Chandra X-Ray Observatory
Skip to the navigation links
Last modified: December 2010

Jump to: Description · Examples · Bugs · See Also

AHELP for CIAO 4.3 Sherpa v1


Context: filtering


Apply an exclude filter to 1-D data by data set ID


ignore_id( ids, [lo,hi] )
ignore_id( ids, expr )


Specifies a portion of data to be excluded from the 1-D data set(s) supplied by ID. To operate on all data sets without having to list the IDs, use the ignore command ("ahelp ignore").

  • ids - a list of ids of the data sets to filter; default=None
  • lo: lower bound of the filter; default=None
  • hi: upper bound of the filter; default=None
  • expr: a filter expression to ignore an intersection of filters, e.g. "0.1:5, 6:7". Range filtering allows ":#" and "#:", which excludes an open-ended range of data up to or beginning at the given value (#), respectively.

The units for the limits are determined by the "units" field of the data structure: channels, energy (keV), or wavelength (angstrom). The value can be obtained by using the get_analysis command ("ahelp get_analysis").

If the data is binned and the endpoint of the interval falls within a bin, the entire bin is included in the filter.

Two-dimensional Data Filtering

To apply an exclude filter to 2D data, use the ignore2d command ("ahelp ignore2d") or the ignore2d_id command ("ahelp ignore2d_id").

Example 1

sherpa> ignore_id()

When the function ignore_id is called with no arguments, the filter will ignore all data points on the grid of the default data set ID.

Example 2

sherpa> ignore_id(2, "0.1:5, 6:7")

Ignore the bins in dataset id=2 between 0.1 and 5 keV and between 6 and 7 keV.

Example 3

sherpa> ignore_id(2, 0.1, 6.0)

Supplying an interval will apply a filter to all the specified data set IDs. Here, all data points above the value 0.1 and below the value 0.6 are excluded in the data set "2".

Example 4

sherpa> ignore_id("bkg", 0.1, None)

All data points above the value 0.1 are excluded in the data set "bkg".

Example 5

sherpa> ignore_id([2,4], None, 6.0)

All data points below the value 6.0 are ignored in data sets "2" and "4".


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

See Also

get_filter, ignore, ignore2d, ignore2d_id, ignore_bad, notice, notice2d, notice2d_id, notice_id, show_filter

Last modified: December 2010
Smithsonian Institute Smithsonian Institute

The Chandra X-Ray Center (CXC) is operated for NASA by the Smithsonian Astrophysical Observatory. 60 Garden Street, Cambridge, MA 02138 USA.   Email: Smithsonian Institution, Copyright © 1998-2019. All rights reserved.