sherpa.astro.ui.save_staterror(id, filename=None, bkg_id=None, ascii=True, clobber=False)

Save the statistical errors to a file.

If the statistical errors have not been set explicitly, then the values calculated by the statistic - such as chi2gehrels or chi2datavar - will be used.

  • 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 write the array to. The format is determined by the ascii argument.

  • bkg_id (int or str, optional) – Set if the background should be written out rather than the source.

  • ascii (bool, optional) – If False then the data is written as a FITS format binary table. The default is True. The exact format of the output file depends on the I/O library in use (Crates or AstroPy).

  • clobber (bool, optional) – If outfile is not None, then this flag controls whether an existing file can be overwritten (True) or if it raises an exception (False, the default setting).


sherpa.utils.err.IOErr – If filename already exists and clobber is False.

See also


Load the statistical errors from a file.


Save the errors to a file.


Save the systematic errors to a file.


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.

The output file contains the columns X and STAT_ERR.


Write out the statistical errors from the default data set to the file ‘errs.dat’.

>>> save_staterror('errs.dat')

Over-write the file it it already exists, and take the data from the data set “jet”:

>>> save_staterror('jet', 'err.out', clobber=True)

Write the data out in FITS format:

>>> save_staterror('staterr.fits', ascii=False)