""Integrate cube along the energy axes using the log-log trapezoidal rule.
Parameters
----------
emin : `~astropy.units.Quantity`
Integration range minimum.
emax : `~astropy.units.Quantity`
Integration range maximum.
nbins : int, optional
Number of grid points used for the integration.
per_decade : bool
Whether nbins is per decade.
interpolation : {None, 'linear', 'nearest'}
Interpolate data values between energies.
Returns
-------
image : `~gammapy.image.SkyImage`
Integral image.
"""
y, x = np.indices(self.data.shape[1:])
if interpolation:
energy = Energy.equal_log_spacing(emin, emax, nbins, per_decade=per_decade)
z = self.energy_axis.wcs_world2pix(energy).reshape(-1, 1, 1)
y = np.arange(self.data.shape[1])
x = np.arange(self.data.shape[2])
z, y, x = np.meshgrid(z, y, x, indexing='ij')
data = self._interpolate_data(z, y, x)
else:
zmin = np.rint(self.energy_axis.wcs_world2pix(emin)).astype('int')
zmax = np.rint(self.energy_axis.wcs_world2pix(emax)).astype('int')
energy = self.energies()[zmin:zmax]
data = self.data[zmin:zmax]
integral = _trapz_loglog(data, energy, axis=0)
name = 'integrated {}'.format(self.name)
return SkyImage(name=name, data=integral, wcs=self.wcs.celestial)
[docs] def reproject(self, reference, mode='interp', *args, **kwargs):
"""Reproject spatial dimensions onto a reference image.
Parameters
----------
reference : `~astropy.io.fits.Header`, `~gammapy.image.SkyImage` or `SkyCube`
Reference wcs specification to reproject the data on.
mode : {'interp', 'exact'}
Interpolation mode.
*args : list
Arguments passed to `~reproject.reproject_interp` or
`~reproject.reproject_exact`.
**kwargs : dict
Keyword arguments passed to `~reproject.reproject_interp` or
`~reproject.reproject_exact`.
Returns
-------
reprojected_cube : `SkyCube`
Cube spatially reprojected to the reference.
"""
if isinstance(reference, SkyCube):
reference = reference.sky_image_ref
out = []
for energy in self.energies():
image = self.sky_image(energy)
image_out = image.reproject(reference, mode=mode, *args, **kwargs)
out.append(image_out.data)
data = Quantity(np.stack(out, axis=0), self.data.unit)
wcs = image_out.wcs.copy()
return self.__class__(name=self.name, data=data, wcs=wcs, meta=self.meta,
energy_axis=self.energy_axis)
[docs] def convolve(self, kernels, **kwargs):
"""Convolve cube with a given set of kernels.
Parameters
----------
kernels : list or `~numpy.ndarray`
List of 2D convolution kernels or 3D array. The energy axis
must correspond to array axis=0.
Returns
-------
convolved : `SkyCube`
Convolved cube.
"""
data = []
if not len(kernels) == self.data.shape[0]:
raise ValueError('Number of kernels must match size of energy axis'
' of the cube.')
for idx, kernel in enumerate(kernels):
image = self.sky_image_idx(idx)
data.append(image.convolve(kernel, **kwargs).data)
convolved = u.Quantity(data)
wcs = self.wcs.deepcopy() if self.wcs else None
return self.__class__(name=self.name, data=convolved, wcs=wcs,
energy_axis=self.energy_axis)
[docs] def to_fits(self, format):
"""Write to FITS HDU list.
Parameters
----------
format : {'fermi-counts', 'fermi-background', 'fermi-exposure'}
Fits file format.
Returns
-------
hdu_list : `~astropy.io.fits.HDUList`
* hdu_list[0] : `~astropy.io.fits.PrimaryHDU`
Image array of data
* hdu_list[1] : `~astropy.io.fits.BinTableHDU`
Table of energies
"""
image_hdu = fits.PrimaryHDU(self.data.value, self.wcs.to_header())
image_hdu.header['SPECUNIT'] = '{0.unit:FITS}'.format(self.data)
if format == 'fermi-counts':
energies = self.energies(mode='edges')
# for BinTableHDU's the data must be added via a Table object
energy_table = Table()
energy_table['E_MIN'] = energies[:-1]
energy_table['E_MAX'] = energies[1:]
energy_table.meta['name'] = 'EBOUNDS'
energy_hdu = table_to_fits_table(energy_table)
elif format in ['fermi-exposure', 'fermi-background']:
# for BinTableHDU's the data must be added via a Table object
energy_table = Table()
energy_table['Energy'] = self.energies()
energy_table.meta['name'] = 'ENERGIES'
energy_hdu = table_to_fits_table(energy_table)
else:
raise ValueError('Not a valid cube fits format')
hdu_list = fits.HDUList([image_hdu, energy_hdu])
return hdu_list
[docs] def to_images(self):
"""Convert to `~gammapy.cube.SkyCubeImages`."""
from .images import SkyCubeImages
energies = self.energies(mode='center')
images = [self.sky_image(energy) for energy in energies]
return SkyCubeImages(self.name, images, self.wcs, energies)
[docs] def spectrum(self, region):
"""Extract spectrum in a given sky region.
Parameters
----------
region : `~regions.SkyRegion`
Sky region to extract the spectrum from.
Returns
-------
spectrum : `~astropy.table.Table`
Summed spectrum of pixels in the mask.
"""
spectrum = Table()
# store energy binning
energies = self.energies('edges')
e_ref = self.energies('center')
spectrum['e_min'] = energies[:-1]
spectrum['e_max'] = energies[1:]
spectrum['e_ref'] = e_ref
# mask region and sum
mask = self.region_mask(region)
value = (self.data * mask.data).sum(-1).sum(-1)
spectrum['value'] = value
return spectrum
[docs] def region_mask(self, region):
"""Create a boolean cube mask for a region.
The mask is:
- ``True`` for pixels inside the region
- ``False`` for pixels outside the region
Parameters
----------
region : `~regions.PixelRegion` or `~regions.SkyRegion`
Region in pixel or sky coordinates.
Returns
-------
mask : `SkyCube`
A boolean sky cube mask.
"""
mask = self.sky_image_ref.region_mask(region)
data = mask.data * np.ones(self.data.shape, dtype='bool') * u.Unit('')
wcs = self.wcs.deepcopy() if self.wcs else None
return self.__class__(name=self.name, data=data.astype('bool'), wcs=wcs,
energy_axis=self.energy_axis)
[docs] def write(self, filename, format='fermi-counts', **kwargs):
"""Write to FITS file.
Parameters
----------
filename : str
Filename
format : {'fermi-counts', 'fermi-background', 'fermi-exposure'}
Fits file format.
"""
filename = str(make_path(filename))
self.to_fits(format).writeto(filename, **kwargs)
def __str__(self):
ss = "Sky cube {} with shape={}".format(self.name, self.data.shape)
if self.data.unit is u.dimensionless_unscaled:
ss += ":\n"
else:
ss += " and unit={}:\n".format(self.data.unit)
ss += " n_lon: {:5d} type_lon: {:15s} unit_lon: {}\n".format(
self.data.shape[2], self.wcs.wcs.ctype[0], self.wcs.wcs.cunit[0])
ss += " n_lat: {:5d} type_lat: {:15s} unit_lat: {}\n".format(
self.data.shape[1], self.wcs.wcs.ctype[1], self.wcs.wcs.cunit[1])
ss += " n_energy: {:5d} unit_energy: {}\n".format(
self.data.shape[0], self.energy_axis._eunit)
return ss
[docs] def info(self):
"""Print summary info about the cube."""
print(repr(self))
@staticmethod
[docs] def assert_allclose(cube1, cube2):
from ..utils.testing import assert_wcs_allclose
assert cube1.name == cube2.name
assert_allclose(cube1.data, cube2.data)
assert_wcs_allclose(cube1.wcs, cube2.wcs)