Last modified: December 2023

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AHELP for CIAO 4.16 Sherpa


Context: plotting


Return the data used by plot_pvalue.


get_pvalue_plot(null_model=None, alt_model=None, conv_model=None, id=1,
otherids=(), num=500, bins=25, numcores=None, recalc=False)

conv_model - optional
id - int or str, optional
otherids - sequence of int or str, optional
num - int, optional
bins - int, optional
numcores - optional
recalc - bool, optional


Access the data arrays and preferences defining the histogram plot produced by the `plot_pvalue` function, a histogram of the likelihood ratios comparing fits of the null model to fits of the alternative model using faked data with Poisson noise. Data returned includes the likelihood ratio computed using the observed data, and the p-value, used to reject or accept the null model.


Example 1

Return the values from the last call to `plot_pvalue` :

>>> pvals = get_pvalue_plot()
>>> pvals.ppp

Example 2

Run 500 simulations for the two models and print the results:

>>> pvals = get_pvalue_plot(mdl1, mdl2, recalc=True, num=500)
>>> print(pvals)


The parameters for this function are:

Parameter Definition
null_model The model expression for the null hypothesis.
alt_model The model expression for the alternative hypothesis.
conv_model An expression used to modify the model so that it can be compared to the data (e.g. a PSF or PHA response).
id The data set that provides the data. The default is 1.
otherids Other data sets to use in the calculation.
num The number of simulations to run. The default is 500.
bins The number of bins to use to create the histogram. The default is 25.
numcores The number of CPU cores to use. The default is to use all the cores on the machine.
recalc The default value ( False ) means that the results from the last call to `plot_pvalue` or `get_pvalue_plot` are returned. If True , the values are re-calculated.


The `set_rng` routine is used to control how the random numbers are generated.


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, plot_marx_spectrum, prof_data, prof_delchi, prof_fit, prof_fit_delchi, prof_fit_resid, prof_model, prof_resid, prof_source
get_arf_plot, get_bkg_chisqr_plot, get_bkg_delchi_plot, get_bkg_fit_plot, get_bkg_model_plot, get_bkg_plot, get_bkg_ratio_plot, get_bkg_resid_plot, get_bkg_source_plot
list_model_ids, show_bkg_model, show_bkg_source
add_model, add_user_pars, clean, create_model_component, delete_bkg_model, delete_model, delete_model_component, get_model, get_model_autoassign_func, get_model_component, get_model_component_image, get_model_component_plot, get_model_plot, get_num_par, get_num_par_frozen, get_num_par_thawed, get_order_plot, get_par, get_pileup_model, get_source, get_source_component_image, get_source_component_plot, get_source_contour, get_source_image, get_source_plot, get_xsabund, get_xscosmo, get_xsxsect, get_xsxset, image_model, image_model_component, image_source, image_source_component, integrate, link, load_table_model, load_template_interpolator, load_template_model, load_user_model, normal_sample, reset, save_model, save_source, set_bkg_model, set_bkg_source, set_full_model, set_model, set_model_autoassign_func, set_pileup_model, set_source, set_xsabund, set_xscosmo, set_xsxsect, set_xsxset, t_sample, uniform_sample
get_cdf_plot, get_energy_flux_hist, get_pdf_plot, get_photon_flux_hist, get_pvalue_results, get_split_plot, plot, plot_arf, plot_bkg, plot_bkg_chisqr, plot_bkg_delchi, plot_bkg_fit, plot_bkg_fit_delchi, plot_bkg_fit_resid, plot_bkg_model, plot_bkg_ratio, plot_bkg_resid, plot_bkg_source, plot_cdf, plot_chisqr, plot_data, plot_delchi, plot_energy_flux, plot_fit, plot_fit_delchi, plot_fit_resid, plot_model, plot_model_component, plot_order, plot_pdf, plot_photon_flux, plot_pvalue, plot_ratio, plot_resid, plot_scatter, plot_source, plot_source_component, plot_trace, set_xlinear, set_xlog, set_ylinear, set_ylog
delete_psf, load_conv, plot_kernel
save_delchi, save_resid
get_chisqr_plot, get_delchi_plot
calc_chisqr, calc_energy_flux, calc_model_sum, calc_photon_flux, calc_source_sum, calc_stat, eqwidth
contour_model, contour_ratio, contour_resid