SoftElectronTruthDecoratorAlg.cxx

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/*
  Copyright (C) 2002-2026 CERN for the benefit of the ATLAS collaboration
*/
 
 
#include "FlavorTagDiscriminants/SoftElectronTruthDecoratorAlg.h"
#include "FlavorTagDiscriminants/TruthDecoratorHelpers.h"
 
#include "StoreGate/WriteDecorHandle.h"
#include "StoreGate/ReadDecorHandle.h"
 
#include "InDetTrackSystematicsTools/InDetTrackTruthOriginDefs.h"
 
#include "xAODEgamma/ElectronContainer.h"
#include "xAODEgamma/EgammaxAODHelpers.h"
 
#include "xAODTruth/TruthVertex.h"
#include "xAODTruth/TruthVertexContainer.h"
 
#include "TruthUtils/MagicNumbers.h"
 
namespace FlavorTagDiscriminants {
 
  SoftElectronTruthDecoratorAlg::SoftElectronTruthDecoratorAlg(
    const std::string& name, ISvcLocator* loc )
    : AthReentrantAlgorithm(name, loc) {}
 
  StatusCode SoftElectronTruthDecoratorAlg::initialize() {
    ATH_MSG_DEBUG( "Initializing " << name() << "... " );
 
    // Initialize Container keys
    ATH_MSG_DEBUG( "Initializing containers:"            );
    ATH_MSG_DEBUG( "    ** " << m_ElectronContainerKey   );
 
    ATH_CHECK( m_ElectronContainerKey.initialize() );
    ATH_CHECK( m_truthParticleContainerKey.initialize() );
 
    // Initialise accessors
    ATH_CHECK( m_acc_origin_label.initialize() );
    ATH_CHECK( m_acc_type_label.initialize() );
    ATH_CHECK( m_acc_source_label.initialize() );
    ATH_CHECK( m_acc_vertex_index.initialize() );
    ATH_CHECK( m_acc_parent_uniqueID.initialize() );
 
    // Initialise decorators
    ATH_CHECK( m_dec_origin_label.initialize() );
    ATH_CHECK( m_dec_type_label.initialize() );
    ATH_CHECK( m_dec_source_label.initialize() );
    ATH_CHECK( m_dec_vertex_index.initialize() );
    ATH_CHECK( m_dec_uniqueID.initialize() );
    ATH_CHECK( m_dec_parent_uniqueID.initialize() );
 
    ATH_CHECK( m_truthParticleLinkKey.initialize() );
    ATH_CHECK( m_classifierParticleTypeKey.initialize() );
    // ATLASRECTS-8290: this is for backward compatability, remove eventually
    if (m_use_barcode) {
      m_uidKey = "TruthParticles.barcode";
    }
    ATH_CHECK( m_uidKey.initialize() );
 
    return StatusCode::SUCCESS;
  }
 
  StatusCode SoftElectronTruthDecoratorAlg::execute(const EventContext& ctx) const {
    ATH_MSG_DEBUG( "Executing " << name() << "... " );
 
    using EC = xAOD::ElectronContainer;
 
    // read collections
    SG::ReadHandle<EC> electrons(m_ElectronContainerKey,ctx);
    ATH_CHECK( electrons.isValid() );
    ATH_MSG_DEBUG( "Retrieved " << electrons->size() << " electrons..." );
 
    // instantiate accessors
    using RDH = SG::ReadDecorHandle<xAOD::TruthParticleContainer, int>;
    RDH acc_origin_label(m_acc_origin_label, ctx);
    RDH acc_type_label(m_acc_type_label, ctx);
    RDH acc_source_label(m_acc_source_label, ctx);
    RDH acc_vertex_index(m_acc_vertex_index, ctx);
    RDH acc_parent_uniqueID(m_acc_parent_uniqueID, ctx);
 
    SG::ReadDecorHandle<xAOD::ElectronContainer, ElementLink<xAOD::TruthParticleContainer>> truthParticleLink(m_truthParticleLinkKey, ctx);
    SG::ReadDecorHandle<xAOD::TruthParticleContainer, unsigned int> classifierParticleType(m_classifierParticleTypeKey, ctx);
    SG::ReadDecorHandle<xAOD::TruthParticleContainer, int> uid(m_uidKey, ctx);
 
    // instantiate decorators
    using WDH = SG::WriteDecorHandle<EC, int>;
    WDH dec_origin_label(m_dec_origin_label, ctx);
    WDH dec_type_label(m_dec_type_label, ctx);
    WDH dec_source_label(m_dec_source_label, ctx);
    WDH dec_vertex_index(m_dec_vertex_index, ctx);
    WDH dec_uniqueID(m_dec_uniqueID, ctx);
    WDH dec_parent_uniqueID(m_dec_parent_uniqueID, ctx);
 
    std::vector<const xAOD::Electron*> el_vector(electrons->begin(), electrons->end());
    for ( const auto& electron : el_vector ) {
 
      // get the linked truth particle
      const auto truth_link = truthParticleLink(*electron);
 
      if (!truth_link || !truth_link.isValid()) {
        // if the truth link is broken, assume PU
        dec_origin_label(*electron) = InDet::ExclusiveOrigin::Pileup;
        dec_type_label(*electron) = TruthDecoratorHelpers::TruthType::Label::NoTruth;
        dec_source_label(*electron) = TruthDecoratorHelpers::TruthSource::Label::NoTruth;
        dec_vertex_index(*electron) = -2;
        dec_uniqueID(*electron) = HepMC::UNDEFINED_ID;
        dec_parent_uniqueID(*electron) = HepMC::UNDEFINED_ID;
      } else {
        const auto *truth = *truth_link;
        int electron_type = classifierParticleType(*truth);
 
        if (m_valid_types.count(electron_type)) {
          dec_origin_label(*electron) = acc_origin_label(*truth);
        }
        else {
          dec_origin_label(*electron) = InDet::ExclusiveOrigin::Fake;
        }
 
        dec_vertex_index(*electron) = acc_vertex_index(*truth);
        dec_type_label(*electron) = acc_type_label(*truth);
        dec_source_label(*electron) = acc_source_label(*truth);
        // ATLASRECTS-8290: replace uid with ->uid() eventually
        dec_uniqueID(*electron) = uid(*truth);
        dec_parent_uniqueID(*electron) = acc_parent_uniqueID(*truth);
      }
    }
    return StatusCode::SUCCESS;
  }
}