EqualBinsChecker.cpp

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// 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 +
#include "MantidKernel/EqualBinsChecker.h"
#include "MantidKernel/Logger.h"
#include <cmath>
#include <ostream>
#include <sstream>
#include <stdexcept>
#include <vector>
 
namespace {
// Initialize the logger
Mantid::Kernel::Logger g_log("EqualBinsChecker");
} // namespace
 
namespace Mantid::Kernel {
 
EqualBinsChecker::EqualBinsChecker(const MantidVec &xData, const double errorLevel, const double warningLevel)
    : m_xData(xData), m_errorLevel(errorLevel), m_warn(warningLevel > 0), m_warningLevel(warningLevel),
      m_refBinType(ReferenceBin::Average), m_errorType(ErrorType::Cumulative) {}
 
void EqualBinsChecker::setReferenceBin(const ReferenceBin &refBinType) { m_refBinType = refBinType; }
 
void EqualBinsChecker::setErrorType(const ErrorType &errorType) { m_errorType = errorType; }
 
std::string EqualBinsChecker::validate() const {
  const auto &xData = m_xData;
  const auto xSize = xData.size();
  // First check for empty input
  if (xSize == 0) {
    return "Input workspace must not be empty";
  }
 
  // reference bin width to compare to
  const double dx = getReferenceDx();
 
  // Check each width against dx
  bool printWarning = false;
  for (size_t bin = 0; bin < xSize - 2; bin++) {
    const double diff = getDifference(bin, dx);
    if (diff > m_errorLevel) {
      std::stringstream errorStr;
      errorStr << "X axis must be linear (all bins must have the same width) ";
      errorStr << "dx=" << xData[bin + 1] - xData[bin] << " reference dx=" << dx << " bin number=" << bin;
      return errorStr.str();
    } else if (m_warn && diff > m_warningLevel) {
      // just warn the user
      printWarning = true;
    }
  }
 
  if (printWarning) {
    g_log.warning() << "Bin widths differ by more than " << m_warningLevel * 100 << "% of average." << std::endl;
  }
 
  return std::string();
}
 
double EqualBinsChecker::getReferenceDx() const {
  if (m_xData.size() < 2) {
    throw std::runtime_error("No bins in input X data");
  }
 
  if (m_refBinType == ReferenceBin::Average) {
    // average bin width
    const auto xSize = m_xData.size();
    return (m_xData[xSize - 1] - m_xData[0]) / static_cast<double>(xSize - 1);
  } else {
    // first bin width
    return m_xData[1] - m_xData[0];
  }
}
 
double EqualBinsChecker::getDifference(const size_t bin, const double dx) const {
  if (bin > m_xData.size() - 2) {
    throw std::invalid_argument("Not enough bins in input X data");
  }
 
  if (m_errorType == ErrorType::Individual) {
    return std::fabs(dx - m_xData[bin + 1] + m_xData[bin]) / dx;
  } else {
    // cumulative errors
    return std::fabs((m_xData[bin + 1] - m_xData[0] - static_cast<double>(bin + 1) * dx) / dx);
  }
}
 
} // namespace Mantid::Kernel