MapDatasetOnOff#

class gammapy.datasets.MapDatasetOnOff(models=None, counts=None, counts_off=None, acceptance=None, acceptance_off=None, exposure=None, mask_fit=None, psf=None, edisp=None, name=None, mask_safe=None, gti=None, meta_table=None)[source]#

Bases: gammapy.datasets.map.MapDataset

Map dataset for on-off likelihood fitting.

It bundles together the binned on and off counts, the binned IRFs as well as the on and off acceptances.

A safe mask and a fit mask can be added to exclude bins during the analysis.

It uses the Wstat statistic (see wstat), therefore no background model is needed.

For more information see Datasets (DL4).

Parameters
modelsModels

Source sky models.

countsWcsNDMap

Counts cube

counts_offWcsNDMap

Ring-convolved counts cube

acceptanceWcsNDMap

Acceptance from the IRFs

acceptance_offWcsNDMap

Acceptance off

exposureWcsNDMap

Exposure cube

mask_fitWcsNDMap

Mask to apply to the likelihood for fitting.

psfPSFKernel

PSF kernel

edispEDispKernel

Energy dispersion

mask_safeWcsNDMap

Mask defining the safe data range.

gtiGTI

GTI of the observation or union of GTI if it is a stacked observation

meta_tableTable

Table listing information on observations used to create the dataset. One line per observation for stacked datasets.

namestr

Name of the dataset.

See also

MapDataset, SpectrumDataset, FluxPointsDataset

Attributes Summary

alpha

Exposure ratio between signal and background regions

background

Computed as alpha * n_off

background_model

counts

A lazy FITS data descriptor.

data_shape

Shape of the counts or background data (tuple).

edisp

A lazy FITS data descriptor.

energy_range

Energy range maps defined by the mask_safe and mask_fit.

energy_range_fit

Energy range maps defined by the mask_fit only.

energy_range_safe

Energy range maps defined by the mask_safe only.

energy_range_total

Largest energy range among all pixels, defined by mask_safe and mask_fit.

evaluators

Model evaluators.

excess

Observed excess: counts-background.

exposure

A lazy FITS data descriptor.

geoms

Map geometries.

mask

Combined fit and safe mask.

mask_fit

A lazy FITS data descriptor.

mask_fit_image

Reduced fit mask.

mask_image

Reduced mask.

mask_safe

A lazy FITS data descriptor.

mask_safe_edisp

Safe mask for edisp maps.

mask_safe_image

Reduced safe mask.

mask_safe_psf

Safe mask for psf maps.

models

Models set on the dataset (Models).

name

psf

A lazy FITS data descriptor.

stat_type

tag

Methods Summary

copy([name])

A deep copy.

create(geom[, energy_axis_true, migra_axis, ...])

Create a MapDataset object with zero filled maps.

cutout(position, width[, mode, name])

Cutout map dataset.

downsample(factor[, axis_name, name])

Downsample map dataset.

fake(npred_background[, random_state])

Simulate fake counts (on and off) for the current model and reduced IRFs.

from_dict(data[, lazy, cache])

Create from dicts and models list generated from YAML serialization.

from_geoms(geom, geom_exposure[, geom_psf, ...])

Create an empty MapDatasetOnOff object according to the specified geometries.

from_hdulist(hdulist[, name, format])

Create map dataset from list of HDUs.

from_map_dataset(dataset, acceptance, ...[, ...])

Create on off dataset from a map dataset.

info_dict([in_safe_data_range])

Basic info dict with summary statistics.

npred()

Total predicted source and background counts.

npred_background()

Predicted background counts estimated from the marginalized likelihood estimate.

npred_off()

Predicted counts in the off region; mu_bkg/alpha

npred_signal([model_names, stack])

Model predicted signal counts.

pad()

Pad the spatial dimensions of the dataset.

peek([figsize])

Quick-look summary plots.

plot_residuals([ax_spatial, ax_spectral, ...])

Plot spatial and spectral residuals in two panels.

plot_residuals_spatial([ax, method, ...])

Plot spatial residuals.

plot_residuals_spectral([ax, method, region])

Plot spectral residuals.

read(filename[, name, lazy, cache, format])

Read a dataset from file.

resample_energy_axis(energy_axis[, name])

Resample MapDatasetOnOff over reconstructed energy edges.

reset_data_cache()

Reset data cache to free memory space

residuals([method])

Compute residuals map.

slice_by_energy([energy_min, energy_max, name])

Select and slice datasets in energy range

slice_by_idx(slices[, name])

Slice sub dataset.

stack(other[, nan_to_num])

Stack another dataset in place.

stat_array()

Statistic function value per bin given the current model parameters

stat_sum()

Total statistic function value given the current model parameters.

to_dict()

Convert to dict for YAML serialization.

to_hdulist()

Convert map dataset to list of HDUs.

to_image([name])

Create images by summing over the reconstructed energy axis.

to_map_dataset([name])

Convert a MapDatasetOnOff to a MapDataset.

to_masked([name, nan_to_num])

Return masked dataset.

to_region_map_dataset(region[, name])

Integrate the map dataset in a given region.

to_spectrum_dataset(on_region[, ...])

Return a ~gammapy.datasets.SpectrumDatasetOnOff from on_region.

write(filename[, overwrite])

Write Dataset to file.

Attributes Documentation

alpha#

Exposure ratio between signal and background regions

See WStat : Poisson data with background measurement

Returns
alphaMap

Alpha map

background#

Computed as alpha * n_off

See WStat : Poisson data with background measurement

Returns
backgroundMap

Background map

background_model#
counts#

A lazy FITS data descriptor.

Parameters
cachebool

Whether to cache the data.

data_shape#

Shape of the counts or background data (tuple).

edisp#

A lazy FITS data descriptor.

Parameters
cachebool

Whether to cache the data.

energy_range#

Energy range maps defined by the mask_safe and mask_fit.

energy_range_fit#

Energy range maps defined by the mask_fit only.

energy_range_safe#

Energy range maps defined by the mask_safe only.

energy_range_total#

Largest energy range among all pixels, defined by mask_safe and mask_fit.

evaluators#

Model evaluators.

excess#

Observed excess: counts-background.

exposure#

A lazy FITS data descriptor.

Parameters
cachebool

Whether to cache the data.

geoms#

Map geometries.

Returns
geomsdict

Dict of map geometries involved in the dataset.

mask#

Combined fit and safe mask.

mask_fit#

A lazy FITS data descriptor.

Parameters
cachebool

Whether to cache the data.

mask_fit_image#

Reduced fit mask.

mask_image#

Reduced mask.

mask_safe#

A lazy FITS data descriptor.

Parameters
cachebool

Whether to cache the data.

mask_safe_edisp#

Safe mask for edisp maps.

mask_safe_image#

Reduced safe mask.

mask_safe_psf#

Safe mask for psf maps.

models#

Models set on the dataset (Models).

name#
psf#

A lazy FITS data descriptor.

Parameters
cachebool

Whether to cache the data.

stat_type = 'wstat'#
tag = 'MapDatasetOnOff'#

Methods Documentation

copy(name=None)#

A deep copy.

Parameters
namestr

Name of the copied dataset

Returns
datasetDataset

Copied datasets.

classmethod create(geom, energy_axis_true=None, migra_axis=None, rad_axis=None, binsz_irf=<Quantity 0.2 deg>, reference_time='2000-01-01', name=None, meta_table=None, reco_psf=False, **kwargs)#

Create a MapDataset object with zero filled maps.

Parameters
geomWcsGeom

Reference target geometry in reco energy, used for counts and background maps

energy_axis_trueMapAxis

True energy axis used for IRF maps

migra_axisMapAxis

If set, this provides the migration axis for the energy dispersion map. If not set, an EDispKernelMap is produced instead. Default is None

rad_axisMapAxis

Rad axis for the psf map

binsz_irffloat

IRF Map pixel size in degrees.

reference_timeTime

the reference time to use in GTI definition

namestr

Name of the returned dataset.

meta_tableTable

Table listing information on observations used to create the dataset. One line per observation for stacked datasets.

reco_psfbool

Use reconstructed energy for the PSF geometry. Default is False

Returns
empty_mapsMapDataset

A MapDataset containing zero filled maps

Examples

>>> from gammapy.datasets import MapDataset
>>> from gammapy.maps import WcsGeom, MapAxis

>>> energy_axis = MapAxis.from_energy_bounds(1.0, 10.0, 4, unit="TeV")
>>> energy_axis_true = MapAxis.from_energy_bounds(
            0.5, 20, 10, unit="TeV", name="energy_true"
        )
>>> geom = WcsGeom.create(
            skydir=(83.633, 22.014),
            binsz=0.02, width=(2, 2),
            frame="icrs",
            proj="CAR",
            axes=[energy_axis]
        )
>>> empty = MapDataset.create(geom=geom, energy_axis_true=energy_axis_true, name="empty")
cutout(position, width, mode='trim', name=None)[source]#

Cutout map dataset.

Parameters
positionSkyCoord

Center position of the cutout region.

widthtuple of Angle

Angular sizes of the region in (lon, lat) in that specific order. If only one value is passed, a square region is extracted.

mode{‘trim’, ‘partial’, ‘strict’}

Mode option for Cutout2D, for details see Cutout2D.

namestr

Name of the new dataset.

Returns
cutoutMapDatasetOnOff

Cutout map dataset.

downsample(factor, axis_name=None, name=None)[source]#

Downsample map dataset.

The PSFMap and EDispKernelMap are not downsampled, except if a corresponding axis is given.

Parameters
factorint

Downsampling factor.

axis_namestr

Which non-spatial axis to downsample. By default, only spatial axes are downsampled.

namestr

Name of the downsampled dataset.

Returns
datasetMapDatasetOnOff

Downsampled map dataset.

fake(npred_background, random_state='random-seed')[source]#

Simulate fake counts (on and off) for the current model and reduced IRFs.

This method overwrites the counts defined on the dataset object.

Parameters
npred_backgroundMap

Expected number of background counts in the on region

random_state{int, ‘random-seed’, ‘global-rng’, RandomState}

Defines random number generator initialisation. Passed to get_random_state.

classmethod from_dict(data, lazy=False, cache=True)#

Create from dicts and models list generated from YAML serialization.

classmethod from_geoms(geom, geom_exposure, geom_psf=None, geom_edisp=None, reference_time='2000-01-01', name=None, **kwargs)[source]#

Create an empty MapDatasetOnOff object according to the specified geometries.

Parameters
geomgammapy.maps.WcsGeom

geometry for the counts, counts_off, acceptance and acceptance_off maps

geom_exposuregammapy.maps.WcsGeom

geometry for the exposure map

geom_psfgammapy.maps.WcsGeom

geometry for the psf map

geom_edispgammapy.maps.WcsGeom

geometry for the energy dispersion kernel map. If geom_edisp has a migra axis, this will create an EDispMap instead.

reference_timeTime

the reference time to use in GTI definition

namestr

Name of the returned dataset.

Returns
empty_mapsMapDatasetOnOff

A MapDatasetOnOff containing zero filled maps

classmethod from_hdulist(hdulist, name=None, format='gadf')[source]#

Create map dataset from list of HDUs.

Parameters
hdulistHDUList

List of HDUs.

namestr

Name of the new dataset.

format{“gadf”}

Format the hdulist is given in.

Returns
datasetMapDatasetOnOff

Map dataset.

classmethod from_map_dataset(dataset, acceptance, acceptance_off, counts_off=None, name=None)[source]#

Create on off dataset from a map dataset.

Parameters
datasetMapDataset

Spectrum dataset defining counts, edisp, aeff, livetime etc.

acceptanceMap

Relative background efficiency in the on region.

acceptance_offMap

Relative background efficiency in the off region.

counts_offMap

Off counts map . If the dataset provides a background model, and no off counts are defined. The off counts are deferred from counts_off / alpha.

namestr

Name of the returned dataset.

Returns
datasetMapDatasetOnOff

Map dataset on off.

info_dict(in_safe_data_range=True)[source]#

Basic info dict with summary statistics.

If a region is passed, then a spectrum dataset is extracted, and the corresponding info returned.

Parameters
in_safe_data_rangebool

Whether to sum only in the safe energy range

Returns
info_dictdict

Dictionary with summary info.

npred()#

Total predicted source and background counts.

Returns
npredMap

Total predicted counts

npred_background()[source]#

Predicted background counts estimated from the marginalized likelihood estimate.

See WStat : Poisson data with background measurement

Returns
npred_backgroundMap

Predicted background counts

npred_off()[source]#

Predicted counts in the off region; mu_bkg/alpha

See WStat : Poisson data with background measurement

Returns
npred_offMap

Predicted off counts

npred_signal(model_names=None, stack=True)#

Model predicted signal counts.

If a list of model name is passed, predicted counts from these components are returned. If stack is set to True, a map of the sum of all the predicted counts is returned. If stack is set to False, a map with an additional axis representing the models is returned.

Parameters
model_names: list of str

List of name of SkyModel for which to compute the npred. If none, all the SkyModel predicted counts are computed

stack: bool

Whether to stack the npred maps upon each other.

Returns
npred_sig: gammapy.maps.Map

Map of the predicted signal counts

pad()[source]#

Pad the spatial dimensions of the dataset.

The padding only applies to counts, masks, background and exposure.

Counts, background and masks are padded with zeros, exposure is padded with edge value.

Parameters
pad_width{sequence, array_like, int}

Number of pixels padded to the edges of each axis.

namestr

Name of the padded dataset.

Returns
datasetMapDataset

Padded map dataset.

peek(figsize=(12, 10))#

Quick-look summary plots.

Parameters
figsizetuple

Size of the figure.

plot_residuals(ax_spatial=None, ax_spectral=None, kwargs_spatial=None, kwargs_spectral=None)#

Plot spatial and spectral residuals in two panels.

Calls plot_residuals_spatial and plot_residuals_spectral. The spectral residuals are extracted from the provided region, and the normalization used for its computation can be controlled using the method parameter. The region outline is overlaid on the residuals map. If no region is passed, the residuals are computed for the entire map

Parameters
ax_spatialWCSAxes

Axes to plot spatial residuals on.

ax_spectralAxes

Axes to plot spectral residuals on.

kwargs_spatialdict

Keyword arguments passed to plot_residuals_spatial.

kwargs_spectraldict

Keyword arguments passed to plot_residuals_spectral. The region should be passed as a dictionary key

Returns
ax_spatial, ax_spectralWCSAxes, Axes

Spatial and spectral residuals plots.

Examples

>>> from regions import CircleSkyRegion
>>> from astropy.coordinates import SkyCoord
>>> import astropy.units as u
>>> from gammapy.datasets import MapDataset
>>> dataset = MapDataset.read("$GAMMAPY_DATA/cta-1dc-gc/cta-1dc-gc.fits.gz")
>>> reg = CircleSkyRegion(SkyCoord(0,0, unit="deg", frame="galactic"), radius=1.0 * u.deg)
>>> kwargs_spatial = {"cmap": "RdBu_r", "vmin":-5, "vmax":5, "add_cbar": True}
>>> kwargs_spectral = {"region":reg, "markerfacecolor": "blue", "markersize": 8, "marker": "s"}  # noqa: E501
>>> dataset.plot_residuals(kwargs_spatial=kwargs_spatial, kwargs_spectral=kwargs_spectral)
plot_residuals_spatial(ax=None, method='diff', smooth_kernel='gauss', smooth_radius='0.1 deg', **kwargs)#

Plot spatial residuals.

The normalization used for the residuals computation can be controlled using the method parameter.

Parameters
axWCSAxes

Axes to plot on.

method{“diff”, “diff/model”, “diff/sqrt(model)”}

Normalization used to compute the residuals, see MapDataset.residuals.

smooth_kernel{“gauss”, “box”}

Kernel shape.

smooth_radius: `~astropy.units.Quantity`, str or float

Smoothing width given as quantity or float. If a float is given, it is interpreted as smoothing width in pixels.

**kwargsdict

Keyword arguments passed to imshow.

Returns
axWCSAxes

WCSAxes object.

Examples

>>> from gammapy.datasets import MapDataset
>>> dataset = MapDataset.read("$GAMMAPY_DATA/cta-1dc-gc/cta-1dc-gc.fits.gz")
>>> kwargs = {"cmap": "RdBu_r", "vmin":-5, "vmax":5, "add_cbar": True}
>>> dataset.plot_residuals_spatial(method="diff/sqrt(model)", **kwargs)
plot_residuals_spectral(ax=None, method='diff', region=None, **kwargs)#

Plot spectral residuals.

The residuals are extracted from the provided region, and the normalization used for its computation can be controlled using the method parameter.

The error bars are computed using the uncertainty on the excess with a symmetric assumption.

Parameters
axAxes

Axes to plot on.

method{“diff”, “diff/sqrt(model)”}

Normalization used to compute the residuals, see SpectrumDataset.residuals.

region: `~regions.SkyRegion` (required)

Target sky region.

**kwargsdict

Keyword arguments passed to errorbar.

Returns
axAxes

Axes object.

Examples

>>> from gammapy.datasets import MapDataset
>>> dataset = MapDataset.read("$GAMMAPY_DATA/cta-1dc-gc/cta-1dc-gc.fits.gz")
>>> kwargs = {"markerfacecolor": "blue", "markersize":8, "marker":'s'}
>>> dataset.plot_residuals_spectral(method="diff/sqrt(model)", **kwargs)
classmethod read(filename, name=None, lazy=False, cache=True, format='gadf')#

Read a dataset from file.

Parameters
filenamestr

Filename to read from.

namestr

Name of the new dataset.

lazybool

Whether to lazy load data into memory

cachebool

Whether to cache the data after loading.

format{“gadf”}

Format of the dataset file.

Returns
datasetMapDataset

Map dataset.

resample_energy_axis(energy_axis, name=None)[source]#

Resample MapDatasetOnOff over reconstructed energy edges.

Counts are summed taking into account safe mask.

Parameters
energy_axisMapAxis

New reco energy axis.

name: str

Name of the new dataset.

Returns
dataset: SpectrumDataset

Resampled spectrum dataset .

reset_data_cache()#

Reset data cache to free memory space

residuals(method='diff', **kwargs)#

Compute residuals map.

Parameters
method: {“diff”, “diff/model”, “diff/sqrt(model)”}
Method used to compute the residuals. Available options are:

  • “diff” (default): data - model

  • “diff/model”: (data - model) / model

  • “diff/sqrt(model)”: (data - model) / sqrt(model)

**kwargsdict

Keyword arguments forwarded to Map.smooth()

Returns
residualsgammapy.maps.Map

Residual map.

slice_by_energy(energy_min=None, energy_max=None, name=None)#

Select and slice datasets in energy range

Parameters
energy_min, energy_maxQuantity

Energy bounds to compute the flux point for.

namestr

Name of the sliced dataset.

Returns
datasetMapDataset

Sliced Dataset

Examples

>>> from gammapy.datasets import MapDataset
>>> dataset = MapDataset.read("$GAMMAPY_DATA/cta-1dc-gc/cta-1dc-gc.fits.gz")
>>> sliced = dataset.slice_by_energy(energy_min="1 TeV", energy_max="5 TeV")
>>> sliced.data_shape
(3, 240, 320)
slice_by_idx(slices, name=None)[source]#

Slice sub dataset.

The slicing only applies to the maps that define the corresponding axes.

Parameters
slicesdict

Dict of axes names and integers or slice object pairs. Contains one element for each non-spatial dimension. For integer indexing the corresponding axes is dropped from the map. Axes not specified in the dict are kept unchanged.

namestr

Name of the sliced dataset.

Returns
map_outMap

Sliced map object.

stack(other, nan_to_num=True)[source]#

Stack another dataset in place.

The acceptance of the stacked dataset is normalized to 1, and the stacked acceptance_off is scaled so that:

\[\alpha_\text{stacked} = \frac{1}{a_\text{off}} = \frac{\alpha_1\text{OFF}_1 + \alpha_2\text{OFF}_2}{\text{OFF}_1 + OFF_2}\]
Parameters
otherMapDatasetOnOff

Other dataset

nan_to_num: bool

Non-finite values are replaced by zero if True (default).

stat_array()[source]#

Statistic function value per bin given the current model parameters

stat_sum()[source]#

Total statistic function value given the current model parameters.

If the off counts are passed as None and the elements of the safe mask are False, zero will be returned. Otherwise, the stat sum will be calculated and returned.

to_dict()#

Convert to dict for YAML serialization.

to_hdulist()[source]#

Convert map dataset to list of HDUs.

Returns
hdulistHDUList

Map dataset list of HDUs.

to_image(name=None)#

Create images by summing over the reconstructed energy axis.

Parameters
namestr

Name of the new dataset.

Returns
datasetMapDataset or SpectrumDataset

Dataset integrated over non-spatial axes.

to_map_dataset(name=None)[source]#

Convert a MapDatasetOnOff to a MapDataset.

The background model template is taken as alpha * counts_off.

Parameters
name: str

Name of the new dataset

Returns
dataset: MapDataset

Map dataset with cash statistics

to_masked(name=None, nan_to_num=True)#

Return masked dataset.

Parameters
namestr

Name of the masked dataset.

nan_to_num: bool

Non-finite values are replaced by zero if True (default).

Returns
datasetMapDataset or SpectrumDataset

Masked dataset

to_region_map_dataset(region, name=None)#

Integrate the map dataset in a given region.

Counts and background of the dataset are integrated in the given region, taking the safe mask into account. The exposure is averaged in the region again taking the safe mask into account. The PSF and energy dispersion kernel are taken at the center of the region.

Parameters
regionSkyRegion

Region from which to extract the spectrum

namestr

Name of the new dataset.

Returns
datasetMapDataset

the resulting reduced dataset

to_spectrum_dataset(on_region, containment_correction=False, name=None)[source]#

Return a ~gammapy.datasets.SpectrumDatasetOnOff from on_region.

Counts and OFF counts are summed in the on_region.

Acceptance is the average of all acceptances while acceptance OFF is taken such that number of excess is preserved in the on_region.

Effective area is taken from the average exposure.

The energy dispersion kernel is obtained at the on_region center. Only regions with centers are supported.

The models are not exported to the ~gammapy.dataset.SpectrumDatasetOnOff. It must be set after the dataset extraction.

Parameters
on_regionSkyRegion

the input ON region on which to extract the spectrum

containment_correctionbool

Apply containment correction for point sources and circular on regions

namestr

Name of the new dataset.

Returns
datasetSpectrumDatasetOnOff

the resulting reduced dataset

write(filename, overwrite=False)#

Write Dataset to file.

A MapDataset is serialised using the GADF format with a WCS geometry. A SpectrumDataset uses the same format, with a RegionGeom.

Parameters
filenamestr

Filename to write to.

overwritebool

Overwrite file if it exists.