/**
* Loads the mapping between index -> set of detector IDs
*
* If "detector_index", "detector_count" and "detector_list" are all present,
* use these to get the mapping, otherwise spectrum number = detector ID
* (one-to-one)
*
* The spectrum spectrum_index[i] maps to detector_count[i] detectors, whose
* detector IDs are in detector_list starting at the index detector_index[i]
*
* @returns :: map of index -> detector IDs
* @throws std::runtime_error if fails to read data from file
*/
std::map<int, std::set<int>>
LoadMuonNexus2::loadDetectorMapping(const Mantid::NeXus::NXInt &spectrumIndex) {
std::map<int, std::set<int>> mapping;
const int nSpectra = spectrumIndex.dim0();
// Find and open the data group
NXRoot root(getPropertyValue("Filename"));
NXEntry entry = root.openEntry(m_entry_name);
const std::string detectorName = [&entry]() {
// Only the first NXdata found
for (auto &group : entry.groups()) {
std::string className = group.nxclass;
if (className == "NXdata") {
return group.nxname;
}
}
throw std::runtime_error("No NXdata found in file");
}();
NXData dataGroup = entry.openNXData(detectorName);
// Usually for muon data, detector id = spectrum number
// If not, the optional groups "detector_index", "detector_list" and
// "detector_count" will be present to map one to the other
const bool hasDetectorMapping = dataGroup.containsDataSet("detector_index") &&
dataGroup.containsDataSet("detector_list") &&
dataGroup.containsDataSet("detector_count");
if (hasDetectorMapping) {
// Read detector IDs
try {
const auto detIndex = dataGroup.openNXInt("detector_index");
const auto detCount = dataGroup.openNXInt("detector_count");
const auto detList = dataGroup.openNXInt("detector_list");
const int nSpectra = detIndex.dim0();
for (int i = 0; i < nSpectra; ++i) {
const int start = detIndex[i];
const int nDetectors = detCount[i];
std::set<int> detIDs;
for (int jDet = 0; jDet < nDetectors; ++jDet) {
detIDs.insert(detList[start + jDet]);
}
mapping[i] = detIDs;
}
} catch (const ::NeXus::Exception &err) {
// Throw a more user-friendly message
std::ostringstream message;
message << "Failed to read detector mapping: " << err.what();
throw std::runtime_error(message.str());
}
} else {
for (int i = 0; i < nSpectra; ++i) {
mapping[i] = std::set<int>{spectrumIndex[i]};
}
}
return mapping;
}
