plot_bkg_chisqr¶

sherpa.astro.ui.plot_bkg_chisqr(id=None, bkg_id=None, **kwargs)¶

Plot the chi-squared value for each point of the background of a PHA data set.

Display the square of the residuals (data-model) divided by the error values for the background of a PHA data set when it is being fit, rather than subtracted from the source.

Parameters:

id (int or str, optional) – The data set that provides the data. If not given then the default identifier is used, as returned by get_default_id.
bkg_id (int or str, optional) – Identify the background component to use, if there are multiple ones associated with the data set.
replot (bool, optional) – Set to True to use the values calculated by the last call to plot_bkg_chisqr. The default is False.
overplot (bool, optional) – If True then add the data to an exsiting plot, otherwise create a new plot. The default is False.

Raises:

sherpa.utils.err.ArgumentErr – If the data set does not contain PHA data.
sherpa.utils.err.IdentifierErr – If the bkg_id parameter is invalid.
sherpa.utils.err.ModelErr – If no model expression has been created for the background data.

See also

get_bkg_chisqr_plot(): Return the data used by plot_bkg_chisqr.
plot_bkg_delchi(): Plot the ratio of residuals to error for the background of a PHA data set.
plot_bkg_ratio(): Plot the ratio of data to model values for the background of a PHA data set.
plot_bkg_resid(): Plot the residual (data-model) values for the background of a PHA data set.
set_bkg_model(): Set the background model expression for a PHA data set.

Examples

>>> plot_bkg_chisqr()

>>> plot_bkg_chisqr('jet', bkg_id=1)
>>> plot_bkg_chisqr('jet', bkg_id=2, overplot=True)