plot

sherpa.astro.ui.plot(*args, **kwargs)

Create one or more plot types.

The plot function creates one or more plots, depending on the arguments it is sent: a plot type, followed by optional identifiers, and this can be repeated. If no data set identifier is given for a plot type, the default identifier - as returned by get_default_id - is used.

Changed in version 4.12.2: Keyword arguments, such as alpha and ylog, can be sent to each plot.

Raises

sherpa.utils.err.ArgumentErr – The data set does not support the requested plot type.

See also

get_default_id

Return the default data set identifier.

sherpa.astro.ui.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.

Notes

The supported plot types depend on the data set type, and include the following list. There are also individual functions, with plot_ prepended to the plot type, such as plot_data (the bkg variants use a prefix of plot_bkg_). There are also several multiple-plot commands, such as plot_fit_ratio, plot_fit_resid, and plot_fit_delchi.

arf

The ARF for the data set (only for DataPHA data sets).

bkg

The background.

bkgchisqr

The chi-squared statistic calculated for each bin when fitting the background.

bkgdelchi

The residuals for each bin, calculated as (data-model) divided by the error, for the background.

bkgfit

The data (as points) and the convolved model (as a line), for the background data set.

bkgmodel

The convolved background model.

bkgratio

The residuals for each bin, calculated as data/model, for the background data set.

bkgresid

The residuals for each bin, calculated as (data-model), for the background data set.

bkgsource

The un-convolved background model.

chisqr

The chi-squared statistic calculated for each bin.

data

The data (which may be background subtracted).

delchi

The residuals for each bin, calculated as (data-model) divided by the error.

fit

The data (as points) and the convolved model (as a line).

kernel

The PSF kernel associated with the data set.

model

The convolved model.

psf

The unfiltered PSF kernel associated with the data set.

ratio

The residuals for each bin, calculated as data/model.

resid

The residuals for each bin, calculated as (data-model).

source

The un-convolved model.

The plots can be specialized for a particular data type, such as the set_analysis command controlling the units used for PHA data sets.

See the documentation for the individual routines for information on how to configure the plots.

The plot capabilities depend on what plotting backend, if any, is installed. If there is none available, a warning message will be displayed when sherpa.ui or sherpa.astro.ui is imported, and the plot set of commands will not create any plots. The choice of back end is made by changing the options.plot_pkg setting in the Sherpa configuration file.

The keyword arguments are sent to each plot (so care must be taken to ensure they are valid for all plots).

Examples

Plot the data for the default data set. This is the same as plot_data.

>>> plot("data")

Plot the data for data set 2.

>>> plot("data", 2)

Plot the data and ARF for the default data set, in two seaparate plots.

>>> plot("data", "arf")

Plot the fit (data and model) for data sets 1 and 2, in two separate plots.

>>> plot("fit", 1, "fit", 2)

Plot the fit (data and model) for data sets “fit” and “jet”, in two separate plots.

>>> plot("fit", "nucleus", "fit", "jet")

Draw the data and model plots both with a log-scale for the y axis:

>>> plot("data", "model", ylog=True)

Plot the backgrounds for dataset 1 using the ‘up’ and ‘down’ components (in this case the background identifier):

>>> plot('bkg', 1, 'up', 'bkg', 1, 'down')