get_staterror¶

sherpa.astro.ui.get_staterror(id=None, filter=False, bkg_id=None)¶

Return the statistical error on the dependent axis of a data set.

Parameters:	id (int or str, optional) – The identifier for the data set to use. If not given then the default identifier is used, as returned by get_default_id. filter (bool, optional) – Should the filter attached to the data set be applied to the return value or not. The default is `False`. bkg_id (int or str, optional) – Set if the values returned should be from the given background component, instead of the source data set.
Returns:	axis – The statistical error for each data point. This may be estimated from the data (e.g. with the `chi2gehrels` statistic) or have been set explicitly (set_staterror). For PHA data sets, the return array will match the grouping scheme applied to the data set.
Return type:	array
Raises:	`sherpa.utils.err.IdentifierErr` – If the data set does not exist.

See also

get_error(): Return the errors on the dependent axis of a data set.
get_indep(): Return the independent axis of a data set.
get_syserror(): Return the systematic errors on the dependent axis of a data set.
list_data_ids(): List the identifiers for the loaded data sets.
set_staterror(): Set the statistical errors on the dependent axis of a data set.

Examples

If not explicitly given, the statistical errors on a data set may be calculated from the data values (the independent axis), depending on the chosen statistic:

>>> load_arrays(1, [10,15,19], [4,5,9])
>>> set_stat('chi2datavar')
>>> get_staterror()
array([ 2.        ,  2.23606798,  3.        ])
>>> set_stat('chi2gehrels')
>>> get_staterror()
array([ 3.17944947,  3.39791576,  4.122499  ])

If the statistical errors are set - either when the data set is created or with a call to set_staterror - then these values will be used, no matter the statistic:

>>> load_arrays(1, [10,15,19], [4,5,9], [2,3,5])
>>> set_stat('chi2datavar')
>>> get_staterror()
array([2, 3, 5])
>>> set_stat('chi2gehrels')
>>> get_staterror()
array([2, 3, 5])