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ConvertSpectrumAxis dialog.
Table of Contents
Converts the axis of a Workspace2D which normally holds spectrum numbers to one of Q, Q^2 or theta. ‘Note’: After running this algorithm, some features will be unavailable on the workspace as it will have lost all connection to the instrument. This includes things like the 3D Instrument Display.
| Name | Direction | Type | Default | Description |
|---|---|---|---|---|
| InputWorkspace | Input | MatrixWorkspace | Mandatory | The name of the input workspace. |
| OutputWorkspace | Output | MatrixWorkspace | Mandatory | The name to use for the output workspace. |
| Target | Input | string | Mandatory | The unit to which spectrum axis is converted to - “theta” (for the angle in degrees), Q or Q^2, where elastic Q is evaluated at EFixed. InPlaneTwoTheta and SignedInPlaneTwoTheta are the angle when each point is projected on the horizontal plane.Note that ‘theta’ and ‘signed_theta’ are there for compatibility purposes; they are the same as ‘Theta’ and ‘SignedTheta’ respectively. Allowed values: [‘Theta’, ‘SignedTheta’, ‘InPlaneTwoTheta’, ‘SignedInPlaneTwoTheta’, ‘ElasticQ’, ‘ElasticQSquared’, ‘theta’, ‘signed_theta’, ‘ElasticDSpacing’] |
| EMode | Input | string | Direct | Some unit conversions require this value to be set (“Direct” or “Indirect”). Allowed values: [‘Direct’, ‘Indirect’] |
| EFixed | Input | number | Optional | Value of fixed energy in meV : EI (EMode=Direct) or EF (EMode=Indirect)) |
| OrderAxis | Input | boolean | True | Whether or not to sort the resulting spectrum axis. |
Converts the representation of the vertical axis (the one up the side of a matrix in MantidPlot) of a Workspace2D from its default of holding the spectrum number to the target unit given - theta, elastic Q, elastic Q^2 or elastic d-spacing.
The spectra will be reordered in increasing order by default, however this can be disabled by OrderAxis=False. In the case of the latter, spectra will preserve correspondence to the original workspace. The new unit and duplicates will not be aggregated. Any spectrum for which a detector is not found (i.e. if the instrument definition is incomplete) will not appear in the output workspace.
InPlane2Theta and SignedInPlane2Theta return the 2theta value of the projection of the pixel on the horizontal scattering plane.
Example: Convert vertical axis to theta
# Creates a workspace with some detectors attached
dataws = CreateSampleWorkspace(NumBanks=1,BankPixelWidth=2) # 2x2 detector
theta = ConvertSpectrumAxis(dataws, Target="Theta")
vertical_axis = theta.getAxis(1)
print("There are {} axis values".format(vertical_axis.length()))
print("Final theta value: {:.6f} (degrees)".format(vertical_axis.getValue(vertical_axis.length() - 1)))
There are 4 axis values
Final theta value: 0.129645 (degrees)
Example: Convert vertical axis to elastic Q for direct geometry
# Creates a workspace with some detectors attached
dataws = CreateSampleWorkspace(NumBanks=1,BankPixelWidth=2) # 2x2 detector
qws = ConvertSpectrumAxis(dataws, Target="ElasticQ", EFixed=15., EMode="Direct")
vertical_axis = qws.getAxis(1)
print("There are {} axis values".format(vertical_axis.length()))
print("Final Q value: {:.6f} (A^-1)".format(vertical_axis.getValue(vertical_axis.length() - 1)))
There are 4 axis values
Final Q value: 0.006088 (A^-1)
Categories: AlgorithmIndex | Transforms\Units | Transforms\Axes
C++ header: ConvertSpectrumAxis2.h (last modified: 2020-07-29)
C++ source: ConvertSpectrumAxis2.cpp (last modified: 2020-07-29)