Last modified: December 2023

AHELP for CIAO 4.16 Sherpa


Context: filtering


Include data in the fit.


notice(lo=None, hi=None, **kwargs)

lo - number or str, optional
hi - number, optional
bkg_id - int or str, optional


Select one or more ranges of data to include by filtering on the independent axis value. The filter is applied to all data sets.


Example 1

Since the `notice` call is applied to an un-filtered data set, the filter chooses only those points that lie within the range 12 <= X <= 18.

>>> load_arrays(1, [10, 15, 20, 30], [5, 10, 7, 13])
>>> notice(12, 28)
dataset 1: 10:30 -> 15:20 x
>>> get_dep(filter=True)
array([10,  7])

Example 2

As no limits are given, the whole data set is included:

>>> notice()
dataset 1: 15:20 -> 10:30 x
>>> get_dep(filter=True)
array([ 5, 10,  7, 13])

Example 3

The `ignore` call excludes the first two points, but the `notice` call adds back in the second point:

>>> ignore(hi=17)
dataset 1: 10:30 -> 20:30 x
>>> notice(12, 16)
dataset 1: 20:30 -> 15:30 x
>>> get_dep(filter=True)
array([10,  7, 13])

Example 4

Only include data points in the range 8<=X<=12 and 18<=X=22:

>>> ignore()
dataset 1: 15:30 x -> no data
>>> notice("8:12, 18:22")
dataset 1: no data -> 10 x
dataset 1: 10 -> 10,20 x
>>> get_dep(filter=True)
array([5, 7])

Example 5

The messages from `notice` and `ignore` use the standard Sherpa logging infrastructure, and so can be ignored by using `SherpaVerbosity` :

>>> from sherpa.utils.logging import SherpaVerbosity
>>> with SherpaVerbosity("WARN"):
...     notice()


The parameters for this function are:

Parameter Definition
lo The lower bound of the filter (when a number) or a string expression listing ranges in the form a:b , with multiple ranges allowed, where the ranges are separated by a , . The term :b means include everything up to b (an exclusive limit for integrated datasets), and a: means include everything that is higher than, or equal to, a .
hi The upper bound of the filter when lo is not a string.
bkg_id The filter will be applied to the associated background component of the data set if bkg_id is set. Only PHA data sets support this option; if not given, then the filter is applied to all background components as well as the source data.


The order of `ignore` and `notice` calls is important, and the results are a union, rather than intersection, of the combination.

If `notice` is called on an un-filtered data set, then the ranges outside the noticed range are excluded: it can be thought of as if `ignore` had been used to remove all data points. If `notice` is called after a filter has been applied then the filter is applied to the existing data.

For binned data sets, the bin is included if the noticed range falls anywhere within the bin, but excluding the hi value (except for PHA data sets when using channel units).

The units used depend on the analysis setting of the data set, if appropriate.

To filter a 2D data set by a shape use `notice2d` .

The report of the change in the filter expression can be controlled with the `SherpaVerbosity` context manager, as shown in the examples below.

Changes in CIAO

Changed in CIAO 4.15

The change in the filter is now reported for each dataset.

Changed in CIAO 4.14

Integrated data sets - so Data1DInt and DataPHA when using energy or wavelengths - now ensure that the `hi` argument is exclusive and better handling of the `lo` argument when it matches a bin edge. This can result in the same filter selecting a smaller number of bins than in earlier versions of Sherpa.


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

See Also

group, group_adapt, group_adapt_snr, group_bins, group_counts, group_snr, group_width
get_filter, ignore, ignore2d, ignore2d_id, ignore_bad, ignore_id, notice2d, notice2d_id, notice_id, show_filter