/afs/cern.ch/work/a/aaltunda/public/www/CMSSW_5_3_14/src/RecoParticleFlow/PFTracking/plugins/PFConversionProducer.cc

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#include <memory>
#include "RecoParticleFlow/PFTracking/plugins/PFConversionProducer.h"
#include "RecoParticleFlow/PFTracking/interface/PFTrackTransformer.h"
#include "DataFormats/ParticleFlowReco/interface/PFConversionFwd.h"
#include "DataFormats/ParticleFlowReco/interface/PFConversion.h"
#include "DataFormats/VertexReco/interface/VertexFwd.h"
#include "DataFormats/VertexReco/interface/Vertex.h"
#include "TrackingTools/PatternTools/interface/Trajectory.h"
#include "FWCore/Framework/interface/ESHandle.h"
#include "MagneticField/Engine/interface/MagneticField.h"
#include "MagneticField/Records/interface/IdealMagneticFieldRecord.h"
#include "DataFormats/Common/interface/RefToBase.h"
#include "CommonTools/Statistics/interface/ChiSquaredProbability.h"
#include "RecoEgamma/EgammaTools/interface/ConversionLikelihoodCalculator.h"
#include "RecoEgamma/EgammaPhotonAlgos/interface/ConversionHitChecker.h"
#include "TrackingTools/TransientTrack/interface/TransientTrackBuilder.h"
#include "TrackingTools/Records/interface/TransientTrackRecord.h"
#include "TrackingTools/IPTools/interface/IPTools.h"

typedef  std::multimap<unsigned, std::vector<unsigned> > BlockMap;
using namespace std;
using namespace edm;


PFConversionProducer::PFConversionProducer(const ParameterSet& iConfig):
  pfTransformer_(0)
{
  produces<reco::PFRecTrackCollection>();
  produces<reco::PFConversionCollection>();

  pfConversionContainer_ = 
    iConfig.getParameter< InputTag >("conversionCollection");
  vtx_h=iConfig.getParameter<edm::InputTag>("PrimaryVertexLabel");
}

PFConversionProducer::~PFConversionProducer()
{
  delete pfTransformer_;
}

void
PFConversionProducer::produce(Event& iEvent, const EventSetup& iSetup)
{
  
  //create the empty collections 
  auto_ptr< reco::PFConversionCollection > 
    pfConversionColl (new reco::PFConversionCollection);
  auto_ptr< reco::PFRecTrackCollection > 
    pfRecTrackColl (new reco::PFRecTrackCollection);
  
  edm::ESHandle<TransientTrackBuilder> builder;
  iSetup.get<TransientTrackRecord>().get("TransientTrackBuilder", builder);
  TransientTrackBuilder thebuilder = *(builder.product());
  reco::PFRecTrackRefProd pfTrackRefProd = iEvent.getRefBeforePut<reco::PFRecTrackCollection>();
  Handle<reco::ConversionCollection> convCollH;
  iEvent.getByLabel(pfConversionContainer_, convCollH);
  
  const reco::ConversionCollection& convColl = *(convCollH.product());
  
  Handle<reco::TrackCollection> trackColl;
  iEvent.getByLabel(pfTrackContainer_, trackColl);
  Handle<reco::VertexCollection> vertex;
  iEvent.getByLabel(vtx_h, vertex);
  //Find PV for IP calculation, if there is no PV in collection than use dummy 
  reco::Vertex dummy;
  const reco::Vertex* pv=&dummy;    
  if (vertex.isValid()) 
    {
      pv = &*vertex->begin();
    } 
  else 
    { // create a dummy PV
      reco::Vertex::Error e;
      e(0, 0) = 0.0015 * 0.0015;
      e(1, 1) = 0.0015 * 0.0015;
      e(2, 2) = 15. * 15.;
      reco::Vertex::Point p(0, 0, 0);
      dummy = reco::Vertex(p, e, 0, 0, 0);   
    } 
  
  int idx = 0; //index of track in PFRecTrack collection 
  multimap<unsigned int, unsigned int> trackmap; //Map of Collections and tracks  
  std::vector<unsigned int> conv_coll(0);
   
  // CLEAN CONVERSION COLLECTION FOR DUPLICATES     
  for( unsigned int icoll1=0; icoll1 < convColl.size(); icoll1++) 
    { 
      if (( !convColl[icoll1].quality(reco::Conversion::arbitratedMergedEcalGeneral)) || (!convColl[icoll1].quality(reco::Conversion::highPurity))) continue;
      
      bool greater_prob=false;
      std::vector<edm::RefToBase<reco::Track> > tracksRefColl1 = convColl[icoll1].tracks();      
      for(unsigned it1 = 0; it1 < tracksRefColl1.size(); it1++)
        {
          reco::TrackRef trackRef1 = (tracksRefColl1[it1]).castTo<reco::TrackRef>();
         
          for( unsigned int icoll2=0; icoll2 < convColl.size(); icoll2++) 
            {
              if(icoll1==icoll2)continue;
              if (( !convColl[icoll2].quality(reco::Conversion::arbitratedMergedEcalGeneral)) || (!convColl[icoll2].quality(reco::Conversion::highPurity))) continue;
              std::vector<edm::RefToBase<reco::Track> > tracksRefColl2 = convColl[icoll2].tracks();     
              for(unsigned it2 = 0; it2 < tracksRefColl2.size(); it2++)
                {
                  reco::TrackRef trackRef2 = (tracksRefColl2[it2]).castTo<reco::TrackRef>();
                  double like1=-999;
                  double like2=-999;
                  //number of shared hits
                  int shared=0;
                  for(trackingRecHit_iterator iHit1=trackRef1->recHitsBegin(); iHit1!=trackRef1->recHitsEnd(); iHit1++) 
                    {
                      const TrackingRecHit *h_1=iHit1->get();
                      if(h_1->isValid()){                 
                        for(trackingRecHit_iterator iHit2=trackRef2->recHitsBegin(); iHit2!=trackRef2->recHitsEnd(); iHit2++)
                          {
                            const TrackingRecHit *h_2=iHit2->get();
                            if(h_2->isValid() && h_1->sharesInput(h_2, TrackingRecHit::some))shared++;//count number of shared hits
                          }
                      }
                    }             
                  float frac=0;
                  //number of valid hits in tracks that are duplicates
                  float size1=trackRef1->found();
                  float size2=trackRef2->found();
                  //divide number of shared hits by the total number of hits for the track with less hits
                  if(size1>size2)frac=(double)shared/size2;
                  else frac=(double)shared/size1;
                  if(frac>0.9)
                    {
                      like1=ChiSquaredProbability(convColl[icoll1].conversionVertex().chi2(), convColl[icoll1].conversionVertex().ndof());
                      like2=ChiSquaredProbability(convColl[icoll2].conversionVertex().chi2(), convColl[icoll2].conversionVertex().ndof());
                    }
                  if(like2>like1)
                    {greater_prob=true;  break;}
                }//end loop over tracks in collection 2

              if(greater_prob)break; //if a duplicate track is found in a collection with greater Chi^2 probability for Vertex fit then break out of comparison loop
            }//end loop over collection 2 checking
          if(greater_prob)break;//if a duplicate track is found in a collection with greater Chi^2 probability for Vertex fit then one does not need to check the other track the collection will not be stored
        } //end loop over tracks in collection 1
      if(!greater_prob)conv_coll.push_back(icoll1);
    }//end loop over collection 1
  
  //Finally fill empty collections
  for(unsigned iColl=0; iColl<conv_coll.size(); iColl++)
    {
      unsigned int collindex=conv_coll[iColl];
      //std::cout<<"Filling this collection"<<collindex<<endl;
      std::vector<reco::PFRecTrackRef> pfRecTkcoll;     
      
      std::vector<edm::RefToBase<reco::Track> > tracksRefColl = convColl[collindex].tracks();     
      // convert the secondary tracks
      for(unsigned it = 0; it < tracksRefColl.size(); it++)
        {
          reco::TrackRef trackRef = (tracksRefColl[it]).castTo<reco::TrackRef>();      
          reco::PFRecTrack pfRecTrack( trackRef->charge(), 
                                       reco::PFRecTrack::KF, 
                                       trackRef.key(), 
                                       trackRef );             
          //std::cout<<"Track Pt "<<trackRef->pt()<<std::endl;
          Trajectory FakeTraj;
          bool valid = pfTransformer_->addPoints( pfRecTrack, *trackRef, FakeTraj);
          if(valid) 
            {
              double stip=-999;
              const reco::PFTrajectoryPoint& atECAL=pfRecTrack.extrapolatedPoint(reco::PFTrajectoryPoint::ECALEntrance);
              //if extrapolation to ECAL is valid then calculate STIP
              if(atECAL.isValid())
                {
                  GlobalVector direction(pfRecTrack.extrapolatedPoint(reco::PFTrajectoryPoint::ECALEntrance).position().x(),
                                         pfRecTrack.extrapolatedPoint(reco::PFTrajectoryPoint::ECALEntrance).position().y(), 
                                         pfRecTrack.extrapolatedPoint(reco::PFTrajectoryPoint::ECALEntrance).position().z());
                  stip = IPTools::signedTransverseImpactParameter(thebuilder.build(*trackRef), direction, *pv).second.significance();
                }
              pfRecTrack.setSTIP(stip);     
              pfRecTkcoll.push_back(reco::PFRecTrackRef( pfTrackRefProd, idx++));         
              pfRecTrackColl->push_back(pfRecTrack);        
            }
        }//end loop over tracks
      //store reference to the Conversion collection
      reco::ConversionRef niRef(convCollH, collindex);
      pfConversionColl->push_back( reco::PFConversion( niRef, pfRecTkcoll ));
    }//end loop over collections
  iEvent.put(pfRecTrackColl);
  iEvent.put(pfConversionColl);    
}
  
// ------------ method called once each job just before starting event loop  ------------
void 
PFConversionProducer::beginRun(edm::Run& run,
                               const EventSetup& iSetup)
{
  ESHandle<MagneticField> magneticField;
  iSetup.get<IdealMagneticFieldRecord>().get(magneticField);
  pfTransformer_= new PFTrackTransformer(math::XYZVector(magneticField->inTesla(GlobalPoint(0,0,0))));
  pfTransformer_->OnlyProp();
}

// ------------ method called once each job just after ending the event loop  ------------
void 
PFConversionProducer::endRun() {
  delete pfTransformer_;
}