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MatchPeaks v1¶

../_images/ImageNotFound.png — Enable screenshots using DOCS_SCREENSHOTS in CMake¶

Summary ¶

Circular shifts (numpy.roll) the data of the input workspace to align peaks without modifying the x-axis.

Properties ¶

Name	Direction	Type	Default	Description
InputWorkspace	Input	MatrixWorkspace	Mandatory	Input workspace
InputWorkspace2	Input	MatrixWorkspace		Input workspace to align peaks with
InputWorkspace3	Input	MatrixWorkspace		Input workspace to align peaks with
MaskBins	Input	boolean	False	Whether to mask shifted bins
MatchInput2ToCenter	Input	boolean	False	Match peaks such that InputWorkspace2 would be centered
OutputWorkspace	Output	MatrixWorkspace	Mandatory	Shifted output workspace
BinRangeTable	Output	TableWorkspace		Table workspace that contains two values defining a range. Bins outside this range are overflown out of range due to circular shiftand can be masked.

This algorithm circular shifts (numpy.roll operation) the Y- and E-values of each spectrum of an input workspace while keeping its X-values. Peak positions of the input workspace can be aligned with the centre of the X-axis as the default option. Optionally, a second input workspace can be given. In this case, the peaks in the first workspace will be aligned to the peaks in the second workspace. If MatchInput2ToCenter option is enabled, first workspace will be rolled according to the difference between the second workspace’s peaks from the center. If the third workspace is given, the first workspace will be shifted according to the difference of peak positions between the second and the third workspaces. A BinRangeTable output contains two values, ‘MinBin’ and ‘MaxBin’. Bins smaller than the ‘MinBin’ value and larger than the ‘MaxBin’ value represent bins that where overflown the x-axis range due to the circular shift. Enabling MaskBins will mask out these bins automatically.

Restrictions ¶

The input workspaces should have one peak (see FindEPP), hence NaN and Inf values will be zeroed, so peak finding can succeed. The peak position is expected to be around the x-axis center, at most quarter of the number of bins away from the center, otherwise no shift will be performed. Furthermore, input workspaces should have the same number of bins and spectra as well as identical x-axes.

Usage ¶

# Create a workspace containing some data.
ws = CreateSampleWorkspace(Function='User Defined',
                           WorkspaceType='Histogram',
                           UserDefinedFunction="name=Gaussian, PeakCentre=3.2, Height=10, Sigma=0.3",
                           NumBanks=1, BankPixelWidth=1,
                           XUnit='DeltaE', XMin=0, XMax=7, BinWidth=0.099)

output_ws = MatchPeaks(InputWorkspace=ws)

print('Peak height at center: {:.11f}'.format(output_ws.readY(0)[ws.blocksize() // 2]))