/data/refman/pasoursint/CMSSW_4_1_8_patch12/src/Validation/RecoParticleFlow/plugins/GenJetClosestMatchSelectorDefinition.h

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#ifndef PhysicsTools_PFCandProducer_GenJetClosestMatchSelectorDefinition
#define PhysicsTools_PFCandProducer_GenJetClosestMatchSelectorDefinition

#include "DataFormats/JetReco/interface/GenJet.h"

#include "DataFormats/Math/interface/deltaR.h"

#include <iostream>

struct GenJetClosestMatchSelectorDefinition {


  typedef reco::GenJetCollection collection;
  typedef edm::Handle< collection > HandleToCollection;
  typedef std::vector< reco::GenJet *> container;
  typedef container::const_iterator const_iterator;

  GenJetClosestMatchSelectorDefinition ( const edm::ParameterSet & cfg ) {

    matchTo_ = cfg.getParameter< edm::InputTag >( "MatchTo" ); 
  }
  
  const_iterator begin() const { return selected_.begin(); }

  const_iterator end() const { return selected_.end(); }

  void select( const HandleToCollection & hc, 
               const edm::Event & e,
               const edm::EventSetup& s) 
  {
           
    selected_.clear();
    
    edm::Handle< edm::View<reco::Candidate> > matchCandidates; 
    e.getByLabel( matchTo_, matchCandidates);


    unsigned key=0;

    //    std::cout<<"number of candidates "<<matchCandidates->size()<<std::endl;

    typedef edm::View<reco::Candidate>::const_iterator IC;
    for( IC ic = matchCandidates->begin(); 
         ic!= matchCandidates->end(); ++ic ) {
      
      double eta2 = ic->eta();
      double phi2 = ic->phi();

      //      std::cout<<"cand "<<eta2<<" "<<phi2<<std::endl; 

      
      // look for the closest gen jet
      double deltaR2Min = 9999;
      collection::const_iterator closest = hc->end();
      for( collection::const_iterator genjet = hc->begin(); 
           genjet != hc->end();
           ++genjet, ++key) {
        
        reco::GenJetRef genJetRef(hc, key);
      
        // is it matched? 
        
        double eta1 = genjet->eta();
        double phi1 = genjet->phi();
        
        
        double deltaR2 = reco::deltaR2(eta1, phi1, eta2, phi2);
        
        // std::cout<<"  genjet "<<eta1<<" "<<phi1<<" "<<deltaR2<<std::endl;
        
        // cut should be a parameter
        if( deltaR2<deltaR2Min ) {
          deltaR2Min = deltaR2;
          closest = genjet;
        }
      }

      if(deltaR2Min<0.01 ) {
        // std::cout<<deltaR2Min<<std::endl;
        selected_.push_back( new reco::GenJet(*closest) );
      }
    } // end collection iteration

    // std::cout<<selected_.size()<<std::endl;
  } // end select()

  size_t size() const { return selected_.size(); }

private:
  container selected_;  
  edm::InputTag  matchTo_;
};

#endif