CaloCalibClusterTruthAttributerTool.cxx

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/*
   Copyright (C) 2002-2025 CERN for the benefit of the ATLAS collaboration
*/
 
#include "CaloCalibHitRec/CaloCalibClusterTruthAttributerTool.h"
 
CaloCalibClusterTruthAttributerTool::CaloCalibClusterTruthAttributerTool(const std::string& type, const std::string& name,  const IInterface* parent) : base_class(type,name,parent) {
}
 
CaloCalibClusterTruthAttributerTool::~CaloCalibClusterTruthAttributerTool()= default;
 
StatusCode CaloCalibClusterTruthAttributerTool::calculateTruthEnergies(const xAOD::CaloCluster& theCaloCluster, unsigned int numTruthParticles, const std::map<Identifier,std::vector<const CaloCalibrationHit*> >& identifierToCaloHitMap, std::vector<std::pair<unsigned int, double > >& truthIDTrueCalHitEnergy) const{
 
  ATH_MSG_DEBUG("In calculateTruthEnergies");
 
  const CaloClusterCellLink* theCellLinks = theCaloCluster.getCellLinks();
 
  if (!theCellLinks) {
    ATH_MSG_ERROR("A CaloCluster has no CaloClusterCellLinks");
    return StatusCode::FAILURE;
  }  
  
  std::map<unsigned int, double> truthIDTruePtMap;
 
  //Loop on calorimeter cells to sum up the truth energies of the truth particles.    
  CaloClusterCellLink::const_iterator firstCell = theCellLinks->begin();
  CaloClusterCellLink::const_iterator lastCell   = theCellLinks->end();
 
  for (; firstCell != lastCell; ++firstCell) {
    const CaloCell* thisCaloCell = (*firstCell);
    
    if (!thisCaloCell){
      ATH_MSG_WARNING("Have invalid pointer to CaloCell");
      continue;
    }
 
    //get the unique calorimeter cell identifier
    Identifier cellID = thisCaloCell->ID();
 
    //get the weight of the cell
    double cellWeight = firstCell.weight();
    
    //look up the calibration hit that corresponds to this calorimeter cell - we use find because not all calorimeter cells will have calibration hits
    std::map<Identifier,std::vector<const CaloCalibrationHit*> >::const_iterator identifierToCaloHitMapIterator = identifierToCaloHitMap.find(cellID);
    if (identifierToCaloHitMap.end() == identifierToCaloHitMapIterator) continue;
    std::vector<const CaloCalibrationHit*> theseCalibrationHits = (*identifierToCaloHitMapIterator).second;
 
    for (const auto *thisCalibrationHit : theseCalibrationHits){
      const int truthID = HepMC::uniqueID(thisCalibrationHit);
      double thisCalHitTruthEnergy = thisCalibrationHit->energyEM() + thisCalibrationHit->energyNonEM();
      if (true == m_fullTruthEnergy) thisCalHitTruthEnergy += (thisCalibrationHit->energyEscaped() + thisCalibrationHit->energyInvisible());
 
      //This only makes sense to use for clusters that are NOT calibrated
      //If the cluster is calibrated this weight includes a calibration factor
      //which is not relevant for truth information.
      //For uncalibrated clusters it can contain a gemetrical weight
      //and also a weight due to pflow reweighting of a cell energy
      if (m_useCellWeights) thisCalHitTruthEnergy *= cellWeight;
 
      if (truthID > HepMC::UNDEFINED_ID) {
        truthIDTruePtMap[truthID] += thisCalHitTruthEnergy;
      }
      
    }//calibration hit loop
    
  }//loop on calorimeter cells to sum up truth energies
 
  //now create a vector with the same information as the map, which we can then sort
  std::vector<std::pair<unsigned int, double > > truthIDTruePtPairs;
 
  truthIDTruePtPairs.reserve(truthIDTruePtMap.size());
  for (const auto& thisEntry : truthIDTruePtMap) truthIDTruePtPairs.emplace_back(thisEntry);
 
  //sort vector by calibration hit truth energy
  std::sort(truthIDTruePtPairs.begin(),truthIDTruePtPairs.end(),[]( std::pair<unsigned int, double> a, std::pair<unsigned int, double> b) -> bool {return a.second > b.second;} );
 
  //store the truthID and truth energy of the top numTruthParticles truth particles
  if (numTruthParticles > truthIDTruePtPairs.size()) numTruthParticles = truthIDTruePtPairs.size();
  for ( unsigned int counter = 0; counter < numTruthParticles; counter++) truthIDTrueCalHitEnergy.push_back(truthIDTruePtPairs[counter]);
 
  for (const auto& thisPair : truthIDTrueCalHitEnergy) ATH_MSG_DEBUG("Truncated loop 2: truthID and true energy are " << thisPair.first << " and " << thisPair.second << " for cluster with e, eta of " << theCaloCluster.e() << " and " << theCaloCluster.eta() );
 
  return StatusCode::SUCCESS;
  
}