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CreateWorkspace v1

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Summary

This algorithm constructs a MatrixWorkspace when passed a vector for each of the X, Y, and E data values.

See Also

CreateSingleValuedWorkspace, CreateSampleWorkspace

Properties

Name	Direction	Type	Default	Description
OutputWorkspace	Output	MatrixWorkspace	Mandatory	Name to be given to the created workspace.
DataX	Input	dbl list	Mandatory	X-axis data values for workspace.
DataY	Input	dbl list	Mandatory	Y-axis data values for workspace (measures).
DataE	Input	dbl list		Error values for workspace.
NSpec	Input	number	1	Number of spectra to divide data into.
UnitX	Input	string		The unit to assign to the XAxis
VerticalAxisUnit	Input	string	SpectraNumber	The unit to assign to the second Axis (leave blank for default Spectra number). Allowed values: [‘AtomicDistance’, ‘Degrees’, ‘DeltaE’, ‘DeltaE_inFrequency’, ‘DeltaE_inWavenumber’, ‘dSpacing’, ‘dSpacingPerpendicular’, ‘Empty’, ‘Energy’, ‘Energy_inWavenumber’, ‘Label’, ‘Momentum’, ‘MomentumTransfer’, ‘Phi’, ‘QSquared’, ‘SpinEchoLength’, ‘SpinEchoTime’, ‘Temperature’, ‘Time’, ‘TOF’, ‘Wavelength’, ‘SpectraNumber’, ‘Text’]
VerticalAxisValues	Input	str list		Values for the VerticalAxis.
Distribution	Input	boolean	False	Whether OutputWorkspace should be marked as a distribution.
YUnitLabel	Input	string		Label for Y Axis
WorkspaceTitle	Input	string		Title for Workspace
ParentWorkspace	Input	MatrixWorkspace		Name of a parent workspace.
Dx	Input	dbl list		X error values for workspace (optional).
ParallelStorageMode	Input	string	Parallel::StorageMode::Cloned	The parallel storage mode of the output workspace for MPI builds. Allowed values: [‘Parallel::StorageMode::Cloned’, ‘Parallel::StorageMode::Distributed’, ‘Parallel::StorageMode::MasterOnly’]

Description

This algorithm constructs a MatrixWorkspace when passed a vector for each of the X, Y and optionally E and Dx values. The E values of the output workspace will be zero if not provided. The unit for the X Axis can optionally be specified as any of the units in the Mantid Unit Factory. Multiple spectra may be created by supplying the NSpec Property (integer, default 1). When this is provided the vectors are split into equal-sized spectra (all X, Y, E, Dx values must still be in a single vector for input).

When you use the input property ParentWorkspace, the new workspace is created with the same instrument (including its parameters), sample and run information, and comment field as the parent. The Y units and title are also copied from the parent workspace unless they are provided in the input properties passed to the algorithm.

Note on old behavior regarding spectrum-detector mapping

Until release 3.11 (inclusive) this algorithm created a default (and potentially wrong) mapping from spectra to detectors if no parent workspace was given. This change has no effect if any of the following applies:

• A parent workspace is given.

• No instrument is loaded into to workspace at a later point.

• An instrument is loaded at a later point but LoadInstrument is used with RewriteSpectraMapping=True.

• An instrument is loaded at a later point but LoadInstrument is used with RewriteSpectraMapping=False but a correct mapping is set up before or after loading the instrument.

That is, only the following use is affected:

# See usage example below for setting up input data.
ws = CreateWorkspace(DataX=dataX, DataY=dataY, DataE=dataE, NSpec=4, UnitX="Wavelength")
LoadInstrument(ws, InstrumentName='MARI', RewriteSpectraMap=False)
# None of the spectra in `ws` maps to any detectors since detectors were not known
# at the time of workspace creation. The old behavior used to map spectra 1,2,3,4
# to detector IDs 1,2,3,4. This worked only accidentally if MARI contains detectors
# with IDs 1,2,3,4. Accidental mappings are not a feature anymore.

The solution to this is to set RewriteSpectraMapping=True, set the correct mapping by hand via ws.getSpectrum(i).setDetectorID(id), or use CreateWorkspace with a parent workspace that contains the correct instrument and mapping.

Usage

dataX = [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16]
dataY = [1,2,3,4,5,6,7,8,9,10,11,12]

# The workspace will be named "dataWS1", error values will be zero.
dataWS1 = CreateWorkspace(DataX=dataX, DataY=dataY, NSpec=4, UnitX="Wavelength")

# Create a workspace containing the following error values:
dataE = [1,2,3,4,5,6,7,8,9,10,11,12]
dataWS2 = CreateWorkspace(DataX=dataX, DataY=dataY, DataE=dataE, NSpec=4, UnitX="Wavelength")

# Create a workspace containing Dx values:
dX = [1,2,3,4,5,6,7,8,9,10,11,12]
dataWS3 = CreateWorkspace(DataX=dataX, DataY=dataY, DataE=dataE, NSpec=4, UnitX="Wavelength", Dx=dX)

Categories: AlgorithmIndex | Utility\Workspaces

Source

C++ header: CreateWorkspace.h

C++ source: CreateWorkspace.cpp