Synopsis
Sample the fit statistic by taking the parameter values from an uniform distribution.
Syntax
uniform_sample(num: int = 1, factor: float = 4, id: int | str | None = None, otherids: Sequence[int | str] = (), numcores: int | None = None, clip: Literal['none'] | Literal['hard'] | Literal['soft'] = 'none') Returns: np.ndarray
Description
For each iteration (sample), change the thawed parameters by drawing values from a uniform distribution, and calculate the fit statistic.
Example
The model fit to the default data set has three free parameters. The median value of the statistic calculated by `uniform_sample` is returned:
>>> ans = uniform_sample(num=1000) >>> ans.shape (1000, 5) >>> np.median(ans[:,0]) 284.66534775948134
PARAMETERS
The parameters for this function are:
| Parameter | Type information | Definition |
|---|---|---|
| num | int, optional | The number of samples to use (default is 1). |
| factor | number, optional | Multiplier to expand the scale parameter (default is 4). |
| id | int, str, or None, optional | The data set that provides the data. If not given then all data sets with an associated model are used simultaneously. |
| otherids | sequence of int or str, optional | Other data sets to use in the calculation. |
| numcores | optional | The number of CPU cores to use. The default is to use all the cores on the machine. |
| clip | {'hard', 'soft', 'none'}, optional | What clipping strategy should be applied to the sampled parameters. The default ('none') applies no clipping, 'hard' uses the hard parameter limits, and 'soft' the soft limits. |
Return value
The return value from this function is:
A NumPy array table with the first column representing the statistic, the later columns the parameters used, and the last column indicating whether any parameter in the row was clipped. The number of rows is given by the num argument.
Changes in CIAO
Changed in CIAO 4.18
The random state returned by get_rng is now used for the sampling. The clip parameter has been added, and the return array now ends in a column indicating whether any parameter in the row was clipped.
Bugs
See the bugs pages on the Sherpa website for an up-to-date listing of known bugs.
See Also
- contrib
- 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
- data
- 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
- info
- list_model_ids, show_bkg_model, show_bkg_source
- modeling
- 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, 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, t_sample
- plotting
- get_cdf_plot, get_energy_flux_hist, get_pdf_plot, get_photon_flux_hist, get_pvalue_plot, 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
- psfs
- delete_psf, load_conv, plot_kernel
- saving
- save_delchi, save_resid
- statistics
- get_chisqr_plot, get_delchi_plot
- utilities
- calc_chisqr, calc_energy_flux, calc_model_sum, calc_photon_flux, calc_source_sum, calc_stat, eqwidth
- visualization
- contour_model, contour_ratio, contour_resid