HFIRSANS2Wavelength.py

# Mantid Repository : https://github.com/mantidproject/mantid
#
# Copyright © 2018 ISIS Rutherford Appleton Laboratory UKRI,
#   NScD Oak Ridge National Laboratory, European Spallation Source,
#   Institut Laue - Langevin & CSNS, Institute of High Energy Physics, CAS
# SPDX - License - Identifier: GPL - 3.0 +
from mantid.api import (PythonAlgorithm, AlgorithmFactory, MatrixWorkspaceProperty, PropertyMode, Progress)
from mantid.kernel import (Direction)


class HFIRSANS2Wavelength(PythonAlgorithm):

    def category(self):
        return 'SANS\\Wavelength'

    def summary(self):
        return 'Convert the fake time of flight event workspace into a Workspace2D with units of wavelength'

    def PyInit(self):
        # Workspace which is to be masked
        self.declareProperty(MatrixWorkspaceProperty("InputWorkspace", '',
                                                     optional=PropertyMode.Mandatory, direction=Direction.Input),
                             doc='The workspace which is to be converted to wavelength')
        self.declareProperty(MatrixWorkspaceProperty('OutputWorkspace', '',
                                                     optional=PropertyMode.Mandatory, direction=Direction.Output),
                             doc='The output workspace.')

    def PyExec(self):
        inWS = self.getProperty("InputWorkspace").value
        runObj = inWS.getRun()
        try:
            wavelength = runObj['wavelength'].getStatistics().mean
            wavelength_spread = runObj['wavelength_spread'].getStatistics().mean
            wavelength_spread *= wavelength
        except:
            raise ValueError("Could not read wavelength and wavelength_spread logs from the workspace")
        progress = Progress(self, 0.0, 1.0, 4)

        # rebin into a single bin
        progress.report('Rebin')
        rebin_alg = self.createChildAlgorithm("Rebin", enableLogging=False)
        rebin_alg.setProperty('InputWorkspace', inWS)
        rebin_alg.setProperty('Params', '-20000,40000,20000')
        rebin_alg.setProperty('PreserveEvents', False)
        rebin_alg.execute()
        outWS = rebin_alg.getProperty("OutputWorkspace").value

        # scale to wavelength spread
        progress.report('Scale to spread')
        scale_alg = self.createChildAlgorithm("ScaleX", enableLogging=False)
        scale_alg.setProperty('InputWorkspace', outWS)
        scale_alg.setProperty('OutputWorkspace', outWS)
        scale_alg.setProperty('Factor', wavelength_spread / 40000.)
        scale_alg.execute()
        outWS = scale_alg.getProperty("OutputWorkspace").value

        # shift to wavelength center
        progress.report('Shift to wavelength center')
        scale_alg = self.createChildAlgorithm("ScaleX", enableLogging=False)
        scale_alg.setProperty('InputWorkspace', outWS)
        scale_alg.setProperty('OutputWorkspace', outWS)
        scale_alg.setProperty('Factor', wavelength)
        scale_alg.setProperty('Operation', 'Add')
        scale_alg.execute()
        outWS = scale_alg.getProperty("OutputWorkspace").value

        # change units
        progress.report('Set units')
        outWS.getAxis(0).setUnit('Wavelength')
        self.setProperty("OutputWorkspace", outWS)


AlgorithmFactory.subscribe(HFIRSANS2Wavelength)