Last modified: December 2023

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AHELP for CIAO 4.16 Sherpa


Context: data


Load the systematic errors from a file.


load_syserror(id, filename=None, bkg_id=None, *args, **kwargs)

id - int or str, optional
filename - str
bkg_id - int or str, optional
ncols - int, optional
colkeys - array of str, optional
sep - str, optional
comment - str, optional


Read in a column or image from a file and use the values as the systematic errors for a data set.


Example 1

Read in the first column from 'tbl.dat':

>>> load_syserror('tbl.dat')

Example 2

Use the column labelled 'col3'

>>> load_syserror('tbl.dat', colkeys=['col3'])

Example 3

When using the Crates I/O library, the file name can include CIAO Data Model syntax, such as column selection:

>>> load_syserror('tbl.dat[cols col3]')

Example 4

Read in the first column from the file 'errors.fits' as the systematic errors for the 'core' data set:

>>> load_syserror('core', 'errors.fits')

Example 5

The data set labelled 'img' is loaded from the file 'image.fits' and the systematic errors from 'syserr.fits'. The dimensions of the two images must be the same.

>>> load_image('img', 'image.fits')
>>> load_syserror('img', 'syserr.fits')


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` .
filename The name of the file to read in. Supported formats depends on the I/O library in use (Crates or AstroPy) and the type of data set (e.g. 1D or 2D).
bkg_id Set to identify which background component to set. The default value ( none ) means that this is for the source component of the data set.
ncols The number of columns to read in (the first ncols columns in the file).
colkeys An array of the column name to read in. The default is none .
sep The separator character. The default is ' ' .
comment The comment character. The default is '#' .


The function does not follow the normal Python standards for parameter use, since it is designed for easy interactive use. When called with a single un-named argument, it is taken to be the `filename` parameter. If given two un-named arguments, then they are interpreted as the `id` and `filename` parameters, respectively. The remaining parameters are expected to be given as named arguments.


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

See Also

dataspace1d, dataspace2d, datastack, fake, load_arf, load_arrays, load_ascii, load_bkg, load_bkg_arf, load_bkg_rmf, load_data, load_grouping, load_image, load_multi_arfs, load_multi_rmfs, load_pha, load_quality, load_rmf, load_staterror, load_table, pack_image, pack_pha, pack_table, set_syserror, unpack_arf, unpack_arrays, unpack_ascii, unpack_bkg, unpack_data, unpack_image, unpack_pha, unpack_rmf, unpack_table
get_default_id, list_bkg_ids, list_data_ids
add_model, add_user_pars, load_table_model, load_template_interpolator, load_template_model, load_user_model, save_model, save_source
save_arrays, save_data, save_delchi, save_error, save_filter, save_grouping, save_image, save_pha, save_quality, save_resid, save_staterror, save_syserror, save_table