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Last modified: December 2010

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AHELP for CIAO 4.3 Sherpa v1


Context: plotting


Plot information about background data


plot_bkg( [id], [bkg_id=None, replot=False, overplot=False] )
plot_bkg_chisqr ( [id], [bkg_id=None, replot=False, overplot=False] )
plot_bkg_delchi ( [id], [bkg_id=None, replot=False, overplot=False] )
plot_bkg_fit ( [id], [bkg_id=None, replot=False, overplot=False] )
plot_bkg_fit_delchi ( [id], [bkg_id=None, replot=False, overplot=False]
plot_bkg_fit_resid ( [id], [bkg_id=None, replot=False, overplot=False] )
plot_bkg_model ( [id], [bkg_id=None, replot=False, overplot=False] )
plot_bkg_ratio ( [id], [bkg_id=None, replot=False, overplot=False] )
plot_bkg_resid ( [id], [bkg_id=None, replot=False, overplot=False] )
plot_bkg_source ( [id], [lo=None, hi=None, bkg_id=None, replot=False,
overplot=False] )


There are a number of commands to plot information about the background data:

  • plot_bkg - background counts
  • plot_bkg_chisqr - background chi squared contributions
  • plot_bkg_delchi - background delta chi (residuals divided by background uncertainties)
  • plot_bkg_fit - background counts with fitted background model
  • plot_bkg_fit_delchi - background fit and background delta chi
  • plot_bkg_fit_resid - background fit and background residuals
  • plot_bkg_model - convolved background model
  • plot_bkg_ratio - background ratio (background measured counts divided by background predicted counts)
  • plot_bkg_resid - background residuals (measured background counts minus predicted background counts)
  • plot_bkg_source - unconvolved source model

The commands take the following options:

  • id - the id of the dataset to use; if not given, uses the default dataset id (id=1 by default, see "ahelp get_default_id")
  • bkg_id - the id of the background to use, e.g. if more than one background is associated with the data; default is the first background dataset
  • lo - lower bound of the desired plotting range; default=None
  • hi - high bound of the desired plotting range; default= None
  • lo - (plot_bkg_source only) lower limit of the plot in the same units as the data (energy [keV] or wavelength [A]); default=None, which uses the value from the response file (ENERG_LO)
  • hi - (plot_bkg_source only) upper limit of the plot in the same units as the data (energy [keV] or wavelength [A]); default=None, which uses the value from the response file (ENERG_HI)
  • overplot - should the new plot be overlaid in the plotting window? False (default)=clear the window, True=overplot on any existing plots

The plot is displayed in a ChIPS plotting window. If there is no plotting window open, one is created. If a plotting window exists, the overplot parameter value determines whether the new plot is overlaid on any existing plots in the window or if the window is cleared before the plot is drawn.

ChIPS commands may be used within Sherpa to modify plot characteristics and create hardcopies; refer to the ChIPS website for information.

Plotting Multiple Objects

To plot multiple Sherpa objects - e.g. data, model, fit, residuals - in a single window, use the plot command.

Example 1

sherpa> plot_bkg()

Plot the first background set (if there is more than one) associated with the default dataset.

Example 2

sherpa> plot_bkg("src", "bg2", overplot=True)

Plot the background "bg2" associated with dataset "src", overlaying it on any existing plots.


See the bugs pages on the Sherpa website for an up-to-date listing of known bugs.

See Also

get_data_prof, get_data_prof_prefs, get_delchi_prof, get_delchi_prof_prefs, get_fit_prof, get_model_prof, get_model_prof_prefs, get_resid_prof, get_resid_prof_prefs, get_source_prof, get_source_prof_prefs, plot_chart_spectrum, prof_data, prof_delchi, prof_fit, prof_fit_delchi, prof_fit_resid, prof_model, prof_resid, prof_source
get_arf_plot, get_bkg, get_bkg_plot, set_bkg, subtract, unsubtract
list_bkg_ids, show_bkg_model, show_bkg_source
get_energy_flux_hist, get_photon_flux_hist, get_split_plot, plot, plot_arf, plot_chisqr, plot_data, plot_delchi, plot_energy_flux, plot_fit, plot_model, plot_model_component, plot_order, plot_photon_flux, plot_ratio, plot_resid, plot_source, plot_source_component, set_xlinear, set_xlog, set_ylinear, set_ylog
get_chisqr_plot, get_delchi_plot

Last modified: December 2010
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