PFTrackSelector.cxx

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/*
  Copyright (C) 2002-2022 CERN for the benefit of the ATLAS collaboration
*/
#include "eflowRec/eflowTrackExtrapolatorBaseAlgTool.h"
#include "PFTrackSelector.h"
#include "StoreGate/ReadCondHandleKey.h"
#include "xAODEgamma/ElectronxAODHelpers.h"
#include "GaudiKernel/SystemOfUnits.h"
 
constexpr float invGeV = 1./CLHEP::GeV;
 
PFTrackSelector::PFTrackSelector(const std::string& name, ISvcLocator* pSvcLocator):
  AthReentrantAlgorithm(name, pSvcLocator)
{
}
 
StatusCode PFTrackSelector::initialize(){
 
  ATH_CHECK(m_theTrackExtrapolatorTool.retrieve());  
  ATH_CHECK(m_trackSelectorTool.retrieve());
 
  ATH_CHECK(m_tracksReadHandleKey.initialize());
  ATH_CHECK(m_vertexKey.initialize());
 
  // Optional readhandlekeys for electrons and muons
  if(!m_electronsReadHandleKey.key().empty()) {
    ATH_CHECK(m_electronsReadHandleKey.initialize());
  }
  if(!m_muonsReadHandleKey.key().empty()) {
    ATH_CHECK(m_muonsReadHandleKey.initialize());
  }
 
  ATH_CHECK(m_eflowRecTracksWriteHandleKey.initialize());
  
  if (!m_monTool.empty()) ATH_CHECK(m_monTool.retrieve());
 
  return StatusCode::SUCCESS;
 
}
 
StatusCode PFTrackSelector::execute(const EventContext& ctx) const{
  // Monitor the time taken to execute the alg
  auto t_exec = Monitored::Timer<std::chrono::milliseconds>( "TIME_execute" );
    Monitored::ScopedTimer execution_time(t_exec);
  auto N_tracks = Monitored::Scalar( "N_tracks", 0 );
  auto eta_track = Monitored::Scalar( "eta_track", 0. );
  auto pt_track = Monitored::Scalar( "pt_track", 0. );
 
  SG::WriteHandle<eflowRecTrackContainer> eflowRecTracksWriteHandle(m_eflowRecTracksWriteHandleKey, ctx);
  ATH_CHECK(eflowRecTracksWriteHandle.record(std::make_unique<eflowRecTrackContainer>()));
 
  /* Verify the read handle has a valid pointer, and if not return */
  SG::ReadHandle<xAOD::TrackParticleContainer> tracksReadHandle(m_tracksReadHandleKey, ctx);
  if (!tracksReadHandle.isValid()) {
    ATH_MSG_WARNING("Can not retrieve xAOD::TrackParticleContainer with name: " << tracksReadHandle.key());
    return StatusCode::FAILURE;
  }
 
  /* Do the track selection for tracks to be used in all of the following steps: */
 
  for (const auto *thisTrack : *tracksReadHandle){
 
    if (!thisTrack){
      ATH_MSG_WARNING("Have invalid pointer to xAOD::TrackParticle");
      continue; 
    }
 
    ATH_MSG_DEBUG("Have track with E, pt, eta and phi of " << thisTrack->e() << ", " << thisTrack->pt() << ", "
                                                           << thisTrack->eta() << " and " << thisTrack->phi());
 
 
    bool rejectTrack(!selectTrack(*thisTrack));
 
    bool isElectron = this->isElectron(thisTrack);
    bool isMuon = this->isMuon(thisTrack);
    ATH_MSG_DEBUG("isElectron is " << isElectron << " and isMuon is " << isMuon);
    if (isElectron || isMuon) rejectTrack = true;
 
    ATH_MSG_DEBUG("rejectTrack is " << rejectTrack);
    
    const xAOD::TrackParticleContainer* trkcont{nullptr};
    if (!rejectTrack) {
      // Monitor the time per selected track
      auto t_track = Monitored::Timer<std::chrono::microseconds>( "TIME_track" );
      eta_track = thisTrack->eta();
      pt_track = thisTrack->pt() * invGeV;
      if(trkcont==nullptr) {
        trkcont = static_cast<const xAOD::TrackParticleContainer*>(thisTrack->container());
      }
 
      /* Create the eflowRecCluster and put it in the container */
      unsigned int trackIndex  = thisTrack->index();
      std::unique_ptr<eflowRecTrack> thisEFRecTrack  = std::make_unique<eflowRecTrack>(ElementLink<xAOD::TrackParticleContainer>(trkcont, trackIndex), m_theTrackExtrapolatorTool);
      thisEFRecTrack->setTrackId(trackIndex);
      eflowRecTracksWriteHandle->push_back(std::move(thisEFRecTrack));
 
      // Fill histogram
      auto mon_trk = Monitored::Group(m_monTool, t_track, eta_track, pt_track);
    }
  }
 
  std::sort(eflowRecTracksWriteHandle->begin(), eflowRecTracksWriteHandle->end(), eflowRecTrack::SortDescendingPt());
 
  N_tracks = eflowRecTracksWriteHandle->size();
  auto mon_exectime = Monitored::Group(m_monTool, t_exec, N_tracks);
  return StatusCode::SUCCESS;
}
 
StatusCode PFTrackSelector::finalize(){return StatusCode::SUCCESS;}
 
bool
PFTrackSelector::selectTrack(const xAOD::TrackParticle& track) const
{
  // We pass a null xAOD::Vertex pointer to accept here, the vertex is only needed if z0 cuts are applied (which they
  // are not)
  if (track.pt() * 0.001 < m_upperTrackPtCut){
    return static_cast<bool>(m_trackSelectorTool->accept(track, nullptr));
  }
  else
    return false;
}
 
bool PFTrackSelector::isElectron(const xAOD::TrackParticle* track) const{
 
  if (m_electronsReadHandleKey.key().empty())
    return false;
 
  SG::ReadHandle<xAOD::ElectronContainer> electronsReadHandle(m_electronsReadHandleKey);
  if (electronsReadHandle.isValid()) {
 
    for (const auto* thisElectron : *electronsReadHandle) {
 
      if (thisElectron) {
        unsigned int nTrack = thisElectron->nTrackParticles();
 
        if (0 != nTrack) {
          const xAOD::TrackParticle* origTrack = xAOD::EgammaHelpers::getOriginalTrackParticle(thisElectron);
          if (origTrack) {
            if (track == origTrack) {
              return true;
            }
          } // if valid track pointer
          else
            ATH_MSG_WARNING("Electron object map has NULL pointer to original TrackParticle");
        } // if has a track
        else
          ATH_MSG_WARNING("Electron object has " << nTrack << " tracks");
      } // if valid pointer
      else
        ATH_MSG_WARNING("Electron is a NULL pointer");
    } // electron loop
  } else
    ATH_MSG_WARNING("Invalid ReadHandle for electrons with key: " << electronsReadHandle.key());
 
  return false;
}
 
bool
PFTrackSelector::isMuon(const xAOD::TrackParticle* track) const
{
 
  if (m_muonsReadHandleKey.key().empty())
    return false;
 
  SG::ReadHandle<xAOD::MuonContainer> muonsReadHandle(m_muonsReadHandleKey);
  if (muonsReadHandle.isValid()) {
 
    for (const auto* theMuon : *muonsReadHandle) {
      if (theMuon) {
        ATH_MSG_DEBUG("Considering muon in isMuon with e,pt, eta and phi of "
                      << theMuon->e() << ", " << theMuon->pt() << ", " << theMuon->eta() << " and " << theMuon->phi());
        const ElementLink<xAOD::TrackParticleContainer>& theLink = theMuon->inDetTrackParticleLink();
        if (theLink.isValid()) {
          const xAOD::TrackParticle* ID_track = *theLink;
          if (ID_track) {
            if (track == ID_track){
              return true;
            }
          } else
            ATH_MSG_WARNING("This muon has a NULL pointer to the track");
        } else
          ATH_MSG_WARNING("This muon has an invalid link to the track");
      } // if muon pointer is valid
      else
        ATH_MSG_WARNING("This muon is a NULL pointer");
    } // muon loop
  } else
    ATH_MSG_WARNING("Invalid ReadHandle for muons with key: " << muonsReadHandle.key());
 
  return false;
}