plot_chisqr

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

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

This function displays the square of 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_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.IdentifierErr – If the data set does not exist or a source expression has not been set.

See also

get_chisqr_plot()

Return the data used by plot_chisqr.

get_default_id()

Return the default data set identifier.

plot()

Create one or more plot types.

plot_delchi()

Plot the ratio of residuals to error for 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 chi-quare values for each point in the default data set:

>>> plot_chisqr()

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

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