calc_data_sum

sherpa.astro.utils.calc_data_sum(data, lo=None, hi=None)

Sum up the data values over a pass band.

Parameters:

• data – The data object to use.

• lo (number, optional) – If both are None or both are set then use the full dataset. If only one is set then use the data count for that bin. The units for lo and hi are given by the current analysis setting of the data parameter.

• hi (number, optional) – If both are None or both are set then use the full dataset. If only one is set then use the data count for that bin. The units for lo and hi are given by the current analysis setting of the data parameter.

Returns:

dsum – The sum of the data values that lie within the given limits. If a background estimate has been subtracted from the data set then the calculation will use the background-subtracted values.

Return type:

number

See also

calc_data_sum2d

Sum up the data values of a 2D data set.

calc_model_sum

Sum up the fitted model over a pass band.

calc_energy_flux

Integrate the source model over a pass band.

calc_photon_flux

Integrate the source model over a pass band.

calc_source_sum

Sum up the source model over a pass band.

set_model

Set the source model expression for a data set.

Notes

The units of lo and hi are determined by the analysis setting for the data set (e.g. data.get_analysis).

Any existing filter on the data set - e.g. as created by ignore or notice - is ignored by this function.

If a grouping scheme has been applied to the data set that it will be used. This can change the results, since the first and last bins of the selected range may extend outside the requested range.

Examples

Calculate the number of counts over the ranges 0.5 to 2 and 0.5 to 7 keV, first using the observed signal and then, for the 0.5 to 2 keV band - the background-subtraced estimate:

>>> set_analysis('energy')
>>> calc_data_sum(data, 0.5, 2)
745.0
>>> calc_data_sum(data, 0.5, 7)
60.0
>>> data.subtract()
>>> calc_data_sum(data, 0.5, 2)
730.9179738207356