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GroupDetectors v1

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Summary

Sums spectra bin-by-bin, equivalent to grouping the data from a set of detectors. Individual groups can be specified by passing the algorithm a list of spectrum numbers, detector IDs or workspace indices. Many spectra groups can be created in one execution via an input file.

Properties

Name	Direction	Type	Default	Description
Workspace	InOut	MatrixWorkspace	Mandatory	The name of the workspace2D on which to perform the algorithm
SpectraList	Input	int list		An array containing a list of the indexes of the spectra to combine (DetectorList and WorkspaceIndexList are ignored if this is set)
DetectorList	Input	int list		An array of detector ID’s (WorkspaceIndexList is ignored if this is set)
WorkspaceIndexList	Input	unsigned int list		An array of workspace indices to combine
ResultIndex	Output	number		The workspace index of the summed spectrum (or -1 on error)

Description

This algorithm sums, bin-by-bin, multiple spectra into a single spectra. The errors are summed in quadrature and the algorithm checks that the bin boundaries in X are the same. The new summed spectra are created at the start of the output workspace and have workspace index numbers that start at zero and increase in the order the groups are specified. Each new group takes the spectra number from the first input spectrum specified for that group. All detectors from the grouped spectra will be moved to belong to the new spectrum.

Not all spectra in the input workspace have to be copied to a group. If KeepUngroupedSpectra is set to true any spectra not listed will be copied to the output workspace after the groups in order. If KeepUngroupedSpectra is set to false only the spectra selected to be in a group will be used.

To create a single group the list of spectra can be identified using a list of either spectrum numbers, detector IDs or workspace indices. The list should be set against the appropriate property.

An input file allows the specification of many groups. The file must have the following format* (extra space and comments starting with # are allowed):

"unused number1"
"unused number2"
"number_of_input_spectra1"
"input spec1" "input spec2" "input spec3" "input spec4"
"input spec5 input spec6"
**
"unused number2"
"number_of_input_spectra2"
"input spec1" "input spec2" "input spec3" "input spec4"

* each phrase in “” is replaced by a single integer

** the section of the file that follows is repeated once for each group

Some programs require that “unused number1” is the number of groups specified in the file but Mantid ignores that number and all groups contained in the file are read regardless. “unused number2” is in other implementations the group’s spectrum number but in this algorithm it is is ignored and can be any integer (not necessarily the same integer)

An example of an input file follows:

2
1
64
1 2 3 4 5 6 7 8 9 10
11 12 13 14 15 16 17 18 19 20
21 22 23 24 25 26 27 28 29 30
31 32 33 34 35 36 37 38 39 40
41 42 43 44 45 46 47 48 49 50
51 52 53 54 55 56 57 58 59 60
61 62 63 64
2
60
65 66 67 68 69 70 71 72 73 74
75 76 77 78 79 80 81 82 83 84
85 86 87 88 89 90 91 92 93 94
95 96 97 98 99 100 101 102 103 104
105 106 107 108 109 110 111 112 113 114
115 116 117 118 119 120 121 122 123 124

In addition the following XML grouping format is also supported

<?xml version="1.0" encoding="UTF-8" ?>
<detector-grouping>
  <group name="fwd1"> <ids val="1-32"/> </group>
  <group name="bwd1"> <ids val="33,36,38,60-64"/> </group>

  <group name="fwd2"><detids val="1,2,17,32"/></group>
  <group name="bwd2"><detids val="33,36,38,60,64"/> </group>
</detector-grouping>

where is used to specify spectra IDs and detector IDs.

Usage

Note

To run these usage examples please first download the usage data, and add these to your path. In Mantid this is done using Manage User Directories.

Example 1: specifying spectrum numbers

# Create a workspace filled with a constant value = 0.3
ws=CreateSampleWorkspace()
# Group detectors using a list of spectrum numbers
group_index = GroupDetectors(ws,SpectraList=[1,3,5],Version=1)

# The specified spectra are grouped and saved into the same workspace.
# The returned value is an index in ws which contains the created group.

# Check the result
print('The workspace still has {} spectra'.format(ws.getNumberHistograms()))
print('The group is in the {} -th spectrum'.format(group_index))

# Get detector IDs in the group
grp_ids = ws.getSpectrum(0).getDetectorIDs()
print('Number of grouped detectors is {}'.format(len(grp_ids)))
print('Detector IDs: {}'.format(grp_ids))

# The other 2 spectra that were included in the group contain no data
grp_ids = ws.getSpectrum(2).getDetectorIDs()
print('Number of detectors is {}'.format(len(grp_ids)))
grp_ids = ws.getSpectrum(4).getDetectorIDs()
print('Number of detectors is {}'.format(len(grp_ids)))

# The rest of the spectra are unchanged
grp_ids = ws.getSpectrum(1).getDetectorIDs()
print('Number of detectors is {}'.format(len(grp_ids)))
grp_ids = ws.getSpectrum(3).getDetectorIDs()
print('Number of detectors is {}'.format(len(grp_ids)))
grp_ids = ws.getSpectrum(5).getDetectorIDs()
print('Number of detectors is {}'.format(len(grp_ids)))
print('...')
grp_ids = ws.getSpectrum(199).getDetectorIDs()
print('Number of detectors is {}'.format(len(grp_ids)))

Output

The workspace still has 200 spectra
The group is in the 0 -th spectrum
Number of grouped detectors is 3
Detector IDs: set(100,102,104)
Number of detectors is 0
Number of detectors is 0
Number of detectors is 1
Number of detectors is 1
Number of detectors is 1
...
Number of detectors is 1

Example 2: specifying detctor IDs

# Create a workspace filled with a constant value = 0.3
ws=CreateSampleWorkspace()
# Group detectots using a list of detctor IDs
group_index = GroupDetectors(ws,DetectorList=[100,102,104],Version=1)

# The specified spectra are grouped and saved into the same workspace.
# The returned value is an index in ws which contains the created group.

# Check the result
print('The workspace still has {} spectra'.format(ws.getNumberHistograms()))
print('The group is in the {} -th spectrum'.format(group_index))


# Get detector IDs in the group
grp_ids = ws.getSpectrum(0).getDetectorIDs()
print ('Number of grouped detectors is {}'.format(len(grp_ids)))
print ('Detector IDs: {}'.format(grp_ids))

# The other 2 spectra that were included in the group contain no data
grp_ids = ws.getSpectrum(2).getDetectorIDs()
print ('Number of detectors is {}'.format(len(grp_ids)))
grp_ids = ws.getSpectrum(4).getDetectorIDs()
print ('Number of detectors is {}'.format(len(grp_ids)))

# The rest of the spectra are unchanged
grp_ids = ws.getSpectrum(1).getDetectorIDs()
print ('Number of detectors is {}'.format(len(grp_ids)))
grp_ids = ws.getSpectrum(3).getDetectorIDs()
print ('Number of detectors is {}'.format(len(grp_ids)))
grp_ids = ws.getSpectrum(5).getDetectorIDs()
print ('Number of detectors is {}'.format(len(grp_ids)))
print ('...')
grp_ids = ws.getSpectrum(199).getDetectorIDs()
print ('Number of detectors is {}'.format(len(grp_ids)))

Output

The workspace still has 200 spectra
The group is in the 0 -th spectrum
Number of grouped detectors is 3
Detector IDs: set(100,102,104)
Number of detectors is 0
Number of detectors is 0
Number of detectors is 1
Number of detectors is 1
Number of detectors is 1
...
Number of detectors is 1

Example 3: specifying workspace indices

# Create a workspace filled with a constant value = 0.3
ws=CreateSampleWorkspace()
# Group detectots using a list of workspace indices
group_index = GroupDetectors(ws,WorkspaceIndexList=[0,2,4],Version=1)

# The specified spectra are grouped and saved into the same workspace.
# The returned value is an index in ws which contains the created group.

# Check the result
print('The workspace still has {} spectra'.format(ws.getNumberHistograms()))
print('The group is in the {} -th spectrum'.format(group_index))


# Get detector IDs in the group
grp_ids = ws.getSpectrum(0).getDetectorIDs()
print ('Number of grouped detectors is {}'.format(len(grp_ids)))
print ('Detector IDs: {}'.format(grp_ids))

# The other 2 spectra that were included in the group contain no data
grp_ids = ws.getSpectrum(2).getDetectorIDs()
print ('Number of detectors is {}'.format(len(grp_ids)))
grp_ids = ws.getSpectrum(4).getDetectorIDs()
print ('Number of detectors is {}'.format(len(grp_ids)))

# The rest of the spectra are unchanged
grp_ids = ws.getSpectrum(1).getDetectorIDs()
print ('Number of detectors is {}'.format(len(grp_ids)))
grp_ids = ws.getSpectrum(3).getDetectorIDs()
print ('Number of detectors is {}'.format(len(grp_ids)))
grp_ids = ws.getSpectrum(5).getDetectorIDs()
print ('Number of detectors is {}'.format(len(grp_ids)))
print ('...')
grp_ids = ws.getSpectrum(199).getDetectorIDs()
print ('Number of detectors is {}'.format(len(grp_ids)))

Output

The workspace still has 200 spectra
The group is in the 0 -th spectrum
Number of grouped detectors is 3
Detector IDs: set(100,102,104)
Number of detectors is 0
Number of detectors is 0
Number of detectors is 1
Number of detectors is 1
Number of detectors is 1
...
Number of detectors is 1

Categories: AlgorithmIndex | Transforms\Grouping

Source

C++ header: GroupDetectors.h

C++ source: GroupDetectors.cpp