LoadQKK.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/LoadQKK.h"
 
#include "MantidAPI/Axis.h"
#include "MantidAPI/FileProperty.h"
#include "MantidAPI/RegisterFileLoader.h"
#include "MantidDataObjects/Workspace2D.h"
#include "MantidDataObjects/WorkspaceCreation.h"
#include "MantidGeometry/Instrument.h"
#include "MantidGeometry/Instrument/RectangularDetector.h"
#include "MantidGeometry/Objects/ShapeFactory.h"
#include "MantidIndexing/IndexInfo.h"
#include "MantidKernel/UnitFactory.h"
#include "MantidNexus/NexusClasses.h"
 
#include <Poco/File.h>
 
#include <fstream>
 
using namespace Mantid::DataHandling;
using namespace Mantid::API;
using namespace Mantid::Kernel;
 
namespace Mantid::DataHandling {
 
// Register the algorithm into the AlgorithmFactory
DECLARE_NEXUS_FILELOADER_ALGORITHM(LoadQKK)
 
 
int LoadQKK::confidence(Kernel::NexusDescriptor &descriptor) const {
  const auto &firstEntryName = descriptor.firstEntryNameType().first;
  if (descriptor.pathExists("/" + firstEntryName + "/data/hmm_xy"))
    return 80;
  else
    return 0;
}
 
void LoadQKK::init() {
  // Declare the Filename algorithm property. Mandatory. Sets the path to the
  // file to load.
  declareProperty(std::make_unique<API::FileProperty>("Filename", "", API::FileProperty::Load, ".nx.hdf"),
                  "The input filename of the stored data");
  // Declare the OutputWorkspace property. This sets the name of the workspace
  // to be filled with the data
  // from the file.
  declareProperty(std::make_unique<API::WorkspaceProperty<>>("OutputWorkspace", "", Kernel::Direction::Output));
}
 
void LoadQKK::exec() {
  using namespace Mantid::API;
  // Get the name of the file.
  std::string filename = getPropertyValue("Filename");
 
  // Open the root.
  NeXus::NXRoot root(filename);
  // Open the first NXentry found in the file.
  NeXus::NXEntry entry = root.openFirstEntry();
  // Open NXdata group with name "data"
  NeXus::NXData data = entry.openNXData("data");
  // Read in wavelength value
  double wavelength = static_cast<double>(data.getFloat("wavelength"));
  // open the data set with the counts. It is identified by the signal=1
  // attribute
  NeXus::NXInt hmm = data.openIntData();
  // Read the data into memory
  hmm.load();
 
  // Get the wavelength spread
  double wavelength_spread = static_cast<double>(entry.getFloat("instrument/velocity_selector/wavelength_spread"));
  double wavelength0 = wavelength - wavelength_spread / 2;
  double wavelength1 = wavelength + wavelength_spread / 2;
 
  // hmm is a 3d array with axes: sample_x, y_pixel_offset, x_pixel_offset
  size_t ny = hmm.dim1(); // second dimension
  size_t nx = hmm.dim2(); // third dimension
  size_t nHist = ny * nx; // number of spectra in the dataset
  if (nHist == 0) {
    throw std::runtime_error("Error in data dimensions: " + std::to_string(ny) + " X " + std::to_string(nx));
  }
 
  // Build instrument geometry
 
  // Create a new instrument and set its name
  std::string instrumentname = "QUOKKA";
  Geometry::Instrument_sptr instrument(new Geometry::Instrument(instrumentname));
 
  // Add dummy source and samplepos to instrument
 
  // Create an instrument component wich will represent the sample position.
  Geometry::Component *samplepos = new Geometry::Component("Sample", instrument.get());
  instrument->add(samplepos);
  instrument->markAsSamplePos(samplepos);
  // Put the sample in the centre of the coordinate system
  samplepos->setPos(0.0, 0.0, 0.0);
 
  // Create a component to represent the source
  Geometry::ObjComponent *source = new Geometry::ObjComponent("Source", instrument.get());
  instrument->add(source);
  instrument->markAsSource(source);
 
  // Read in the L1 value and place the source at (0,0,-L1)
  double l1 = static_cast<double>(entry.getFloat("instrument/parameters/L1"));
  source->setPos(0.0, 0.0, -1.0 * l1);
 
  // Create a component for the detector.
 
  // We assumed that these are the dimensions of the detector, and height is in
  // y direction and width is in x direction
  double height = static_cast<double>(entry.getFloat("instrument/detector/active_height"));
  double width = static_cast<double>(entry.getFloat("instrument/detector/active_width"));
  // Convert them to metres
  height /= 1000;
  width /= 1000;
 
  // We assumed that individual pixels have the same size and shape of a cuboid
  // with dimensions:
  double pixel_height = height / static_cast<double>(ny);
  double pixel_width = width / static_cast<double>(nx);
  // Create size strings for shape creation
  std::string pixel_height_str = boost::lexical_cast<std::string>(pixel_height / 2);
  std::string pixel_width_str = boost::lexical_cast<std::string>(pixel_width / 2);
  // Set the depth of a pixel to a very small number
  std::string pixel_depth_str = "0.00001";
 
  // Create a RectangularDetector which represents a rectangular array of pixels
  Geometry::RectangularDetector *bank = new Geometry::RectangularDetector("bank", instrument.get());
  // Define shape of a pixel as an XML string. See
  // http://www.mantidproject.org/HowToDefineGeometricShape for details
  // on shapes in Mantid.
  std::string detXML = "<cuboid id=\"pixel\">"
                       "<left-front-bottom-point   x= \"" +
                       pixel_width_str + "\" y=\"-" + pixel_height_str +
                       "\" z=\"0\"  />"
                       "<left-front-top-point      x= \"" +
                       pixel_width_str + "\" y=\"-" + pixel_height_str + "\" z=\"" + pixel_depth_str +
                       "\"  />"
                       "<left-back-bottom-point    x=\"-" +
                       pixel_width_str + "\" y=\"-" + pixel_height_str +
                       "\" z=\"0\"  />"
                       "<right-front-bottom-point  x= \"" +
                       pixel_width_str + "\" y= \"" + pixel_height_str +
                       "\" z=\"0\"  />"
                       "</cuboid>";
  // Create a shape object which will be shared by all pixels.
  auto shape = Geometry::ShapeFactory().createShape(detXML);
  // Initialise the detector specifying the sizes.
  bank->initialize(shape, int(nx), 0, pixel_width, int(ny), 0, pixel_height, 1, true, int(nx));
  for (int i = 0; i < static_cast<int>(ny); ++i)
    for (int j = 0; j < static_cast<int>(nx); ++j) {
      instrument->markAsDetector(bank->getAtXY(j, i).get());
    }
  // Position the detector so the z axis goes through its centre
  bank->setPos(-width / 2, -height / 2, 0);
 
  // Create a workspace with nHist spectra and a single y bin.
  auto outputWorkspace =
      DataObjects::create<DataObjects::Workspace2D>(instrument, Indexing::IndexInfo(nHist), HistogramData::BinEdges(2));
  // Set the units of the x axis as Wavelength
  outputWorkspace->getAxis(0)->unit() = UnitFactory::Instance().create("Wavelength");
  // Set the units of the data as Counts
  outputWorkspace->setYUnitLabel("Counts");
 
  using namespace HistogramData;
  const BinEdges binEdges = {wavelength0, wavelength1};
  for (size_t index = 0; index < nHist; ++index) {
    auto x = static_cast<int>(index % nx);
    auto y = static_cast<int>(index / nx);
    auto c = hmm(0, x, y);
 
    Counts yValue = {static_cast<double>(c)};
    outputWorkspace->setHistogram(index, binEdges, yValue);
  }
 
  outputWorkspace->setTitle(entry.getString("experiment/title"));
  setProperty("OutputWorkspace", std::move(outputWorkspace));
}
 
} // namespace Mantid::DataHandling