CreateSampleWorkspace.cpp

// 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 "MantidAlgorithms/CreateSampleWorkspace.h"
#include "MantidAPI/Axis.h"
#include "MantidAPI/FunctionDomain1D.h"
#include "MantidAPI/FunctionFactory.h"
#include "MantidAPI/FunctionProperty.h"
#include "MantidAPI/Run.h"
#include "MantidAPI/Sample.h"
#include "MantidDataObjects/EventWorkspace.h"
#include "MantidDataObjects/ScanningWorkspaceBuilder.h"
#include "MantidDataObjects/Workspace2D.h"
#include "MantidDataObjects/WorkspaceCreation.h"
#include "MantidGeometry/Instrument/RectangularDetector.h"
#include "MantidGeometry/Instrument/ReferenceFrame.h"
#include "MantidGeometry/Objects/ShapeFactory.h"
#include "MantidHistogramData/LinearGenerator.h"
#include "MantidIndexing/IndexInfo.h"
#include "MantidKernel/BoundedValidator.h"
#include "MantidKernel/ListValidator.h"
#include "MantidKernel/MersenneTwister.h"
#include "MantidKernel/UnitFactory.h"
#include "MantidTypes/SpectrumDefinition.h"

#include <algorithm>
#include <cmath>
#include <ctime>
#include <iterator>
#include <numeric>
#include <stdexcept>

namespace Mantid::Algorithms {
using namespace Kernel;
using namespace API;
using namespace Geometry;
using namespace DataObjects;
using namespace HistogramData;
using namespace Indexing;
using Mantid::MantidVec;
using Mantid::MantidVecPtr;
using Types::Core::DateAndTime;
using Types::Event::TofEvent;

// Register the algorithm into the AlgorithmFactory
DECLARE_ALGORITHM(CreateSampleWorkspace)

/** Constructor
 */
CreateSampleWorkspace::CreateSampleWorkspace() : m_randGen(nullptr) {}

/// Algorithm's name for identification. @see Algorithm::name
const std::string CreateSampleWorkspace::name() const { return "CreateSampleWorkspace"; }

/// Algorithm's version for identification. @see Algorithm::version
int CreateSampleWorkspace::version() const { return 1; }

/// Algorithm's category for identification. @see Algorithm::category
const std::string CreateSampleWorkspace::category() const { return "Utility\\Workspaces"; }

/** Initialize the algorithm's properties.
 */
void CreateSampleWorkspace::init() {
  declareProperty(std::make_unique<WorkspaceProperty<>>("OutputWorkspace", "", Direction::Output),
                  "An output workspace.");
  std::vector<std::string> typeOptions{"Histogram", "Event"};
  declareProperty("WorkspaceType", "Histogram", std::make_shared<StringListValidator>(typeOptions),
                  "The type of workspace to create (default: Histogram)");

  // pre-defined function strings these use $PCx$ to define peak centres values
  // that will be replaced before use
  //$PC0$ is the far left of the data, and $PC10$ is the far right, and
  // therefore will often not be used
  //$PC5$ is the centre of the data
  m_preDefinedFunctionmap.emplace("One Peak", "name=LinearBackground, A0=0.3; name=Gaussian, "
                                              "PeakCentre=$PC5$, Height=10, Sigma=0.7;");
  m_preDefinedFunctionmap.emplace("Multiple Peaks", "name=LinearBackground, A0=0.3;name=Gaussian, "
                                                    "PeakCentre=$PC3$, Height=10, Sigma=0.7;name=Gaussian, "
                                                    "PeakCentre=$PC6$, Height=8, Sigma=0.5");
  m_preDefinedFunctionmap.emplace("Flat background", "name=LinearBackground, A0=1;");
  m_preDefinedFunctionmap.emplace("Exp Decay", "name=ExpDecay, Height=100, Lifetime=1000;");
  m_preDefinedFunctionmap.emplace("Powder Diffraction", "name= LinearBackground,A0=0.0850208,A1=-4.89583e-06;"
                                                        "name=Gaussian,Height=0.584528,PeakCentre=$PC1$,Sigma=14.3772;"
                                                        "name=Gaussian,Height=1.33361,PeakCentre=$PC2$,Sigma=15.2516;"
                                                        "name=Gaussian,Height=1.74691,PeakCentre=$PC3$,Sigma=15.8395;"
                                                        "name=Gaussian,Height=0.950388,PeakCentre=$PC4$,Sigma=19.8408;"
                                                        "name=Gaussian,Height=1.92185,PeakCentre=$PC5$,Sigma=18.0844;"
                                                        "name=Gaussian,Height=3.64069,PeakCentre=$PC6$,Sigma=19.2404;"
                                                        "name=Gaussian,Height=2.8998,PeakCentre=$PC7$,Sigma=21.1127;"
                                                        "name=Gaussian,Height=2.05237,PeakCentre=$PC8$,Sigma=21.9932;"
                                                        "name=Gaussian,Height=8.40976,PeakCentre=$PC9$,Sigma=25.2751;");
  m_preDefinedFunctionmap.emplace("Quasielastic", "name=Lorentzian,FWHM=0.3,PeakCentre=$PC5$,Amplitude=0.8;"
                                                  "name=Lorentzian,FWHM=0.1,PeakCentre=$PC5$,Amplitude=1;"
                                                  "name=LinearBackground,A0=0.1");
  m_preDefinedFunctionmap.emplace("Quasielastic Tunnelling",
                                  "name=LinearBackground,A0=0.1;"
                                  "name=Lorentzian,FWHM=0.1,PeakCentre=$PC5$,Amplitude=1;"
                                  "name=Lorentzian,FWHM=0.05,PeakCentre=$PC7$,Amplitude=0.04;"
                                  "name=Lorentzian,FWHM=0.05,PeakCentre=$PC3$,Amplitude=0.04;"
                                  "name=Lorentzian,FWHM=0.05,PeakCentre=$PC8$,Amplitude=0.02;"
                                  "name=Lorentzian,FWHM=0.05,PeakCentre=$PC2$,Amplitude=0.02");
  m_preDefinedFunctionmap.emplace("User Defined", "");
  std::vector<std::string> functionOptions;
  functionOptions.reserve(m_preDefinedFunctionmap.size());
  std::transform(m_preDefinedFunctionmap.cbegin(), m_preDefinedFunctionmap.cend(), std::back_inserter(functionOptions),
                 [](const auto &preDefinedFunction) { return preDefinedFunction.first; });
  declareProperty("Function", "One Peak", std::make_shared<StringListValidator>(functionOptions),
                  "Preset options of the data to fill the workspace with");
  declareProperty("UserDefinedFunction", "", "Parameters defining the fitting function and its initial values");

  declareProperty("XUnit", "TOF", "The unit to assign to the XAxis (default:\"TOF\")");
  declareProperty("XMin", 0.0, "The minimum X axis value (default:0)");
  declareProperty("XMax", 20000.0, "The maximum X axis value (default:20000)");
  declareProperty("BinWidth", 200.0, std::make_shared<BoundedValidator<double>>(0, 100000, true),
                  "The bin width of the X axis (default:200)");
  declareProperty("NumEvents", 1000, std::make_shared<BoundedValidator<int>>(0, 100000),
                  "The number of events per detector, this is only used for "
                  "EventWorkspaces (default:1000)");
  declareProperty("Random", false, "Whether to randomise the placement of events and data (default:false)");

  declareProperty("NumScanPoints", 1, std::make_shared<BoundedValidator<int>>(0, 360, true),
                  "Add a number of time indexed detector scan points to the "
                  "instrument. The detectors are rotated in 1 degree "
                  "increments around the the sample position in the x-z plane. "
                  "Minimum (default) is 1 scan point, which gives a "
                  "non-scanning workspace.");

  declareProperty("InstrumentName", "basic_rect", Direction::Input);
  declareProperty("NumBanks", 2, std::make_shared<BoundedValidator<int>>(0, 100),
                  "The Number of banks in the instrument (default:2)");
  declareProperty("NumMonitors", 0, std::make_shared<BoundedValidator<int>>(0, 100),
                  "The number of monitors in the instrument (default:0)");
  declareProperty("BankPixelWidth", 10, std::make_shared<BoundedValidator<int>>(0, 10000),
                  "The number of pixels in horizontally and vertically in a "
                  "bank (default:10)");

  declareProperty("PixelDiameter", 0.008, std::make_shared<BoundedValidator<double>>(0, 0.1),
                  "Length in meters of one side of a pixel assumed to be square");

  declareProperty("PixelHeight", 0.0002, std::make_shared<BoundedValidator<double>>(0, 0.1),
                  "Height in meters of the pixel");

  declareProperty("PixelSpacing", 0.008, std::make_shared<BoundedValidator<double>>(0, 100000, true),
                  "Distance between the center of adjacent pixels in a uniform grid "
                  "(default: 0.008 meters)");

  declareProperty("BankDistanceFromSample", 5.0, std::make_shared<BoundedValidator<double>>(0, 1000, true),
                  "The distance along the beam direction from the sample to "
                  "bank in meters (default:5.0)");
  declareProperty("SourceDistanceFromSample", 10.0, std::make_shared<BoundedValidator<double>>(0, 1000, true),
                  "The distance along the beam direction from the source to "
                  "the sample in meters (default:10.0)");

  /* Aggregate properties in groups */
  std::string instrumentGroupName = "Instrument";
  setPropertyGroup("InstrumentName", instrumentGroupName);
  setPropertyGroup("NumMonitors", instrumentGroupName);
  setPropertyGroup("BankDistanceFromSample", instrumentGroupName);
  setPropertyGroup("SourceDistanceFromSample", instrumentGroupName);
  setPropertyGroup("NumBanks", instrumentGroupName);
  setPropertyGroup("BankPixelWidth", instrumentGroupName);
  setPropertyGroup("PixelDiameter", instrumentGroupName);
  setPropertyGroup("PixelHeight", instrumentGroupName);
  setPropertyGroup("PixelSpacing", instrumentGroupName);
}

//----------------------------------------------------------------------------------------------
/** Execute the algorithm.
 */
void CreateSampleWorkspace::exec() {
  const std::string wsType = getProperty("WorkspaceType");
  const std::string preDefinedFunction = getProperty("Function");
  const std::string userDefinedFunction = getProperty("UserDefinedFunction");
  const std::string instrName = getPropertyValue("InstrumentName");
  const int numBanks = getProperty("NumBanks");
  const int numMonitors = getProperty("NumMonitors");
  const int bankPixelWidth = getProperty("BankPixelWidth");
  const int numEvents = getProperty("NumEvents");
  const bool isRandom = getProperty("Random");
  const std::string xUnit = getProperty("XUnit");
  const double xMin = getProperty("XMin");
  const double xMax = getProperty("XMax");
  double binWidth = getProperty("BinWidth");
  const double pixelDiameter = getProperty("PixelDiameter");
  const double pixelHeight = getProperty("PixelHeight");
  const double pixelSpacing = getProperty("PixelSpacing");
  const double bankDistanceFromSample = getProperty("BankDistanceFromSample");
  const double sourceSampleDistance = getProperty("SourceDistanceFromSample");
  const int numScanPoints = getProperty("NumScanPoints");

  if (xMax <= xMin) {
    throw std::invalid_argument("XMax must be larger than XMin");
  }

  if (pixelSpacing < pixelDiameter) {
    g_log.error() << "PixelSpacing (the distance between pixel centers in the uniform grid)"
                     "is smaller than the PixelDiameter (square pixel dimension)"
                  << '\n';
    throw std::invalid_argument("PixelSpacing must be at least as large as pixelDiameter");
  }

  if (binWidth > (xMax - xMin)) {
    // the bin width is so large that there is less than one bin - so adjust it
    // down
    binWidth = xMax - xMin;
    g_log.warning() << "The bin width is so large that there is less than one "
                       "bin - it has been changed to "
                    << binWidth << '\n';
  }

  std::string functionString;
  if (m_preDefinedFunctionmap.find(preDefinedFunction) != m_preDefinedFunctionmap.end()) {
    // extract pre-defined string
    functionString = m_preDefinedFunctionmap[preDefinedFunction];
  }
  if (functionString.empty()) {
    functionString = userDefinedFunction;
  }

  if (!m_randGen) {
    int seedValue = 0;
    if (isRandom) {
      seedValue = static_cast<int>(std::time(nullptr));
    }
    m_randGen = std::make_unique<Kernel::MersenneTwister>(seedValue);
  }

  int numPixels = numBanks * bankPixelWidth * bankPixelWidth;

  Progress progress(this, 0.0, 1.0, numBanks);

  // Create an instrument with one or more rectangular banks.
  Instrument_sptr inst =
      createTestInstrumentRectangular(progress, numBanks, numMonitors, bankPixelWidth, pixelDiameter, pixelHeight,
                                      pixelSpacing, bankDistanceFromSample, sourceSampleDistance, instrName);

  auto numBins = static_cast<int>((xMax - xMin) / binWidth);

  MatrixWorkspace_sptr ws;
  if (wsType == "Event") {
    ws = createEventWorkspace(numPixels, numBins, numMonitors, numEvents, xMin, binWidth, inst, functionString,
                              isRandom);
  } else if (numScanPoints > 1) {
    ws = createScanningWorkspace(numBins, xMin, binWidth, inst, functionString, isRandom, numScanPoints);
  } else {
    ws = createHistogramWorkspace(numPixels, numBins, numMonitors, xMin, binWidth, inst, functionString, isRandom);
  }
  // add chopper
  this->addChopperParameters(ws);

  // Set the Unit of the X Axis
  try {
    ws->getAxis(0)->unit() = UnitFactory::Instance().create(xUnit);
  } catch (Exception::NotFoundError &) {
    ws->getAxis(0)->unit() = UnitFactory::Instance().create("Label");
    Unit_sptr unit = ws->getAxis(0)->unit();
    std::shared_ptr<Units::Label> label = std::dynamic_pointer_cast<Units::Label>(unit);
    label->setLabel(xUnit, xUnit);
  }

  auto sampleSphere = createSphere(0.001, V3D(0.0, 0.0, 0.0), "sample-shape");
  ws->mutableSample().setShape(sampleSphere);

  ws->setYUnit("Counts");
  ws->setTitle("Test Workspace");
  DateAndTime run_start("2010-01-01T00:00:00");
  DateAndTime run_end("2010-01-01T01:00:00");
  Run &theRun = ws->mutableRun();
  // belt and braces use both approaches for setting start and end times
  theRun.setStartAndEndTime(run_start, run_end);
  theRun.addLogData(new PropertyWithValue<std::string>("run_start", run_start.toISO8601String()));
  theRun.addLogData(new PropertyWithValue<std::string>("run_end", run_end.toISO8601String()));

  // Assign it to the output workspace property
  setProperty("OutputWorkspace", ws);
  ;
}
/** Add chopper to the existing matrix workspace
@param ws  -- shared pointer to existing matrix workspace which has instrument
and chopper

@returns workspace modified to have Fermi chopper added to it.
*/
void CreateSampleWorkspace::addChopperParameters(API::MatrixWorkspace_sptr &ws) {

  auto testInst = ws->getInstrument();
  auto chopper = testInst->getComponentByName("chopper-position");

  // add chopper parameters
  auto &paramMap = ws->instrumentParameters();
  const std::string description("The initial rotation phase of the disk used to calculate the time"
                                " for neutrons arriving at the chopper according to the formula time = "
                                "delay + initial_phase/Speed");
  paramMap.add<double>("double", chopper.get(), "initial_phase", -3000., &description);
  paramMap.add<std::string>("string", chopper.get(), "ChopperDelayLog", "fermi_delay");
  paramMap.add<std::string>("string", chopper.get(), "ChopperSpeedLog", "fermi_speed");
  paramMap.add<std::string>("string", chopper.get(), "FilterBaseLog", "is_running");
  paramMap.add<bool>("bool", chopper.get(), "filter_with_derivative", false);
}

/** Create histogram workspace
 */
MatrixWorkspace_sptr CreateSampleWorkspace::createHistogramWorkspace(int numPixels, int numBins, int numMonitors,
                                                                     double x0, double binDelta,
                                                                     const Geometry::Instrument_sptr &inst,
                                                                     const std::string &functionString, bool isRandom) {
  BinEdges x(numBins + 1, LinearGenerator(x0, binDelta));

  // there is a oddity here that y is evaluated from x=0, and x is from XMin
  // changing it requires changing unit tests that use this algorithm
  std::vector<double> xValues(cbegin(x), cend(x) - 1);
  Counts y(evalFunction(functionString, xValues, isRandom ? 1 : 0));

  std::vector<SpectrumDefinition> specDefs(numPixels + numMonitors);
  for (int wi = 0; wi < numMonitors + numPixels; wi++)
    specDefs[wi].add(wi < numMonitors ? numPixels + wi : wi - numMonitors);
  Indexing::IndexInfo indexInfo(numPixels + numMonitors);
  indexInfo.setSpectrumDefinitions(std::move(specDefs));

  return create<Workspace2D>(inst, indexInfo, Histogram(x, y));
}

/** Create scanning histogram workspace
 */
MatrixWorkspace_sptr CreateSampleWorkspace::createScanningWorkspace(int numBins, double x0, double binDelta,
                                                                    const Geometry::Instrument_sptr &inst,
                                                                    const std::string &functionString, bool isRandom,
                                                                    int numScanPoints) {
  auto builder = ScanningWorkspaceBuilder(inst, numScanPoints, numBins);

  auto angles = std::vector<double>();
  auto timeRanges = std::vector<double>();
  for (int i = 0; i < numScanPoints; ++i) {
    angles.emplace_back(double(i));
    timeRanges.emplace_back(double(i + 1));
  }

  builder.setTimeRanges(Types::Core::DateAndTime(0), timeRanges);
  builder.setRelativeRotationsForScans(angles, inst->getSample()->getPos(), V3D(0, 1, 0));

  BinEdges x(numBins + 1, LinearGenerator(x0, binDelta));

  std::vector<double> xValues(cbegin(x), cend(x) - 1);
  Counts y(evalFunction(functionString, xValues, isRandom ? 1 : 0));

  builder.setHistogram(Histogram(x, y));

  return builder.buildWorkspace();
}

/** Create event workspace
 */
EventWorkspace_sptr CreateSampleWorkspace::createEventWorkspace(int numPixels, int numBins, int numMonitors,
                                                                int numEvents, double x0, double binDelta,
                                                                const Geometry::Instrument_sptr &inst,
                                                                const std::string &functionString, bool isRandom) {
  DateAndTime run_start("2010-01-01T00:00:00");

  std::vector<SpectrumDefinition> specDefs(numPixels + numMonitors);
  for (int wi = 0; wi < numMonitors + numPixels; wi++)
    specDefs[wi].add(wi < numMonitors ? numPixels + wi : wi - numMonitors);
  Indexing::IndexInfo indexInfo(numPixels + numMonitors);
  indexInfo.setSpectrumDefinitions(std::move(specDefs));

  // add one to the number of bins as this is histogram
  int numXBins = numBins + 1;
  BinEdges x(numXBins, LinearGenerator(x0, binDelta));

  auto retVal = create<EventWorkspace>(inst, indexInfo, x);

  std::vector<double> xValues(x.cbegin(), x.cend() - 1);
  std::vector<double> yValues = evalFunction(functionString, xValues, isRandom ? 1 : 0);

  // we need to normalise the results and then multiply by the number of events
  // to find the events per bin
  double sum_of_elems = std::accumulate(yValues.begin(), yValues.end(), 0.0);
  double event_distrib_factor = numEvents / sum_of_elems;
  using std::placeholders::_1;
  std::transform(yValues.begin(), yValues.end(), yValues.begin(),
                 std::bind(std::multiplies<double>(), event_distrib_factor, _1));
  // the array should now contain the number of events required per bin

  // Make fake events
  size_t workspaceIndex = 0;

  const double hourInSeconds = 60 * 60;
  for (int wi = 0; wi < numPixels + numMonitors; wi++) {
    EventList &el = retVal->getSpectrum(workspaceIndex);
    for (int i = 0; i < numBins; ++i) {
      // create randomised events within the bin to match the number required -
      // calculated in yValues earlier
      auto eventsInBin = static_cast<int>(yValues[i]);
      for (int q = 0; q < eventsInBin; q++) {
        DateAndTime pulseTime = run_start + (m_randGen->nextValue() * hourInSeconds);
        el += TofEvent((i + m_randGen->nextValue()) * binDelta + x0, pulseTime);
      }
    }
    workspaceIndex++;
  }

  return retVal;
}
//----------------------------------------------------------------------------------------------
/**
 * Evaluates a function and returns the values as a vector
 *
 *
 * @param functionString :: the function string
 * @param xVal :: A vector of the x values
 * @param noiseScale :: A scaling factor for niose to be added to the data, 0=
 *no noise
 * @returns the calculated values
 */
std::vector<double> CreateSampleWorkspace::evalFunction(const std::string &functionString,
                                                        const std::vector<double> &xVal, double noiseScale = 0) {
  size_t xSize = xVal.size();
  // replace $PCx$ values
  std::string parsedFuncString = functionString;
  for (int x = 0; x <= 10; ++x) {
    // get the rough peak centre value
    auto index = static_cast<int>((xSize / 10) * x);
    if ((x == 10) && (index > 0))
      --index;
    double replace_val = xVal[index];
    std::ostringstream tokenStream;
    tokenStream << "$PC" << x << "$";
    std::string token = tokenStream.str();
    std::string replaceStr = boost::lexical_cast<std::string>(replace_val);
    replaceAll(parsedFuncString, token, replaceStr);
  }
  g_log.information(parsedFuncString);

  IFunction_sptr func_sptr = FunctionFactory::Instance().createInitialized(parsedFuncString);
  FunctionDomain1DVector fd(xVal);
  FunctionValues fv(fd);
  func_sptr->function(fd, fv);

  auto results = fv.toVector();
  for (size_t x = 0; x < xSize; ++x) {
    if (noiseScale != 0) {
      results[x] += ((m_randGen->nextValue() - 0.5) * noiseScale);
    }
    // no negative values please  - it messes up the error calculation
    results[x] = fabs(results[x]);
  }
  return results;
}

void CreateSampleWorkspace::replaceAll(std::string &str, const std::string &from, const std::string &to) {
  if (from.empty())
    return;
  size_t start_pos = 0;
  while ((start_pos = str.find(from, start_pos)) != std::string::npos) {
    str.replace(start_pos, from.length(), to);
    start_pos += to.length(); // In case 'to' contains 'from', like replacing
                              // 'x' with 'yx'
  }
}

//----------------------------------------------------------------------------------------------
/**
 * Create an test instrument with n panels of rectangular detectors,
 * pixels*pixels in size, a source and spherical sample shape.
 *
 * Banks' lower-left corner is at position (0,0,5*banknum) and they go up to
 * (pixels*0.008, pixels*0.008, Z). Pixels are 4 mm wide.
 *
 * Optionally include monitors 10 cm x 10 cm, with the first positioned between
 * the sample and the first bank, and the rest between the banks.
 *
 * @param progress :: progress indicator
 * @param numBanks :: number of rectangular banks to create
 * @param numMonitors :: number of monitors to create
 * @param pixels :: number of pixels in each direction.
 * @param pixelDiameter:: width of pixel in relevant dimension
 * @param pixelHeight :: z-extent of pixel
 * @param pixelSpacing :: distance between pixel centers
 * @param bankDistanceFromSample :: Distance of first bank from sample (defaults
 *to 5.0m)
 * @param sourceSampleDistance :: The distance from the source to the sample
 * @param instrName :: Name of the underlying instrument, can be used to mock existing beamlines
 * @returns A shared pointer to the generated instrument
 */
Instrument_sptr CreateSampleWorkspace::createTestInstrumentRectangular(
    API::Progress &progress, int numBanks, int numMonitors, int pixels, double pixelDiameter, double pixelHeight,
    double pixelSpacing, const double bankDistanceFromSample, const double sourceSampleDistance,
    const std::string &instrName) {
  auto testInst = std::make_shared<Instrument>(instrName);
  // The instrument is going to be set up with z as the beam axis and y as the
  // vertical axis.
  testInst->setReferenceFrame(std::make_shared<ReferenceFrame>(Y, Z, Left, ""));

  /* Captain! This is wrong */
  const double cylRadius(pixelDiameter / 2);
  const double cylHeight(pixelHeight);
  // One object
  auto pixelShape =
      createCappedCylinder(cylRadius, cylHeight, V3D(0.0, -cylHeight / 2.0, 0.0), V3D(0., 1.0, 0.), "pixel-shape");

  for (int banknum = 1; banknum <= numBanks; banknum++) {
    // Make a new bank
    std::ostringstream bankname;
    bankname << "bank" << banknum;

    RectangularDetector *bank = new RectangularDetector(bankname.str());
    bank->initialize(pixelShape, pixels, 0.0, pixelSpacing, pixels, 0.0, pixelSpacing, banknum * pixels * pixels, true,
                     pixels);

    // Mark them all as detectors
    for (int x = 0; x < pixels; x++) {
      for (int y = 0; y < pixels; y++) {
        std::shared_ptr<Detector> detector = bank->getAtXY(x, y);
        if (detector) {
          // Mark it as a detector (add to the instrument cache)
          testInst->markAsDetector(detector.get());
        }
      }
    }

    testInst->add(bank);
    // Set the bank along the z-axis of the instrument. (beam direction).
    bank->setPos(V3D(0.0, 0.0, bankDistanceFromSample * banknum));

    progress.report();
  }

  int monitorsStart = (numBanks + 1) * pixels * pixels;

  auto monitorShape =
      createCappedCylinder(0.1, 0.1, V3D(0.0, -cylHeight / 2.0, 0.0), V3D(0., 1.0, 0.), "monitor-shape");

  for (int monitorNumber = monitorsStart; monitorNumber < monitorsStart + numMonitors; monitorNumber++) {
    std::string monitorName = "monitor" + std::to_string(monitorNumber - monitorsStart + 1);

    Detector *detector = new Detector(monitorName, monitorNumber, monitorShape, testInst.get());
    // Mark it as a monitor (add to the instrument cache)
    testInst->markAsMonitor(detector);

    testInst->add(detector);
    // Set the bank along the z-axis of the instrument, between the detectors.
    detector->setPos(V3D(0.0, 0.0, bankDistanceFromSample * (monitorNumber - monitorsStart + 0.5)));
  }

  // Define a source component
  ObjComponent *source = new ObjComponent("moderator", IObject_sptr(new CSGObject), testInst.get());
  source->setPos(V3D(0.0, 0.0, -sourceSampleDistance));
  testInst->add(source);
  testInst->markAsSource(source);

  // Add chopper
  ObjComponent *chopper = new ObjComponent("chopper-position", IObject_sptr(new CSGObject), testInst.get());
  chopper->setPos(V3D(0.0, 0.0, -0.25 * sourceSampleDistance));
  testInst->add(chopper);

  // Define a sample position
  Component *sample = new Component("sample", testInst.get());
  testInst->setPos(0.0, 0.0, 0.0);
  testInst->add(sample);
  testInst->markAsSamplePos(sample);

  return testInst;
}

//----------------------------------------------------------------------------------------------
/**
 * Create a capped cylinder object
 */
IObject_sptr CreateSampleWorkspace::createCappedCylinder(double radius, double height, const V3D &baseCentre,
                                                         const V3D &axis, const std::string &id) {
  std::ostringstream xml;
  xml << "<cylinder id=\"" << id << "\">"
      << "<centre-of-bottom-base x=\"" << baseCentre.X() << "\" y=\"" << baseCentre.Y() << "\" z=\"" << baseCentre.Z()
      << "\"/>"
      << "<axis x=\"" << axis.X() << "\" y=\"" << axis.Y() << "\" z=\"" << axis.Z() << "\"/>"
      << "<radius val=\"" << radius << "\" />"
      << "<height val=\"" << height << "\" />"
      << "</cylinder>";

  ShapeFactory shapeMaker;
  return shapeMaker.createShape(xml.str());
}

//----------------------------------------------------------------------------------------------

/**
 * Create a sphere object
 */
IObject_sptr CreateSampleWorkspace::createSphere(double radius, const V3D &centre, const std::string &id) {
  ShapeFactory shapeMaker;
  std::ostringstream xml;
  xml << "<sphere id=\"" << id << "\">"
      << "<centre x=\"" << centre.X() << "\"  y=\"" << centre.Y() << "\" z=\"" << centre.Z() << "\" />"
      << "<radius val=\"" << radius << "\" />"
      << "</sphere>";
  return shapeMaker.createShape(xml.str());
}

} // namespace Mantid::Algorithms