set_staterror
- sherpa.astro.ui.set_staterror(id, val=None, fractional=False, bkg_id: IdType | None = None) None
Set the statistical errors on the dependent axis of a data set.
These values override the errors calculated by any statistic, such as
chi2gehrels
orchi2datavar
.- 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
.val (array or scalar) – The systematic error.
fractional (bool, optional) – If
False
(the default value), then theval
parameter is the absolute value, otherwise theval
parameter represents the fractional error, so the absolute value is calculated asget_dep() * val
(andval
must be a scalar).bkg_id (int, str, or None, optional) – Set to identify which background component to set. The default value (
None
) means that this is for the source component of the data set.
See also
load_staterror
Load the statistical errors from a file.
load_syserror
Load the systematic errors from a file.
set_syserror
Set the systematic errors on the dependent axis of a data set.
get_error
Return the errors on the dependent axis of a data set.
Notes
The function does not follow the normal Python standards for parameter use, since it is designed for easy interactive use. When called with a single un-named argument, it is taken to be the
val
parameter. If given two un-named arguments, then they are interpreted as theid
andval
parameters, respectively.Examples
Set the statistical error for the default data set to the value in
dys
(a scalar or an array):>>> set_staterror(dys)
Set the statistical error on the ‘core’ data set to be 5% of the data values:
>>> set_staterror('core', 0.05, fractional=True)