Last modified: December 2020

URL: https://cxc.cfa.harvard.edu/sherpa/ahelp/set_grouping.html
AHELP for CIAO 4.13 Sherpa v1

set_grouping

Context: data

Synopsis

Apply a set of grouping flags to a PHA data set.

Syntax

set_grouping(id, val=None, bkg_id=None)

id - int or str, optional
val - array of int
bkg_id - int or str, optional

Description

A group is indicated by a sequence of flag values starting with 1 and then -1 for all the channels in the group, following [1] . Setting the grouping column automatically turns on the grouping flag for that data set.


Examples

Example 1

Copy the grouping array from data set 2 into the default data set:

>>> grp = get_grouping(2)
>>> set_grouping(grp)

Example 2

Copy the grouping from data set "src1" to the source and the first background data set of "src2":

>>> grp = get_grouping("src1")
>>> set_grouping("src2", grp)
>>> set_grouping("src2", grp, bkg_id=1)

PARAMETERS

The parameters for this function are:

Parameter Definition
id The identifier for the data set to use. If not given then the default identifier is used, as returned by `get_default_id` .
val This must be an array of grouping values of the same length as the data array.
bkg_id Set to group the background associated with the 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 the `id` and `val` parameters, respectively.

The meaning of the grouping column is taken from [1] , which says that +1 indicates the start of a bin, -1 if the channel is part of group, and 0 if the data grouping is undefined for all channels.

References


Bugs

See the bugs pages on the Sherpa website for an up-to-date listing of known bugs.

See Also

confidence
set_conf_opt, set_covar_opt, set_proj_opt
data
get_grouping, group, group_adapt, group_adapt_snr, group_bins, group_counts, group_snr, group_width, load_grouping, set_areascal, set_arf, set_backscal, set_bkg, set_coord, set_counts, set_data, set_dep, set_exposure, set_quality, set_rmf, set_staterror, set_syserror, ungroup
filtering
set_filter
methods
set_iter_method, set_iter_method_opt, set_method, set_method_opt
modeling
get_par, get_xsabund, get_xscosmo, get_xsxsect, get_xsxset, set_bkg_model, set_bkg_source, set_full_model, set_model, set_par, set_pileup_model, set_source, set_xsabund, set_xscosmo, set_xsxsect, set_xsxset
saving
save_grouping
statistics
set_prior, set_sampler, set_sampler_opt, set_stat
utilities
set_analysis, set_default_id
visualization
image_setregion