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, meta=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.
metaMapDatasetMetaData: Associated meta data container

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.
`gti`
`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.
`meta`
`meta_table`
`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`()	Not implemented for MapDatasetOnOff.
`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, checksum])	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: Dictionary of map geometries involved in the dataset.

gti = None#

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.

meta#

meta_table = None#

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, optional: Name of the copied dataset. Default is None.

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, optional: True energy axis used for IRF maps. Default is None.
migra_axisMapAxis, optional: 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, optional: Rad axis for the PSF map. Default is None.
binsz_irffloat: IRF Map pixel size in degrees. Default is BINSZ_IRF_DEFAULT.
reference_timeTime: The reference time to use in GTI definition. Default is “2000-01-01”.
namestr, optional: Name of the returned dataset. Default is None.
meta_tableTable, optional: Table listing information on observations used to create the dataset. One line per observation for stacked datasets. Default is None.
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. Default is “trim”.
namestr, optional: Name of the new dataset. Default is None.

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, optional: Which non-spatial axis to downsample. By default, only spatial axes are downsampled. Default is None.
namestr, optional: Name of the downsampled dataset. Default is None.

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. Default is “random-seed”.

classmethod from_dict(data, lazy=False, cache=True)#: Create from dicts and models list generated from YAML serialization.

classmethod from_geoms(geom, geom_exposure=None, 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, optional: Geometry for the exposure map. Default is None.
geom_psfgammapy.maps.WcsGeom, optional: Geometry for the PSF map. Default is None.
geom_edispgammapy.maps.WcsGeom, optional: Geometry for the energy dispersion kernel map. If geom_edisp has a migra axis, this will create an EDispMap instead. Default is None.
reference_timeTime: The reference time to use in GTI definition. Default is “2000-01-01”.
namestr, optional: Name of the returned dataset. Default is None.
**kwargsdict, optional: Keyword arguments to be passed.

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, optional: Name of the new dataset. Default is None.
format{“gadf”}: Format the hdulist is given in. Default is “gadf”.

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, optional: 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. Default is None.
namestr, optional: Name of the returned dataset. Default is None.

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. Default is True.

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_nameslist of str: List of name of SkyModel for which to compute the npred. If none, all the SkyModel predicted counts are computed.
stackbool: Whether to stack the npred maps upon each other.

Returns

npred_siggammapy.maps.Map: Map of the predicted signal counts.

pad()[source]#: Not implemented for MapDatasetOnOff.

peek(figsize=(12, 8))#

Quick-look summary plots.

Parameters

figsizetuple: Size of the figure. Default is (12, 10).

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, optional: Axes to plot spatial residuals on. Default is None.
ax_spectralAxes, optional: Axes to plot spectral residuals on. Default is None.
kwargs_spatialdict, optional: Keyword arguments passed to plot_residuals_spatial. Default is None.
kwargs_spectraldict, optional: Keyword arguments passed to plot_residuals_spectral. The region should be passed as a dictionary key. Default is None.

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"}
>>> 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, optional: Axes to plot on. Default is None.
method{“diff”, “diff/model”, “diff/sqrt(model)”}: Normalization used to compute the residuals, see MapDataset.residuals. Default is “diff”.
smooth_kernel{“gauss”, “box”}: Kernel shape. Default is “gauss”.
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. Default is “0.1 deg”.
**kwargsdict, optional: 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, optional: Axes to plot on. Default is None.
method{“diff”, “diff/sqrt(model)”}: Normalization used to compute the residuals, see SpectrumDataset.residuals. Default is “diff”.
regionSkyRegion (required): Target sky region. Default is None.
**kwargsdict, optional: 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', checksum=False)#

Read a dataset from file.

Parameters

filenamestr: Filename to read from.
namestr, optional: Name of the new dataset. Default is None.
lazybool: Whether to lazy load data into memory. Default is False.
cachebool: Whether to cache the data after loading. Default is True.
format{“gadf”}: Format of the dataset file. Default is “gadf”.
checksumbool: If True checks both DATASUM and CHECKSUM cards in the file headers. Default is False.

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.
namestr, optional: Name of the new dataset. Default is None.

Returns

datasetSpectrumDataset: 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).

Default is “diff”.

**kwargsdict, optional

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, optional: Energy bounds to compute the flux point for. Default is None.
namestr, optional: Name of the sliced dataset. Default is None.

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: Dictionary 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, optional: Name of the sliced dataset. Default is None.

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_numbool: Non-finite values are replaced by zero if True. Default is True.

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, optional: Name of the new dataset. Default is None.

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

namestr, optional: Name of the new dataset. Default is None.

Returns

datasetMapDataset: Map dataset with cash statistics.

to_masked(name=None, nan_to_num=True)#

Return masked dataset.

Parameters

namestr, optional: Name of the masked dataset. Default is None.
nan_to_numbool: Non-finite values are replaced by zero if True. Default is True.

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, optional: Name of the new dataset. Default is None.

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. Default is False.
namestr, optional: Name of the new dataset. Default is None.

Returns

datasetSpectrumDatasetOnOff: The resulting reduced dataset.

write(filename, overwrite=False, checksum=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, optional: Overwrite existing file. Default is False.
checksumbool: When True adds both DATASUM and CHECKSUM cards to the headers written to the file. Default is False.