plot_bkg_delchi

sherpa.astro.ui.plot_bkg_delchi(id: IdType | IdTypes | None = None, bkg_id: IdType | None = None, replot: bool = False, overplot: bool = False, clearwindow: bool = True, **kwargs) → None

Plot the ratio of residuals to error for the background of a PHA data set.

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

Changed in version 4.18.0: Multiple data sets can be displayed by using a list of identifiers. Per-plot options can now be given by using a list of values.

Changed in version 4.12.0: The Y axis is now always drawn using a linear scale.

Parameters:

idint, str, sequence of int or str, or None, optional

The data set that provides the data. If not given then the default identifier is used, as returned by get_default_id.

bkg_idint, str, or None, optional

Identify the background component to use, if there are multiple ones associated with the data set.

replotbool, optional

Set to True to use the values calculated by the last call to plot_bkg_ratio. The default is False.

overplotbool, optional

If True then add the data to an existing plot, otherwise create a new plot. The default is False.

clearwindowbool, optional

Should the existing plot area be cleared before creating this new plot (e.g. for multi-panel plots)?

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_delchi_plot

Return the data used by plot_bkg_delchi.

plot_bkg_chisqr

Plot the chi-squared value for each point of 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.

Notes

The ylog setting is ignored, and the Y axis is drawn using a linear scale.

Examples

>>> plot_bkg_delchi()

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