Last modified: December 2015

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AHELP for CIAO 4.12 Sherpa v1


Context: confidence


Return the confidence data defining an interval projection plot


get_int_proj(par=None, id=None, otherids=None, recalc=False, min=None,
max=None, nloop=20, delv=None, fac=1, log=False, numcores=None)


The get_int_proj() function returns the data defining a confidence plot of fit statistic versus model parameter value for a single thawed model parameter, produced by the int_proj() function. (The parameter value is varied on the computed grid until the fit statistic is increased by delta_S, which is a function of sigma. For example, delta_S = 1 if the statistic is chi^2 and fac = 1 . All other thawed parameters are allowed to float to new best-fit values at each step, instead of being fixed to the initial best-fit values.)

The get_int_proj() function returns information on the most recent confidence plot produced with int_proj(), independent of the arguments supplied, unless the 'recalc' argument is set to True . For example, if an interval projection confidence plot is produced for the amplitude of a power law model, and then get_int_proj() is used to obtain confidence data on the gamma parameter of the power law model, the information returned by get_int_proj() will correspond to the confidence plot of the amplitude parameter, *unless* the 'recalc' argument is switched on.

The computationally intensive projection function is parallelized to make use of multi-core systems to provide significant improvements in efficiency compared to previous releases of Sherpa; the 'numcores' argument may be used to specify how the cores should be used when projection is run.


Example 1

sherpa> print(get_int_proj())

When called with no arguments from within the print command, get_int_proj() returns the confidence data defining the most recently produced interval projection plot.

Example 2

sherpa> print(get_int_proj("p1.gamma", id=2, recalc=True))

This command will calculate and return the interval projection confidence data for the gamma parameter of power law model 'p1', which is assigned to data set 2.

sherpa> print(get_int_proj("p1.gamma", id=2, recalc=True))

x     = [-10.      -8.9474  -7.8947 ...,   7.8947   8.9474  10.    ]
y     = [ 436.2093  436.3852  436.0802 ...,  442.5094  443.0242  443.3257]
min   = -10.0
max   = 10.0
nloop = 20
delv  = None
fac   = 1
log   = False


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

See Also

conf, covariance, get_conf, get_covar, get_int_unc, get_proj, get_reg_proj, get_reg_unc, int_proj, int_unc, projection, reg_proj, reg_unc, set_conf_opt, set_covar_opt, set_proj_opt
get_chart_spectrum, get_marx_spectrum
get_areascal, get_arf, get_arf_plot, get_axes, get_backscal, get_bkg, get_bkg_plot, get_bkg_scale, get_coord, get_counts, get_data, get_data_plot, get_dep, get_dims, get_error, get_exposure, get_grouping, get_indep, get_quality, get_rmf, get_specresp, get_staterror, get_syserror
calc_stat_info, get_fit, get_stat_info
get_default_id, list_stats
get_draws, get_iter_method_name, get_iter_method_opt, get_method
get_model, get_model_component, get_model_component_image, get_model_component_plot, get_model_plot, get_num_par, get_order_plot, get_par, get_pileup_model, get_response, get_source, get_source_component_image, get_source_component_plot, image_source
get_kernel, get_psf
get_chisqr_plot, get_delchi_plot, get_prior, get_sampler, get_stat
get_analysis, get_rate
get_ratio, get_resid, image_getregion