FluxPointsDataset

class gammapy.datasets.FluxPointsDataset(models, data, mask_fit=None, mask_safe=None, name=None)

Bases: gammapy.datasets.Dataset

Fit a set of flux points with a parametric model.

Parameters

modelsModels

Models (only spectral part needs to be set)

dataFluxPoints

Flux points.

mask_fitnumpy.ndarray

Mask to apply for fitting

mask_safenumpy.ndarray

Mask defining the safe data range.

Examples

Load flux points from file and fit with a power-law model:

from gammapy.modeling import Fit
from gammapy.modeling.models import PowerLawSpectralModel, SkyModel
from gammapy.estimators import FluxPoints
from gammapy.datasets import FluxPointsDataset

filename = "$GAMMAPY_DATA/tests/spectrum/flux_points/diff_flux_points.fits"
flux_points = FluxPoints.read(filename)

model = SkyModel(spectral_model=PowerLawSpectralModel())

dataset = FluxPointsDataset(model, flux_points)
fit = Fit([dataset])
result = fit.run()
print(result)
print(result.parameters.to_table())

Note: In order to reproduce the example you need the tests datasets folder. You may download it with the command gammapy download datasets --tests --out $GAMMAPY_DATA

Attributes Summary

mask	Combined fit and safe mask
models
name
stat_type
tag

Methods Summary

copy(self[, name])	A deep copy.
data_shape(self)	Shape of the flux points data (tuple).
flux_pred(self)	Compute predicted flux.
from_dict(data, models)	Create flux point dataset from dict.
peek(self[, method])	Plot flux points, best fit model and residuals.
plot_residuals(self[, ax, method])	Plot flux point residuals.
plot_spectrum(self[, ax, fp_kwargs, …])	Plot spectrum including flux points and model.
residuals(self[, method])	Compute the flux point residuals ().
stat_array(self)	Fit statistic array.
stat_sum(self)	Total statistic given the current model parameters.
to_dict(self[, filename])	Convert to dict for YAML serialization.
write(self, filename[, overwrite])	Write flux point dataset to file.

Attributes Documentation

mask

Combined fit and safe mask

models

name

stat_type = 'chi2'

tag = 'FluxPointsDataset'

Methods Documentation

copy(self, name=None)

A deep copy.

data_shape(self)

Shape of the flux points data (tuple).

flux_pred(self)

Compute predicted flux.

classmethod from_dict(data, models)

Create flux point dataset from dict.

Parameters

datadict

Dict containing data to create dataset from.

modelslist of SkyModel

List of model components.

Returns

datasetFluxPointsDataset

Flux point datasets.

peek(self, method='diff/model', **kwargs)

Plot flux points, best fit model and residuals.

Parameters

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

Method used to compute the residuals, see MapDataset.residuals()

plot_residuals(self, ax=None, method='diff', **kwargs)

Plot flux point residuals.

Parameters

axAxes

Axes object.

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

Method used to compute the residuals, see MapDataset.residuals()

**kwargsdict

Keyword arguments passed to errorbar.

Returns

axAxes

Axes object.

plot_spectrum(self, ax=None, fp_kwargs=None, model_kwargs=None)

Plot spectrum including flux points and model.

Parameters

axAxes

Axes object.

fp_kwargsdict

Keyword arguments passed to FluxPoints.plot.

model_kwargsdict

Keywords passed to SpectralModel.plot and SpectralModel.plot_error

Returns

axAxes

Axes object.

residuals(self, method='diff')

Compute the flux point residuals ().

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)

• norm='sqrt_model' for: (flux points - model)/sqrt(model)

Returns

residualsndarray

Residuals array.

stat_array(self)

Fit statistic array.

stat_sum(self)

Total statistic given the current model parameters.

to_dict(self, filename='')

Convert to dict for YAML serialization.

write(self, filename, overwrite=True, **kwargs)

Write flux point dataset to file.

Parameters

filenamestr

Filename to write to.

overwritebool

Overwrite existing file.

**kwargsdict

Keyword arguments passed to write.