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Last modified: December 2010

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AHELP for CIAO 4.3 Sherpa v1


Context: filtering


Apply an include filter to 1D data by dataset id


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


The notice_id command specifies the portion of 1D data to be included in the analysis. The filter is applied to the specified dataset ids; to operate on all datasets without having to list the ids, use the notice command ("ahelp notice").

  • 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 notice an intersection of filters, e.g. "0.1:5, 6:7". Range filtering allows ":#" and "#:", which includes 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 no limits are supplied, all data points in the specified datasets are included. Noticing the entire set is a method of clearing any filters that have been applied. It is also possible to specify just a lower limit or just an upper limit; the unspecified value will remain at the data minimum or maximum.

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 include filter to 2D data, use the notice2d command ("ahelp notice2d") or the notice2d_id command ("ahelp notice2d_id").

Example 1

sherpa> notice_id([1,2])

The command is called without any limits defined, so all data points in datasets 1 and 2 are included.

Example 2

sherpa> notice_id("src", 1.0, 6.0)

Apply a filter to notice_id the range 1.0-6.0 keV in the dataset "src".

Example 3

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

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

Example 4

sherpa> notice_id(2, 200,)
sherpa> notice_id(2, 200, None)

These commands are two equivalent ways of applying an open-ended notice_id filter to data in channel space. The lower limit of the filter for dataset 2 is set to 200 channels, but the upper limit is undefined.

Example 5

sherpa> notice_id([2,4], , 8.0)
sherpa> notice_id([2,4], None, 8.0)

These commands are two equivalent ways of applying an open-ended notice_id filter to data in energy space. The lower limit of the filter for datasets 2 and 4 is undefined and the upper limit is set to 8.0 keV.


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, ignore_id, notice, notice2d, notice2d_id, show_filter

Last modified: December 2010
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