plot_delchi

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

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

This function displays the residuals (data - model) divided by the error, for a data set.

Parameters:

• id (int or str, optional) – The data set. If not given then the default identifier is used, as returned by get_default_id.
• replot (bool, optional) – Set to True to use the values calculated by the last call to plot_delchi. 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.IdentifierErr – If the data set does not exist or a source expression has not been set.

See also

get_delchi_plot()

Return the data used by plot_delchi.

get_default_id()

Return the default data set identifier.

plot()

Create one or more plot types.

plot_chisqr()

Plot the chi-squared value for each point in a data set.

plot_ratio()

Plot the ratio of data to model for a data set.

plot_resid()

Plot the residuals (data - model) for a data set.

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 residuals for the default data set, divided by the error value for each bin:

>>> plot_delchi()

Overplot the values from the ‘core’ data set on those from the ‘jet’ dataset:

>>> plot_delchi('jet')
>>> plot_delchi('core', overplot=True)