sherpa.astro.ui.load_syserror(id, filename=None, bkg_id=None, *args, **kwargs)

Load the systematic errors from a file.

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

  • id (int or str, optional) – The identifier for the data set to use. If not given then the default identifier is used, as returned by get_default_id.

  • filename (str) – 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 (int or str, optional) – 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 (int, optional) – The number of columns to read in (the first ncols columns in the file).

  • colkeys (array of str, optional) – An array of the column name to read in. The default is None.

  • sep (str, optional) – The separator character. The default is ' '.

  • comment (str, optional) – The comment character. The default is '#'.

See also


Return the systematic error on the dependent axis of a data set.


Load the statistical errors from a file.


Set the systematic errors on the dependent axis of a data set.


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.


Read in the first column from ‘tbl.dat’:

>>> load_syserror('tbl.dat')

Use the column labelled ‘col3’

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

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]')

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

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

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')