Background3D

class gammapy.irf.Background3D(axes, data=0, unit='', is_pointlike=False, fov_alignment=FoVAlignment.RADEC, meta=None, interp_kwargs=None)

Bases: gammapy.irf.background.BackgroundIRF

Background 3D.

Data format specification: BKG_3D

Parameters

axeslist of MapAxis or MapAxes object

Required data axes: [“energy”, “fov_lon”, “fov_lat”] in the given order.

datandarray

Data array.

unitstr or Unit

Data unit usually s^-1 MeV^-1 sr^-1

fov_alignment: `~gammapy.irf.FoVAlignment`

The orientation of the field of view coordinate system.

metadict

Meta data

Examples

Here’s an example you can use to learn about this class:

>>> from gammapy.irf import Background3D
>>> filename = '$GAMMAPY_DATA/cta-1dc/caldb/data/cta/1dc/bcf/South_z20_50h/irf_file.fits'
>>> bkg_3d = Background3D.read(filename, hdu='BACKGROUND')
>>> print(bkg_3d)
Background3D
------------

  axes  : ['energy', 'fov_lon', 'fov_lat']
  shape : (21, 36, 36)
  ndim  : 3
  unit  : 1 / (MeV s sr)
  dtype : >f4

Attributes Summary

axes	MapAxes
data
default_interp_kwargs	Default Interpolation kwargs to extrapolate.
default_unit
fov_alignment	Alignment of the field of view coordinate axes, see FoVAlignment
has_offset_axis	Whether the IRF explicitly depends on offset
is_pointlike	Whether the IRF is pointlike of full containment.
quantity	Quantity
required_axes
tag
unit	Map unit (Unit)

Methods Summary

cumsum(axis_name)	Compute cumsum along a given axis
evaluate([method])	Evaluate IRF
from_hdulist(hdulist[, hdu, format])	Create from HDUList.
from_table(table[, format])	Read from Table.
integral(axis_name, **kwargs)	Compute integral along a given axis
integrate_log_log(axis_name, **kwargs)	Integrate along a given axis.
interp_missing_data(axis_name)	Interpolate missing data along a given axis
is_allclose(other[, rtol_axes, atol_axes])	Compare two data IRFs for equivalency
normalize(axis_name)	Normalise data in place along a given axis.
pad(pad_width, axis_name, **kwargs)	Pad irf along a given axis.
peek([figsize])	Quick-look summary plots.
plot_at_energy([energy, add_cbar, ncols, ...])	Plot the background rate in Field of view coordinates at a given energy.
read(filename[, hdu, format])	Read from file.
slice_by_idx(slices)	Slice sub IRF from IRF object.
to_2d()	Convert to Background2D.
to_hdulist([format])
to_table([format])	Convert to table
to_table_hdu([format])	Convert to BinTableHDU.
to_unit(unit)	Convert irf to different unit
write(filename, *args, **kwargs)	Write IRF to fits.

Attributes Documentation

axes

MapAxes

data

default_interp_kwargs = {'bounds_error': False, 'fill_value': 0.0, 'values_scale': 'log'}

Default Interpolation kwargs to extrapolate.

default_unit = Unit("1 / (MeV s sr)")

fov_alignment

Alignment of the field of view coordinate axes, see FoVAlignment

has_offset_axis

Whether the IRF explicitly depends on offset

is_pointlike

Whether the IRF is pointlike of full containment.

quantity

Quantity

required_axes = ['energy', 'fov_lon', 'fov_lat']

tag = 'bkg_3d'

unit

Map unit (Unit)

Methods Documentation

cumsum(axis_name)

Compute cumsum along a given axis

Parameters

axis_namestr

Along which axis to integrate.

Returns

irfIRF

Cumsum IRF

evaluate(method=None, **kwargs)

Evaluate IRF

Parameters

**kwargsdict

Coordinates at which to evaluate the IRF

methodstr {‘linear’, ‘nearest’}, optional

Interpolation method

Returns

arrayQuantity

Interpolated values

classmethod from_hdulist(hdulist, hdu=None, format='gadf-dl3')

Create from HDUList.

Parameters

hdulistHDUList

HDU list

hdustr

HDU name

format{“gadf-dl3”}

Format specification

Returns

irfIRF

IRF class

classmethod from_table(table, format='gadf-dl3')

Read from Table.

Parameters

tableTable

Table with background data

format{“gadf-dl3”}

Format specification

Returns

bkgBackground2D or Background2D

Background IRF class.

integral(axis_name, **kwargs)

Compute integral along a given axis

This method uses interpolation of the cumulative sum.

Parameters

axis_namestr

Along which axis to integrate.

**kwargsdict

Coordinates at which to evaluate the IRF

Returns

arrayQuantity

Returns 2D array with axes offset

integrate_log_log(axis_name, **kwargs)

Integrate along a given axis.

This method uses log-log trapezoidal integration.

Parameters

axis_namestr

Along which axis to integrate.

**kwargsdict

Coordinates at which to evaluate the IRF

Returns

arrayQuantity

Returns 2D array with axes offset

interp_missing_data(axis_name)

Interpolate missing data along a given axis

is_allclose(other, rtol_axes=0.001, atol_axes=1e-06, **kwargs)

Compare two data IRFs for equivalency

Parameters

othergammapy.irfs.IRF

The irf to compare against

rtol_axesfloat

Relative tolerance for the axes comparison.

atol_axesfloat

Relative tolerance for the axes comparison.

**kwargsdict

keywords passed to numpy.allclose

Returns

is_allclosebool

Whether the IRF is all close.

normalize(axis_name)

Normalise data in place along a given axis.

Parameters

axis_namestr

Along which axis to normalize.

pad(pad_width, axis_name, **kwargs)

Pad irf along a given axis.

Parameters

pad_width{sequence, array_like, int}

Number of pixels padded to the edges of each axis.

axis_namestr

Which axis to downsample. By default spatial axes are padded.

**kwargsdict

Keyword argument forwarded to pad

Returns

irfIRF

Padded irf

peek(figsize=(10, 8))

Quick-look summary plots.

Parameters

figsizetuple

Size of the figure.

plot_at_energy(energy=None, add_cbar=True, ncols=3, figsize=None, **kwargs)

Plot the background rate in Field of view coordinates at a given energy.

Parameters

energyQuantity

list of Energy

add_cbarbool

Add color bar?

ncolsint

Number of columns to plot

figsizetuple

Figure size

**kwargsdict

Keyword arguments passed to pcolormesh.

classmethod read(filename, hdu=None, format='gadf-dl3')

Read from file.

Parameters

filenamestr or Path

Filename

hdustr

HDU name

format{“gadf-dl3”}

Format specification

Returns

irfIRF

IRF class

slice_by_idx(slices)

Slice sub IRF from IRF object.

Parameters

slicesdict

Dict of axes names and slice object pairs. Contains one element for each non-spatial dimension. Axes not specified in the dict are kept unchanged.

Returns

slicedIRF

Sliced IRF object.

to_2d()

Convert to Background2D.

This takes the values at Y = 0 and X >= 0.

to_hdulist(format='gadf-dl3')

to_table(format='gadf-dl3')

Convert to table

Parameters

format{“gadf-dl3”}

Format specification

Returns

tableTable

IRF data table

to_table_hdu(format='gadf-dl3')

Convert to BinTableHDU.

Parameters

format{“gadf-dl3”}

Format specification

Returns

hduBinTableHDU

IRF data table hdu

to_unit(unit)

Convert irf to different unit

Parameters

unitUnit or str

New unit

Returns

irfIRF

IRF with new unit and converted data

write(filename, *args, **kwargs)

Write IRF to fits.

Calls writeto, forwarding all arguments.