xAODTruthParticleSlimmerLightLepton.cxx

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/*
  Copyright (C) 2002-2025 CERN for the benefit of the ATLAS collaboration
*/
 
#include "AthenaKernel/errorcheck.h"
#include "AthLinks/ElementLink.h"
 
#include "GeneratorObjects/xAODTruthParticleLink.h"
#include "TruthUtils/HepMCHelpers.h"
 
#include "GaudiKernel/MsgStream.h"
#include "GaudiKernel/DataSvc.h"
#include "GaudiKernel/PhysicalConstants.h"
 
#include "xAODTruth/TruthParticle.h"
#include "xAODTruth/TruthParticleContainer.h"
#include "xAODTruth/TruthParticleAuxContainer.h"
 
#include "xAODTruth/TruthEvent.h"
#include "xAODTruth/TruthEventContainer.h"
 
#include "GeneratorFilters/xAODTruthParticleSlimmerLightLepton.h"
 
xAODTruthParticleSlimmerLightLepton::xAODTruthParticleSlimmerLightLepton(const std::string &name, ISvcLocator *svcLoc)
    : AthReentrantAlgorithm(name, svcLoc)
{
}
 
StatusCode xAODTruthParticleSlimmerLightLepton::initialize()
{   
    ATH_CHECK(m_xaodTruthEventContainerNameReadHandleKey.initialize());
    ATH_CHECK(m_xaodTruthParticleContainerNameLightLeptonKey.initialize());
    return StatusCode::SUCCESS;
}
 
StatusCode xAODTruthParticleSlimmerLightLepton::execute(const EventContext& context) const
{
    // If the containers already exists then assume that nothing needs to be done
    if (evtStore()->contains<xAOD::TruthParticleContainer>(m_xaodTruthParticleContainerNameLightLeptonKey.key()))
    {
        ATH_MSG_WARNING("xAOD LightLeptons Truth Particles are already available in the event");
        return StatusCode::SUCCESS;
    }
 
    // Create new output container
    SG::WriteHandle<xAOD::TruthParticleContainer> xTruthParticleContainerLightLepton(m_xaodTruthParticleContainerNameLightLeptonKey, context);
    ATH_CHECK(xTruthParticleContainerLightLepton.record(std::make_unique<xAOD::TruthParticleContainer>(), std::make_unique<xAOD::TruthParticleAuxContainer>()));
        
    SG::ReadHandle<xAOD::TruthEventContainer> xTruthEventContainerReadHandle(m_xaodTruthEventContainerNameReadHandleKey, context);
    if (!xTruthEventContainerReadHandle.isValid()) {
      ATH_MSG_ERROR("Could not retrieve xAOD::TruthEventContainer with key:" << 
            m_xaodTruthEventContainerNameReadHandleKey.key());
      return StatusCode::FAILURE;
    }
 
    xAOD::TruthEventContainer::const_iterator itr;
    for (itr = xTruthEventContainerReadHandle->begin(); itr!=xTruthEventContainerReadHandle->end(); ++itr) {
 
        unsigned int nPart = (*itr)->nTruthParticles();
        std::vector<int> uniqueID_list;
        int zero_uniqueID=0;
        int dup_uniqueID=0;
 
        for (unsigned int iPart = 0; iPart < nPart; ++iPart) {
            const xAOD::TruthParticle* particle =  (*itr)->truthParticle(iPart);
    
            int my_uniqueID = HepMC::uniqueID(particle);
            if ( my_uniqueID == HepMC::UNDEFINED_ID ) {
                zero_uniqueID++;
                continue;
            }
           bool found = false;
           if (uniqueID_list.size() > 0){
             found = (std::find(uniqueID_list.begin(), uniqueID_list.end(), my_uniqueID) != uniqueID_list.end());
             if(found) {
                       dup_uniqueID++; 
                       continue;}
           }
           uniqueID_list.push_back(my_uniqueID);
            
 
            //Save stable Electrons & Muons
            if (MC::isStable(particle) && (MC::isElectron(particle) || MC::isMuon(particle)) )
            {
                xAOD::TruthParticle *xTruthParticle = new xAOD::TruthParticle();
                xTruthParticleContainerLightLepton->push_back( xTruthParticle );
 
                // Fill with numerical content
                *xTruthParticle=*particle;
            }
            if (zero_uniqueID != 0 || dup_uniqueID != 0) ATH_MSG_INFO("Found " << zero_uniqueID << " uniqueID 0 particles and " <<dup_uniqueID << "duplicated");
        }
 
    }
 
    return StatusCode::SUCCESS;
}