BinWidthAtX.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 AlgorithmFactory, HistogramValidator,\
    MatrixWorkspaceProperty, PythonAlgorithm
from mantid.kernel import Direction
import numpy
import roundinghelper


class BinWidthAtX(PythonAlgorithm):

    _PROP_BIN_WIDTH = 'BinWidth'
    _PROP_INPUT_WS = 'InputWorkspace'
    _PROP_X_VALUE = 'X'

    def category(self):
        '''
        Return algorithm's category.
        '''
        return 'Utility\\Calculation'

    def name(self):
        '''
        Return algorithm's name.
        '''
        return 'BinWidthAtX'

    def summary(self):
        '''
        Return algorithm's summary.
        '''
        return 'Calculates the bin width at X, averaged over all histograms.'

    def version(self):
        '''
        Return algorithm's version.
        '''
        return 1

    def PyInit(self):
        '''
        Declares algorithm's properties.
        '''
        self.declareProperty(
            MatrixWorkspaceProperty(name=self._PROP_INPUT_WS,
                                    defaultValue='',
                                    validator=HistogramValidator(),
                                    direction=Direction.Input),
            doc='A workspace containing the input histograms')
        self.declareProperty(
            name=self._PROP_X_VALUE, defaultValue=0.0,
            direction=Direction.Input, doc='The x value of the bin to use.')
        roundinghelper.declare_rounding_property(self)
        self.declareProperty(
            name=self._PROP_BIN_WIDTH, defaultValue=0.0,
            direction=Direction.Output, doc='The averaged bin width')

    def PyExec(self):
        '''
        Averages the bin widths at X.
        '''
        inputWs = self.getProperty(self._PROP_INPUT_WS).value
        x = self.getProperty(self._PROP_X_VALUE).value
        roundingMode = self.getProperty(
            roundinghelper.PROP_NAME_ROUNDING_MODE).value
        n = inputWs.getNumberHistograms()
        widths = numpy.empty(n)
        for wsIndex in range(n):
            xs = inputWs.readX(wsIndex)
            lowerBound = xs[0]
            upperBound = xs[-1]
            if lowerBound > upperBound:
                lowerBound, upperBound = upperBound, lowerBound
            if x <= lowerBound or x > upperBound:
                raise RuntimeError(self._PROP_X_VALUE + ' = {0} out of range for workspace index {1}'.format(x, wsIndex))
            binIndex = inputWs.yIndexOfX(x, wsIndex)
            dx = xs[binIndex + 1] - xs[binIndex]
            widths[wsIndex] = dx
        binWidth = numpy.mean(widths)
        binWidth = roundinghelper.round(binWidth, roundingMode)
        self.setProperty(self._PROP_BIN_WIDTH, numpy.abs(binWidth))


AlgorithmFactory.subscribe(BinWidthAtX)