xAODTruthParticleSlimmerMuon.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 "GeneratorFilters/xAODTruthParticleSlimmerMuon.h"
 
xAODTruthParticleSlimmerMuon::xAODTruthParticleSlimmerMuon(const std::string &name, ISvcLocator *svcLoc)
    : AthAlgorithm(name, svcLoc)
{
}
 
StatusCode xAODTruthParticleSlimmerMuon::initialize()
{
    ATH_CHECK(m_xaodTruthEventContainerName.initialize());
    ATH_CHECK(m_xaodTruthParticleContainerNameMuon.initialize());
    ATH_MSG_INFO("xAOD output TruthParticleContainerNameMuon name = " << m_xaodTruthParticleContainerNameMuon.key());
    ATH_MSG_INFO("xAOD input xAODTruthEventContainerName name = " << m_xaodTruthEventContainerName.key());
    return StatusCode::SUCCESS;
}
 
StatusCode xAODTruthParticleSlimmerMuon::execute(const EventContext& ctx)
{
  // If the containers already exists then assume that nothing needs to be done
  if (evtStore()->contains<xAOD::TruthParticleContainer>(m_xaodTruthParticleContainerNameMuon.key()))
    {
      ATH_MSG_WARNING("xAOD Muon Truth Particles are already available in the event");
      return StatusCode::SUCCESS;
    }
 
    // Create new output container
    SG::WriteHandle<xAOD::TruthParticleContainer> xTruthParticleContainerMuon(m_xaodTruthParticleContainerNameMuon, ctx);
    ATH_CHECK(xTruthParticleContainerMuon.record(std::make_unique<xAOD::TruthParticleContainer>(), std::make_unique<xAOD::TruthParticleAuxContainer>()));
    ATH_MSG_INFO("Recorded TruthParticleContainerMuon with key: " << m_xaodTruthParticleContainerNameMuon.key());
 
    // Retrieve full TruthEventContainer container
    SG::ReadHandle<xAOD::TruthEventContainer> xTruthEventContainer(m_xaodTruthEventContainerName, ctx);
    if (!xTruthEventContainer.isValid()) {
      ATH_MSG_ERROR("Could not retrieve xAOD::TruthEventContainer with key:" <<
                    m_xaodTruthEventContainerName.key());
      return StatusCode::FAILURE;
    }
    // Set up decorators if needed
    xAOD::TruthEventContainer::const_iterator itr;
    for (itr = xTruthEventContainer->begin(); itr!=xTruthEventContainer->end(); ++itr) {
        
        std::vector<int> uniqueID_list;  
        int zero_uniqueID=0;
        int dup_uniqueID=0;
        unsigned int nPart = (*itr)->nTruthParticles();
        for (unsigned int iPart = 0; iPart < nPart; ++iPart) {
            const xAOD::TruthParticle* theParticle =  (*itr)->truthParticle(iPart);
             
            int my_uniqueID = HepMC::uniqueID(theParticle);
            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 Muons
            if (MC::isStable(theParticle) && MC::isMuon(theParticle))
            {
                xAOD::TruthParticle *xTruthParticle = new xAOD::TruthParticle();
                xTruthParticleContainerMuon->push_back( xTruthParticle );
                // Fill with numerical content
                *xTruthParticle=*theParticle;
            }   
        }
    ATH_MSG_INFO("Found "<< zero_uniqueID << " uniqueID-zero partciles and " << dup_uniqueID << " duplicates");
    }
 
    return StatusCode::SUCCESS;
}