Module functions for assigning source and background filters from an array.
Integer_Type set_filter([Integer_Type,]Array_Type)
Integer_Type set_bfilter([Integer_Type,]Array_Type)
Success/Error Return Values: 1/0
Arguments:
(1) Dataset number (default 1)
(2) An array of source/background filter values
Note that if only one argument is provided, it is assumed to be an
array, and the dataset is assumed to be dataset 1.
The set_filter
and set_bfilter functions allow the user
to set new filters for source and background datasets.
The input array is a Short_Type, Long_Type,
or Integer_Type array of the same length as the
input (unfiltered) dataset for which a new filter is to
be defined.
If an input array element is zero, then the corresponding data bin is to
be ignored; non-zero,
and the corresponding bin is to be noticed/used.
One may use these functions in combination with
get_filter and get_bfilter to
define new methods of data filtering that go beyond those
currently coded in Sherpa;
e.g., filtering based on data amplitude. See example below.
See the related Sherpa commands
NOTICE
and
IGNORE
for more information.
Read in a 100-bin dataset, and filter out bins 10 to 60:
sherpa> DATA spec.dat
sherpa> a = [0:99]
sherpa> a[*] = 1
sherpa> a[[9:59]] = 0
sherpa> () = set_filter(1,a)
In this example, data are read into Sherpa, and then
the filter array a defined: step 1 defines a 100-bin-length
array, step 2 resets all elements to 1, and step 3 resets a subset of
the elements to 0 (bins to be ignored). Note that while the bins
are numbered 1 to 100 in the data, the analogous array indices are
0 to 99, so array elements 9 to 59 are reset.
The array is then sent to Sherpa, where it sets the
new filter.
Read in a 100-bin dataset, and filter out all bins with counts greater
than 65:
sherpa> DATA spec.dat
sherpa> WRITE DATA
Write X-Axis: Bin Y-Axis: Flux (Counts)
1 59
2 46
3 49
4 65
5 60
6 60
7 74
...
sherpa> d = get_data()
sherpa> a = where(d>65)
sherpa> printarr(a)
6
9
11
26
...
sherpa> f = get_filter()
sherpa> f[a] = 0
sherpa> set_filter(1,f)
1
sherpa> WRITE DATA
Write X-Axis: Bin Y-Axis: Flux (Counts)
1 59
2 46
3 49
4 65
5 60
6 60
8 58
...
In this example, data are read into Sherpa, and the
counts amplitude is retrieved using get_data.
A new array a is defined whose elements are the bins for which the
data are greater than 65; the length of this array is 13 (13 bins have
data greater than 65 and are thus to be ignored).
The filter array is then retrieved with get_filter and
the appropriate 13 elements of that array are reset to 0.
The new filter array is then read back into Sherpa,
and we see, e.g., that bin 7 is now ignored.
- sherpa
-
analysis,
get_groups,
ignore,
notice,
set_groups,
set_ignore,
set_ignore2d,
set_ignore_all,
set_ignore_bad,
set_notice,
set_notice2d,
set_notice_all
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