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MaskBins v1

Summary

Marks bins in a workspace as being masked.

See Also

MaskBinsIf, MaskBinsFromTable, MaskNonOverlappingBins

Properties

Name	Direction	Type	Default	Description
InputWorkspace	Input	MatrixWorkspace	Mandatory	The name of the input workspace. Must contain histogram data.
InputWorkspaceIndexType	Input	string		The type of indices in the optional index set; For optimal performance WorkspaceIndex should be preferred;. Allowed values: [‘WorkspaceIndex’]
InputWorkspaceIndexSet	Input	long list		An optional set of spectra that will be processed by the algorithm; If not set, all spectra will be processed; The indices in this list can be workspace indices or possibly spectrum numbers, depending on the selection made for the index type; Indices are entered as a comma-separated list of values, and/or ranges; For example, ‘4,6,10-20,1000’;
OutputWorkspace	Output	MatrixWorkspace	Mandatory	The name of the Workspace containing the masked bins.
XMin	Input	number	Mandatory	The value to start masking from.
XMax	Input	number	Mandatory	The value to end masking at.
SpectraList	Input	long list		Deprecated, use InputWorkspaceIndexSet.

Description

Masks bins in a workspace. Masked bins should properly be regarded as having been completely removed from the workspace. Bins falling within the range given (even partially) are masked, i.e. their data and error values are set to zero and the bin is added to the list of masked bins. This range is masked for all spectra in the workspace (though the workspace does not have to have common X values in all spectra).

At present, although the zeroing of data will obviously be ‘seen’ by all downstream algorithms. Only DiffractionFocussing v2 (version 2) and Q1D v2 have been modified to take account of masking. Several algorithms (e.g. Rebin v1, CropWorkspace v1) have been modified to properly propagate the masking.

Usage

Masking of a small workspace

# Create workspace with 10 bins of width 10
ws = CreateSampleWorkspace(BankPixelWidth=1, Xmax=100, BinWidth=10)

# Mask a range of X-values
wsMasked = MaskBins(ws,XMin=16,XMax=32)

# Show Y values in workspaces
print("Before masking: {}".format(ws.readY(0)))
print("After masking: {}".format(wsMasked.readY(0)))

Output:

Before masking: [  0.3   0.3   0.3   0.3   0.3  10.3   0.3   0.3   0.3   0.3]
After masking: [  0.3   0.    0.    0.    0.3  10.3   0.3   0.3   0.3   0.3]

Related Algorithms

RemoveBins

RemoveBins v1 can work in several ways, if the bins are at the edges of the workspace they will be removed, and that will in many ways act like Masking the bins. If the bins are in the middle of the workspace then the effect depends on the type of interpolation, but importantly these bins will continue to influence future algorithms as opposed to masked bins. For example, with no interpolation RemoveBins v1 sets the bin values to 0. This 0 values will be included in the summing performed in DiffractionFocussing, pushing down the values in that region. MaskBins is more clever. While if you look at the data, it will appear that it has simply set the values to 0. It has also set a series of flags inside that mark those bins to not be included in further claculations. This means that when you Focus the data these values are simply missed out of the summing that is performed.

Categories: AlgorithmIndex | Transforms\Masking

Source

C++ header: MaskBins.h

C++ source: MaskBins.cpp