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PeaksOnSurface v1

Summary

Find peaks intersecting a single surface region.

See Also

PeaksInRegion

Properties

Name	Direction	Type	Default	Description
InputWorkspace	Input	PeaksWorkspace	Mandatory	An input peaks workspace.
CoordinateFrame	Input	string	Mandatory	What coordinate system to use for intersection criteria? DetectorSpace: Real-space coordinates. Q (lab frame): Wave-vector change of the lattice in the lab frame. Q (sample frame): Momentum in the sample frame. HKL. Allowed values: [‘Detector space’, ‘Q (lab frame)’, ‘Q (sample frame)’, ‘HKL’]
PeakRadius	Input	number	0	Effective peak radius in CoordinateFrame
OutputWorkspace	Output	TableWorkspace	Mandatory	An output table workspace. Two columns. Peak index into input workspace, and boolean, where true is for positive intersection.
Vertex1	Input	dbl list	Mandatory	A comma separated list of cartesian coordinates for the lower left vertex of the surface. Values to be specified in the CoordinateFrame choosen.
Vertex2	Input	dbl list	Mandatory	A comma separated list of cartesian coordinates for the upper left vertex of the surface. Values to be specified in the CoordinateFrame choosen.
Vertex3	Input	dbl list	Mandatory	A comma separated list of cartesian coordinates for the upper right vertex of the surface. Values to be specified in the CoordinateFrame choosen.
Vertex4	Input	dbl list	Mandatory	A comma separated list of cartesian coordinates for the lower right vertex of the surface. Values to be specified in the CoordinateFrame choosen.

Description

Determine whether a peak intersects a surface. Similar to PeaksInRegion v1. The vertexes of the surface must be provided. The vertexes must be provided in clockwise ordering starting at the lower left.

Usage

Example - Peaks on and off a finite surface

# Load an MDEventWorkspace (QLab) containing some SC diffration peaks
mdew = Load("TOPAZ_3680_5_sec_MDEW.nxs")
# Find some peaks. These are all unindexed so will have HKL = [0,0,0]
peaks = FindPeaksMD(InputWorkspace=mdew, MaxPeaks=1)

# Peak is on the plane
out_of_plane_offset = 0
tbl = PeaksOnSurface(InputWorkspace=peaks, PeakRadius=1.0, CoordinateFrame='HKL',
                     Vertex1=[1.0, -1.0, out_of_plane_offset], Vertex2=[-1.0,-1.0,out_of_plane_offset],
                     Vertex3=[-1.0, 1.0,out_of_plane_offset], Vertex4=[1.0, 1.0,out_of_plane_offset])
print("{{'Distance': {Distance}, 'PeakIndex': {PeakIndex}, 'Intersecting': {Intersecting}}}".format(**tbl.row(0)))

# Peak is off the plane, and does not intesect it
out_of_plane_offset = 1.000
tbl = PeaksOnSurface(InputWorkspace=peaks, PeakRadius=0.999,  CoordinateFrame='HKL',
                     Vertex1=[1.0, -1.0, out_of_plane_offset], Vertex2=[-1.0,-1.0,out_of_plane_offset],
                     Vertex3=[-1.0, 1.0,out_of_plane_offset], Vertex4=[1.0, 1.0,out_of_plane_offset])
print("{{'Distance': {Distance}, 'PeakIndex': {PeakIndex}, 'Intersecting': {Intersecting}}}".format(**tbl.row(0)))

# Peak is off the plane, but does intesect it when radius is made larger
tbl = PeaksOnSurface(InputWorkspace=peaks, PeakRadius=1.000,  CoordinateFrame='HKL',
                     Vertex1=[1.0, -1.0, out_of_plane_offset], Vertex2=[-1.0,-1.0,out_of_plane_offset],
                     Vertex3=[-1.0, 1.0,out_of_plane_offset], Vertex4=[1.0, 1.0,out_of_plane_offset])
print("{{'Distance': {Distance}, 'PeakIndex': {PeakIndex}, 'Intersecting': {Intersecting}}}".format(**tbl.row(0)))

Output:

{'Distance': 0.0, 'PeakIndex': 0, 'Intersecting': True}
{'Distance': -1.0, 'PeakIndex': 0, 'Intersecting': False}
{'Distance': -1.0, 'PeakIndex': 0, 'Intersecting': True}

Categories: AlgorithmIndex | Crystal\Peaks

Source

C++ header: PeaksOnSurface.h

C++ source: PeaksOnSurface.cpp