plot_bkg

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

Plot the background values for a PHA data set.

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. 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.

See also

get_bkg_plot()

Return the data used by plot_bkg.

get_default_id()

Return the default data set identifier.

plot()

Create one or more plot types.

set_analysis()

Set the units used when fitting and displaying spectral data.

set_xlinear()

New plots will display a linear X axis.

set_xlog()

New plots will display a logarithmically-scaled X axis.

set_ylinear()

New plots will display a linear Y axis.

set_ylog()

New plots will display a logarithmically-scaled Y axis.

Examples

Plot the background from the default data set:

>>> plot_bkg()

Overplot the background from the ‘jet’ data set on the data. There is no scaling for differences in aperture or exposure time:

>>> plot_data('jet')
>>> plot_bkg('jet', overplot=True)

Compare the first two background components of data set 1:

>>> plot_bkg(1, 1)
>>> plot_bkg(1, 2, overplot=True)