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Exercise 3 Solutions

The aim of this exercise is to write a small algorithm that wraps a small script that focuses some powder diffraction data.

# Write an algorithm called PowerDiffractionReduce
#  - The algorithm should have 3 properties:
#  - Filename: A FileProperty for a TOF data file to load (ignore extensions)
#  - CalFilename: A FileProperty for a cal file (ignore extensions)
#  - OutputWorkspace: An output WorkspaceProperty to hold the final result.


# The steps the algorithm should perform are
#  - Use the Load algorithm to load the TOF data
#  - Apply the calibration file using ApplyDiffCalc
#  - Run ConvertUnits on the TOF data to convert to dSpacing
#  - Run DiffractionFocusing on the previous output & focus the data using the same cal file from the earlier step
#   (called a grouping file here)
#  - Set the output from the DiffractionFocussing algorithm as the output of PowerDiffractionReduce.
#  - Delete the temporary reference using DeleteWorkspace


# To test the algorithm, execute the script that contains the algorithm to register it with Mantid. It will then
# show up in the list of algorithms. Use the following inputs:
#  - Filename: HRP39182.RAW
#  - CalFilename: hrpd_new_072_01_corr.cal
#  - OutputWorkspace: focussed

from mantid.kernel import *
from mantid.api import *

# Class definition
class DiffractionPowderReduce(PythonAlgorithm):

    def category(self):
        return "Examples"

    def PyInit(self):
        # 2 input properties
        self.declareProperty(FileProperty(name="Filename", defaultValue="", action=FileAction.Load),
                             doc="TOF data filename")
        self.declareProperty(FileProperty(name="CalFilename", defaultValue="", action=FileAction.Load),
                             doc="TOF data filename")

        # 1 Output property
        self.declareProperty(WorkspaceProperty(name="OutputWorkspace", defaultValue="",
                                               direction=Direction.Output))

    def PyExec(self):
        from mantid.simpleapi import Load, ApplyDiffCal, ConvertUnits, DiffractionFocussing, DeleteWorkspace

        # Load file to workspace
        _tmpws = Load(Filename=self.getPropertyValue("Filename"))

        # Apply Calibration and Convert Units
        calfile = self.getProperty("CalFilename").value
        ApplyDiffCal(InstrumentWorkspace=_tmpws, CalibrationFile=calfile)
        _tmpws = ConvertUnits(InputWorkspace=_tmpws, Target="dSpacing")

        # Focus
        _tmpws = DiffractionFocussing(InputWorkspace=_tmpws, GroupingFileName=calfile)

        # Store reference after algorithm has gone
        self.setProperty("OutputWorkspace", _tmpws)

        DeleteWorkspace(_tmpws)

# Register algorithm with Mantid
AlgorithmFactory.subscribe(DiffractionPowderReduce)