Last modified: December 2020

URL: https://cxc.cfa.harvard.edu/sherpa/ahelp/get_error.html
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AHELP for CIAO 4.13 Sherpa v1

get_error

Context: data

Synopsis

Return the errors on the dependent axis of a data set.

Syntax

get_error(id=None, filter=False, bkg_id=None)

id - int or str, optional
filter - bool, optional
bkg_id - int or str, optional

Description

The function returns the total errors (a quadrature addition of the statistical and systematic errors) on the values (dependent axis) of a data set or its background. The individual components can be retrieved with the `get_staterror` and `get_syserror` functions.


Examples

Example 1

Return the error values for the default data set, ignoring any filter applied to it:

>>> err = get_error()

Example 2

Ensure that the return values are for the selected (filtered) points in the default data set (the return array may be smaller than in the previous example):

>>> err = get_error(filter=True)

Example 3

Find the errors for the "core" data set and its two background components:

>>> err = get_error('core', filter=True)
>>> berr1 = get_error('core', bkg_id=1, filter=True)
>>> berr2 = get_error('core', bkg_id=2, filter=True)

PARAMETERS

The parameters for this function are:

Parameter Definition
id The identifier for the data set to use. If not given then the default identifier is used, as returned by `get_default_id` .
filter Should the filter attached to the data set be applied to the return value or not. The default is False .
bkg_id Set if the values returned should be from the given background component, instead of the source data set.

Return value

The return value from this function is:

errors -- The error for each data point, formed by adding the statistical and systematic errors in quadrature. For PHA data sets, the return array will match the grouping scheme applied to the data set. The size of this array depends on the `filter` argument.

Notes

The default behavior is to not apply any filter defined on the independent axes to the results, so that the return value is for all points (or bins) in the data set. Set the `filter` argument to `True` to apply this filter.


Bugs

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

See Also

confidence
get_conf, get_conf_results, get_covar, get_covar_opt, get_covar_results, get_covariance_results, get_int_proj, get_int_unc, get_proj, get_proj_opt, get_proj_results, get_projection_results, get_reg_proj, get_reg_unc
contrib
get_chart_spectrum, get_marx_spectrum
data
copy_data, dataspace1d, dataspace2d, datastack, delete_data, fake, get_areascal, get_arf, get_arf_plot, get_axes, get_backscal, get_bkg, get_bkg_arf, get_bkg_chisqr_plot, get_bkg_delchi_plot, get_bkg_fit_plot, get_bkg_model, get_bkg_model_plot, get_bkg_plot, get_bkg_ratio_plot, get_bkg_resid_plot, get_bkg_rmf, get_bkg_scale, get_bkg_source, get_bkg_source_plot, get_coord, get_counts, get_data, get_data_contour, get_data_contour_prefs, get_data_image, get_data_plot, get_data_plot_prefs, get_dep, get_dims, get_exposure, get_grouping, get_indep, get_quality, get_rmf, get_specresp, get_staterror, get_syserror, group, group_adapt, group_adapt_snr, group_bins, group_counts, group_snr, group_width, load_ascii, load_data, load_grouping, load_quality, set_data, set_quality, ungroup, unpack_ascii, unpack_data
filtering
get_filter, load_filter, set_filter
fitting
calc_stat_info, get_stat_info
info
get_default_id, list_data_ids, list_response_ids, list_stats
methods
get_draws, get_iter_method_name, get_iter_method_opt, get_method, get_method_name, get_method_opt
modeling
clean, get_model, 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_response, get_source, get_source_component_image, get_source_component_plot, get_source_contour, get_source_image, get_source_plot, image_source
plotting
get_split_plot, plot_data, set_xlinear, set_xlog, set_ylinear, set_ylog
psfs
get_psf, get_psf_contour, get_psf_image, get_psf_plot
saving
save_error, save_filter, save_grouping, save_quality, save_staterror, save_syserror
statistics
get_chisqr_plot, get_delchi_plot, get_prior, get_sampler, get_stat, get_stat_name
utilities
calc_data_sum, calc_data_sum2d, calc_ftest, calc_kcorr, calc_mlr, calc_model_sum2d, calc_source_sum2d, get_analysis, get_rate
visualization
contour, contour_data, contour_ratio, histogram1d, histogram2d, image_data, image_getregion, rebin