LoadHFIRSANS.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 "MantidDataHandling/LoadHFIRSANS.h"
#include "MantidAPI/AlgorithmFactory.h"
#include "MantidAPI/Axis.h"
#include "MantidAPI/FileProperty.h"
#include "MantidAPI/RegisterFileLoader.h"
#include "MantidAPI/Run.h"
#include "MantidAPI/WorkspaceFactory.h"
#include "MantidDataHandling/XmlHandler.h"
#include "MantidDataObjects/Workspace2D.h"
#include "MantidGeometry/Instrument.h"
#include "MantidKernel/BoundedValidator.h"
#include "MantidKernel/ConfigService.h"
#include "MantidKernel/OptionalBool.h"
#include "MantidKernel/Strings.h"
#include "MantidKernel/TimeSeriesProperty.h"
#include "MantidKernel/UnitFactory.h"
 
#include <boost/algorithm/string/split.hpp>
#include <boost/algorithm/string/trim.hpp>
#include <boost/lexical_cast.hpp>
#include <boost/regex.hpp>
#include <memory>
 
#include <MantidKernel/StringTokenizer.h>
#include <Poco/DOM/DOMParser.h>
#include <Poco/DOM/Document.h>
#include <Poco/DOM/Element.h>
#include <Poco/DOM/Node.h>
#include <Poco/DOM/NodeList.h>
#include <Poco/DOM/Text.h>
#include <Poco/Path.h>
#include <Poco/SAX/InputSource.h>
 
#include <algorithm>
#include <cmath>
#include <iostream>
#include <limits>
#include <memory>
#include <sstream>
#include <string>
#include <utility>
#include <vector>
 
namespace Mantid::DataHandling {
 
using Mantid::API::WorkspaceProperty;
using Mantid::Kernel::Direction;
using Types::Core::DateAndTime;
using namespace Kernel;
using namespace API;
using namespace Geometry;
using namespace DataObjects;
 
// Register the algorithm into the AlgorithmFactory
DECLARE_FILELOADER_ALGORITHM(LoadHFIRSANS)
 
 
int LoadHFIRSANS::confidence(Kernel::FileDescriptor &descriptor) const {
  if (descriptor.extension() != ".xml")
    return 0;
 
  std::istream &is = descriptor.data();
  int confidence(0);
 
  { // start of inner scope
    Poco::XML::InputSource src(is);
    // Set up the DOM parser and parse xml file
    Poco::XML::DOMParser pParser;
    Poco::AutoPtr<Poco::XML::Document> pDoc;
    try {
      pDoc = pParser.parse(&src);
    } catch (Poco::Exception &e) {
      throw Kernel::Exception::FileError("Unable to parse File (" + descriptor.filename() + ")", e.displayText());
    } catch (...) {
      throw Kernel::Exception::FileError("Unable to parse File:", descriptor.filename());
    }
    // Get pointer to root element
    Poco::XML::Element *pRootElem = pDoc->documentElement();
    if (pRootElem) {
      if (pRootElem->tagName() == "SPICErack") {
        confidence = 80;
      }
    }
  } // end of inner scope
 
  return confidence;
}
 
void LoadHFIRSANS::init() {
  declareProperty(std::make_unique<API::FileProperty>("Filename", "", API::FileProperty::Load, ".xml"),
                  "The name of the input xml file to load");
  declareProperty(
      std::make_unique<API::WorkspaceProperty<API::Workspace>>("OutputWorkspace", "", Kernel::Direction::Output),
      "The name of the Output workspace");
 
  // Optionally, we can specify the wavelength and wavelength spread and
  // overwrite the value in the data file (used when the data file is not
  // populated)
  auto mustBePositive = std::make_shared<Kernel::BoundedValidator<double>>();
  mustBePositive->setLower(0.0);
  declareProperty("Wavelength", EMPTY_DBL(), mustBePositive,
                  "Optional wavelength value to use when loading the data file "
                  "(Angstrom). This value will be used instead of the value "
                  "found in the data file.");
  declareProperty("WavelengthSpread", EMPTY_DBL(), mustBePositive,
                  "Optional wavelength spread value to use when loading the "
                  "data file (Angstrom). This value will be used instead of "
                  "the value found in the data file.");
  declareProperty("SampleDetectorDistance", EMPTY_DBL(),
                  "Sample to detector distance to use (overrides meta data), in mm");
}
 
/*******************************************************************************
 * Main method.
 */
void LoadHFIRSANS::exec() {
 
  // Parse the XML metadata
  setInputFileAsHandler();
  setTimes();
  setWavelength();
  createWorkspace();
  storeMetaDataIntoWS();
  // ugly hack for Biosans wing detector:
  // it tests if there is metadata tagged with the wing detector
  // if so, puts the detector in the right angle
  if (m_metadata.find("Motor_Positions/det_west_wing_rot") != m_metadata.end()) {
    rotateDetector();
  }
  moveDetector();
  runLoadInstrument();
  // This needs parameters from IDF! Run load instrument before!
  setBeamDiameter();
  setProperty("OutputWorkspace", m_workspace);
}
 
void LoadHFIRSANS::setInputFileAsHandler() {
  // Set up the XmlHandler handler and parse xml file
  std::string fileName = getPropertyValue("Filename");
  try {
    m_xmlHandler = XmlHandler(fileName);
  } catch (...) {
    throw Kernel::Exception::FileError("Unable to parse File:", fileName);
  }
  m_metadata = m_xmlHandler.get_metadata(m_tags_to_ignore);
  setSansSpiceXmlFormatVersion();
}
 
/***
 * 2016/11/09 : There is a new tag sans_spice_xml_format_version in the XML
 * It identifies changes in the XML format.
 * Useful to test tags rather than using the date.
 * @param metadata
 */
void LoadHFIRSANS::setSansSpiceXmlFormatVersion() {
 
  if (m_metadata.find("Header/sans_spice_xml_format_version") != m_metadata.end()) {
    m_sansSpiceXmlFormatVersion = boost::lexical_cast<double>(m_metadata["Header/sans_spice_xml_format_version"]);
  }
  g_log.debug() << "Sans_spice_xml_format_version == " << m_sansSpiceXmlFormatVersion << "\n";
}
 
void LoadHFIRSANS::setTimes() {
  // start_time
  std::map<std::string, std::string> attributes = m_xmlHandler.get_attributes_from_tag("/");
 
  m_startTime = DateAndTime(attributes["start_time"]);
  m_endTime = DateAndTime(attributes["end_time"]);
}
 
void LoadHFIRSANS::setWavelength() {
 
  double wavelength_input = getProperty("Wavelength");
  double wavelength_spread_input = getProperty("WavelengthSpread");
 
  if (isEmpty(wavelength_input)) {
    m_wavelength = boost::lexical_cast<double>(m_metadata["Header/wavelength"]);
  } else {
    m_wavelength = wavelength_input;
  }
 
  if (isEmpty(wavelength_spread_input)) {
    m_dwavelength = boost::lexical_cast<double>(m_metadata["Header/wavelength_spread"]);
    // 20160720: New wavelength will be a ratio
    // UGLY HACK! Comparing dates...
    DateAndTime changingDate("2016-06-13 00:00:00");
    if (m_startTime >= changingDate) {
      g_log.debug() << "Using wavelength spread as a ratio..." << '\n';
      m_dwavelength = m_wavelength * m_dwavelength;
    }
  } else {
    m_dwavelength = wavelength_spread_input;
  }
 
  g_log.debug() << "Final Wavelength: " << m_wavelength << " :: Wavelength Spread: " << m_dwavelength << '\n';
}
 
std::pair<int, int> LoadHFIRSANS::parseDetectorDimensions(const std::string &dims_str) {
 
  // Read in the detector dimensions from the Detector tag
 
  std::pair<int, int> dims = std::make_pair(0, 0);
 
  boost::regex b_re_sig(R"(INT\d+\[(\d+),(\d+)\])");
  if (boost::regex_match(dims_str, b_re_sig)) {
    boost::match_results<std::string::const_iterator> match;
    boost::regex_search(dims_str, match, b_re_sig);
    // match[0] is the full string
    Kernel::Strings::convert(match[1], dims.first);
    Kernel::Strings::convert(match[2], dims.second);
  }
  if (dims.first == 0 || dims.second == 0)
    g_log.notice() << "Could not read in the number of pixels!" << '\n';
  return dims;
}
 
std::vector<int> LoadHFIRSANS::readData(const std::string &dataXpath) {
 
  // data container
  std::vector<int> data;
  unsigned int totalDataSize = 0;
 
  // let's see how many detectors we have
  std::vector<std::string> detectors = m_xmlHandler.get_subnodes(dataXpath);
  g_log.debug() << "Number the detectors found in Xpath " << dataXpath << " = " << detectors.size() << '\n';
 
  // iterate every detector in the xml file
  for (const auto &detector : detectors) {
    std::string detectorXpath = std::string(dataXpath).append("/").append(detector);
    // type : INT32[192,256]
    std::map<std::string, std::string> attributes = m_xmlHandler.get_attributes_from_tag(detectorXpath);
    std::pair<int, int> dims = parseDetectorDimensions(attributes["type"]);
 
    // Horrible hack:
    // Some old files had a: //Data/DetectorWing with dimensions:
    // 16 x 256 = 4096. This must be ignored as it is not in the IDF
    // The real wing detector is larger than that
    if (detectorXpath.find("DetectorWing") != std::string::npos && dims.first * dims.second <= 4096)
      break;
 
    totalDataSize += dims.first * dims.second;
    g_log.debug() << "Parsing detector XPath " << detectorXpath << " with dimensions: " << dims.first << " x "
                  << dims.second << " = " << dims.first * dims.second << '\n';
 
    std::string data_str = m_xmlHandler.get_text_from_tag(detectorXpath);
    g_log.debug() << "The size of detector contents (xpath = " << detectorXpath << ") is " << data_str.size()
                  << " bytes." << '\n';
 
    // convert string data into a vector<int>
    std::stringstream iss(data_str);
    double number;
    while (iss >> number) {
      data.emplace_back(static_cast<int>(number));
    }
    g_log.debug() << "Detector XPath: " << detectorXpath
                  << " parsed. Total size of data processed up to now = " << data.size() << " from a total of "
                  << totalDataSize << '\n';
  }
 
  if (data.size() != totalDataSize) {
    g_log.error() << "Total data size = " << totalDataSize << ". Parsed data size = " << data.size() << '\n';
    throw Kernel::Exception::NotImplementedError("Inconsistent data set: There were more data pixels found than "
                                                 "declared in the Spice XML meta-data.");
  }
  return data;
}
 
void LoadHFIRSANS::permuteTubes(std::vector<int> &data) {
  const std::string &instrumentName = m_metadata["Header/Instrument"];
 
  if (instrumentName.compare("CG2") == 0 || instrumentName.compare("GPSANS") == 0) {
    std::vector<int> temp(data.size());
    size_t nTubes(std::stoul(m_metadata["Header/Number_of_X_Pixels"]));
    size_t nEightPacks = nTubes / 8;
    size_t nPixelPerTube(std::stoul(m_metadata["Header/Number_of_Y_Pixels"]));
    // permutation that takes us from a tube ID in the IDF to a tube ID in the
    // XML file
    std::vector<size_t> perm{0, 2, 4, 6, 1, 3, 5, 7};
    size_t newStartPixelID, oldStartPixelID;
    for (size_t e = 0; e < nEightPacks; ++e) {               // iterate over all eightpacks
      for (size_t t = 0; t < 8; t++) {                       // iterate over each tube in an eightpack
        newStartPixelID = (t + 8 * e) * nPixelPerTube;       // t+8*e is the new tube ID
        oldStartPixelID = (perm[t] + 8 * e) * nPixelPerTube; // perm[t]+8*e is the old tube ID
        for (size_t p = 0; p < nPixelPerTube; p++) {         // copy the "contents of the tube"
          temp[p + newStartPixelID] = data[p + oldStartPixelID];
        }
      }
    }
    for (size_t i = 0; i < data.size(); i++) {
      data[i] = temp[i];
    }
  }
}
 
void LoadHFIRSANS::storeValue(int specID, double value, double error, double wavelength, double dwavelength) {
  auto &X = m_workspace->mutableX(specID);
  auto &Y = m_workspace->mutableY(specID);
  auto &E = m_workspace->mutableE(specID);
  // The following is mostly to make Mantid happy by defining a histogram with
  // a single bin around the neutron wavelength
  X[0] = wavelength - dwavelength / 2.0;
  X[1] = wavelength + dwavelength / 2.0;
  Y[0] = value;
  E[0] = error;
  m_workspace->getSpectrum(specID).setSpectrumNo(specID);
}
 
void LoadHFIRSANS::createWorkspace() {
 
  std::vector<int> data = readData("//Data");
  permuteTubes(data);
 
  int numSpectra = static_cast<int>(data.size()) + m_nMonitors;
 
  m_workspace = std::dynamic_pointer_cast<DataObjects::Workspace2D>(
      API::WorkspaceFactory::Instance().create("Workspace2D", numSpectra, 2, 1));
  m_workspace->setTitle(m_metadata["Header/Scan_Title"]);
  m_workspace->getAxis(0)->unit() = Kernel::UnitFactory::Instance().create("Wavelength");
  m_workspace->setYUnit("Counts");
 
  auto monitorCounts = boost::lexical_cast<double>(m_metadata["Counters/monitor"]);
  auto countingTime = boost::lexical_cast<double>(m_metadata["Counters/time"]);
 
  int specID = 0;
  // Store monitor counts in the beggining
  storeValue(specID++, monitorCounts, monitorCounts > 0 ? sqrt(monitorCounts) : 0.0, m_wavelength, m_dwavelength);
 
  storeValue(specID++, countingTime, 0.0, m_wavelength, m_dwavelength);
 
  // Store detector pixels
  for (auto count : data) {
    // Data uncertainties, computed according to the HFIR/IGOR reduction code
    // The following is what I would suggest instead...
    // error = count > 0 ? sqrt((double)count) : 0.0;
    double error = sqrt(0.5 + fabs(static_cast<double>(count) - 0.5));
    storeValue(specID++, count, error, m_wavelength, m_dwavelength);
  }
}
 
template <class T>
void LoadHFIRSANS::addRunProperty(const std::string &name, const T &value, const std::string &units) {
  g_log.debug() << "Adding Property to the Run: " << name << " -> " << value << "\n";
  m_workspace->mutableRun().addProperty(name, value, units, true);
}
 
template <class T> void LoadHFIRSANS::addRunTimeSeriesProperty(const std::string &name, const T &value) {
  g_log.debug() << "Adding Time Series Property to the Run: " << name << " -> " << value << "\n";
  API::Run &runDetails = m_workspace->mutableRun();
  auto *p = new Mantid::Kernel::TimeSeriesProperty<T>(name);
  p->addValue(DateAndTime::getCurrentTime(), value);
  runDetails.addLogData(p);
}
 
void LoadHFIRSANS::setBeamTrapRunProperty() {
 
  std::vector<double> trapDiameters = {76.2, 50.8, 76.2, 101.6};
  // default use the shortest trap
  double trapDiameterInUse = trapDiameters[1];
 
  std::vector<double> trapMotorPositions;
  trapMotorPositions.emplace_back(boost::lexical_cast<double>(m_metadata["Motor_Positions/trap_y_25mm"]));
  trapMotorPositions.emplace_back(boost::lexical_cast<double>(m_metadata["Motor_Positions/trap_y_50mm"]));
  trapMotorPositions.emplace_back(boost::lexical_cast<double>(m_metadata["Motor_Positions/trap_y_76mm"]));
  trapMotorPositions.emplace_back(boost::lexical_cast<double>(m_metadata["Motor_Positions/trap_y_101mm"]));
 
  // Check how many traps are in use (store indexes):
  std::vector<size_t> trapIndexInUse;
  for (size_t i = 0; i < trapMotorPositions.size(); i++) {
    if (trapMotorPositions[i] > 26.0) {
      // Resting positions are below 25. Make sure we have one trap in use!
      trapIndexInUse.emplace_back(i);
    }
  }
 
  g_log.debug() << "trapIndexInUse length:" << trapIndexInUse.size() << "\n";
 
  // store trap diameters in use
  std::vector<double> trapDiametersInUse;
  trapDiametersInUse.reserve(trapIndexInUse.size());
  std::transform(trapIndexInUse.cbegin(), trapIndexInUse.cend(), std::back_inserter(trapDiametersInUse),
                 [&trapDiameters](auto index) { return trapDiameters[index]; });
 
  g_log.debug() << "trapDiametersInUse length:" << trapDiametersInUse.size() << "\n";
 
  // The maximum value for the trapDiametersInUse is the trap in use
  auto trapDiameterInUseIt = std::max_element(trapDiametersInUse.begin(), trapDiametersInUse.end());
  if (trapDiameterInUseIt != trapDiametersInUse.end())
    trapDiameterInUse = *trapDiameterInUseIt;
 
  g_log.debug() << "trapDiameterInUse:" << trapDiameterInUse << "\n";
 
  addRunProperty<double>("beam-trap-diameter", trapDiameterInUse, "mm");
}
 
void LoadHFIRSANS::storeMetaDataIntoWS() {
 
  for (const auto &keyValuePair : m_metadata) {
    std::string key = keyValuePair.first;
    std::replace(key.begin(), key.end(), '/', '_');
    m_workspace->mutableRun().addProperty(key, keyValuePair.second, true);
  }
 
  addRunProperty<std::string>("start_time", m_startTime.toISO8601String(), "");
  addRunProperty<std::string>("run_start", m_startTime.toISO8601String(), "");
  m_workspace->mutableRun().setStartAndEndTime(m_startTime, m_endTime);
 
  setBeamTrapRunProperty();
 
  addRunProperty<double>("wavelength", m_wavelength, "Angstrom");
  addRunProperty<double>("wavelength-spread", m_dwavelength, "Angstrom");
  addRunProperty<double>("wavelength-spread-ratio", m_dwavelength / m_wavelength);
 
  addRunProperty<double>("monitor", boost::lexical_cast<double>(m_metadata["Counters/monitor"]));
  addRunProperty<double>("timer", boost::lexical_cast<double>(m_metadata["Counters/time"]), "sec");
 
  // XML 1.03: sample thickness is now in meters
  auto sample_thickness = boost::lexical_cast<double>(m_metadata["Header/Sample_Thickness"]);
  if (m_sansSpiceXmlFormatVersion >= 1.03) {
    g_log.debug() << "sans_spice_xml_format_version >= 1.03 :: "
                     "sample_thickness in mm. Converting to cm...";
    sample_thickness *= 0.1;
  }
  addRunProperty<double>("sample-thickness", sample_thickness, "cm");
 
  addRunProperty<double>("source-aperture-diameter",
                         boost::lexical_cast<double>(m_metadata["Header/source_aperture_size"]), "mm");
  addRunProperty<double>("source_aperture_diameter",
                         boost::lexical_cast<double>(m_metadata["Header/source_aperture_size"]), "mm");
 
  addRunProperty<double>("sample-aperture-diameter",
                         boost::lexical_cast<double>(m_metadata["Header/sample_aperture_size"]), "mm");
  addRunProperty<double>("sample_aperture_diameter",
                         boost::lexical_cast<double>(m_metadata["Header/sample_aperture_size"]), "mm");
 
  addRunProperty<double>("number-of-guides", boost::lexical_cast<double>(m_metadata["Motor_Positions/nguides"]));
}
 
void LoadHFIRSANS::runLoadInstrument() {
 
  const std::string &instrumentName = m_metadata["Header/Instrument"];
 
  auto loadInstrumentAlgorithm = createChildAlgorithm("LoadInstrument");
 
  // Now execute the Child Algorithm. Catch and log any error, but don't stop.
  try {
    loadInstrumentAlgorithm->setPropertyValue("InstrumentName", instrumentName);
    loadInstrumentAlgorithm->setProperty<API::MatrixWorkspace_sptr>("Workspace", m_workspace);
    loadInstrumentAlgorithm->setProperty("RewriteSpectraMap", Mantid::Kernel::OptionalBool(true));
    loadInstrumentAlgorithm->execute();
  } catch (std::invalid_argument &) {
    g_log.information("Invalid argument to LoadInstrument Child Algorithm");
  } catch (std::runtime_error &) {
    g_log.information("Unable to successfully run LoadInstrument Child Algorithm");
  }
}
 
void LoadHFIRSANS::rotateDetector() {
 
  // The angle is negative!
  double angle = -boost::lexical_cast<double>(m_metadata["Motor_Positions/det_west_wing_rot"]);
  g_log.notice() << "Rotating Wing Detector " << angle << " degrees." << '\n';
  addRunTimeSeriesProperty<double>("rotangle", angle);
}
 
void LoadHFIRSANS::setDetectorDistance() {
 
  m_sampleDetectorDistance = getProperty("SampleDetectorDistance");
 
  if (!isEmpty(m_sampleDetectorDistance)) {
    // SDD is as input
    g_log.debug() << "Getting the SampleDetectorDistance = " << m_sampleDetectorDistance
                  << " from the Algorithm input property.\n";
  } else if (m_metadata.find("Motor_Positions/sdd") != m_metadata.end()) {
    // Newest version: SDD as a specific tag
    m_sampleDetectorDistance = boost::lexical_cast<double>(m_metadata["Motor_Positions/sdd"]);
    m_sampleDetectorDistance *= 1000.0;
  } else if (m_metadata.find("Motor_Positions/sample_det_dist") != m_metadata.end()) {
    // Old Format
    auto sampleDetectorDistancePartial = boost::lexical_cast<double>(m_metadata["Motor_Positions/sample_det_dist"]);
    sampleDetectorDistancePartial *= 1000.0;
 
    auto sampleDetectorDistanceOffset = boost::lexical_cast<double>(m_metadata["Header/tank_internal_offset"]);
 
    auto sampleDetectorDistanceWindow = boost::lexical_cast<double>(m_metadata["Header/sample_to_flange"]);
 
    m_sampleDetectorDistance =
        sampleDetectorDistancePartial + sampleDetectorDistanceOffset + sampleDetectorDistanceWindow;
  } else {
    // New format:
    m_sampleDetectorDistance = boost::lexical_cast<double>(m_metadata["Motor_Positions/sample_det_dist"]);
    m_sampleDetectorDistance *= 1000.0;
  }
  g_log.debug() << "Sample Detector Distance = " << m_sampleDetectorDistance << " mm." << '\n';
  addRunProperty<double>("sample-detector-distance", m_sampleDetectorDistance, "mm");
  addRunProperty<double>("sample_detector_distance", m_sampleDetectorDistance, "mm");
 
  addRunTimeSeriesProperty<double>("sdd", m_sampleDetectorDistance);
}
 
void LoadHFIRSANS::moveDetector() {
 
  setDetectorDistance();
  auto translationDistance = boost::lexical_cast<double>(m_metadata["Motor_Positions/detector_trans"]);
  g_log.debug() << "Detector Translation = " << translationDistance << " mm." << '\n';
  addRunTimeSeriesProperty<double>("detector-translation", translationDistance);
}
 
std::string LoadHFIRSANS::getInstrumentStringParameter(const std::string &parameter) {
  std::vector<std::string> pars = m_workspace->getInstrument()->getStringParameter(parameter);
  if (pars.empty()) {
    g_log.warning() << "Parameter not found: " << parameter << " in the instrument parameter file.\n";
    return std::string();
  } else {
    g_log.debug() << "Found the parameter: " << parameter << " = " << pars[0] << " in the instrument parameter file.\n";
    return pars[0];
  }
}
 
double LoadHFIRSANS::getInstrumentDoubleParameter(const std::string &parameter) {
  std::vector<double> pars = m_workspace->getInstrument()->getNumberParameter(parameter);
  if (pars.empty()) {
    g_log.warning() << "Parameter not found in the instrument parameter file: " << parameter << "\n";
    return std::numeric_limits<double>::quiet_NaN();
  } else {
    g_log.debug() << "Found the parameter in the instrument parameter file: " << parameter << " = " << pars[0] << "\n";
    return pars[0];
  }
}
double LoadHFIRSANS::getSourceToSampleDistance() {
  // First let's try to get source_distance first:
  auto sourceToSampleDistance = boost::lexical_cast<double>(m_metadata["Header/source_distance"]);
  // XML 1.03: source distance is now in meters
  if (m_sansSpiceXmlFormatVersion >= 1.03) {
    sourceToSampleDistance *= 1000; // convert to mm
  }
  if (sourceToSampleDistance <= 0) {
    g_log.warning() << "Source To Sample Distance: Header/source_distance = " << sourceToSampleDistance
                    << ". Trying to calculate it from the number of guides used and offset." << '\n';
    const int nGuides = static_cast<int>(boost::lexical_cast<double>(m_metadata["Motor_Positions/nguides"]));
    // aperture-distances: array from the instrument parameters
    std::string guidesDistances = getInstrumentStringParameter("aperture-distances");
    std::vector<std::string> guidesDistancesSplit;
    boost::split(guidesDistancesSplit, guidesDistances, boost::is_any_of("\t ,"), boost::token_compress_on);
    sourceToSampleDistance = boost::lexical_cast<double>(guidesDistancesSplit[nGuides]);
    g_log.debug() << "Number of guides used = " << nGuides << " --> Raw SSD = " << sourceToSampleDistance << "mm.\n";
    auto sourceToSampleDistanceOffset = boost::lexical_cast<double>(m_metadata["Header/sample_aperture_to_flange"]);
    g_log.debug() << "SSD offset  = " << sourceToSampleDistanceOffset << "mm.\n";
    sourceToSampleDistance -= sourceToSampleDistanceOffset;
  }
  g_log.information() << "Source To Sample Distance = " << sourceToSampleDistance << "mm.\n";
  return sourceToSampleDistance;
}
 
void LoadHFIRSANS::setBeamDiameter() {
 
  double sourceToSampleDistance = getSourceToSampleDistance();
  addRunProperty<double>("source-sample-distance", sourceToSampleDistance, "mm");
  addRunProperty<double>("source_sample_distance", sourceToSampleDistance, "mm");
 
  const auto sampleAperture = boost::lexical_cast<double>(m_metadata["Header/sample_aperture_size"]);
  const auto sourceAperture = boost::lexical_cast<double>(m_metadata["Header/source_aperture_size"]);
  g_log.debug() << "Computing beam diameter. m_sampleDetectorDistance=" << m_sampleDetectorDistance
                << " SourceToSampleDistance=" << sourceToSampleDistance << " sourceAperture= " << sourceAperture
                << " sampleAperture=" << sampleAperture << "\n";
 
  const double beamDiameter =
      m_sampleDetectorDistance / sourceToSampleDistance * (sourceAperture + sampleAperture) + sampleAperture;
  addRunProperty<double>("beam-diameter", beamDiameter, "mm");
}
 
} // namespace Mantid::DataHandling