Return the filter expression for a data set.

This returns the filter expression, created by one or more calls to ignore and notice, for the data set.

Parameters: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.
Returns:filter – The empty string or a string expression representing the filter used. For PHA data dets the units are controlled by the analysis setting for the data set.
Return type:str
Raises:sherpa.utils.err.ArgumentErr – If the data set does not exist.

See also

Exclude data from the fit.
Load the filter array from a file and add to a data set.
Include data in the fit.
Save the filter array to a file.
Show any filters applied to a data set.
Set the filter array of a data set.


The default filter is the full dataset, given in the format lowval:hival (both are inclusive limits):

>>> load_arrays(1, [10, 15, 20, 25], [5, 7, 4, 2])
>>> get_filter()

The notice call restricts the data to the range between 14 and 30. The resulting filter is the combination of this range and the data:

>>> notice(14, 30)
>>> get_filter()

Ignoring the point at x=20 means that only the points at x=15 and x=25 remain, so a comma-separated list is used:

>>> ignore(19, 22)
>>> get_filter()

The filter equivalent to the per-bin array of filter values:

>>> set_filter([1, 1, 0, 1])
>>> get_filter()

Return the filter for data set 3:

>>> get_filter(3)