/data/refman/pasoursint/CMSSW_5_3_10/src/DQMOffline/PFTau/interface/Matchers.h

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#ifndef __RecoParticleFlow_Benchmark_Matchers__
#define __RecoParticleFlow_Benchmark_Matchers__

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

#include <vector>
#include <iostream>

namespace PFB {

   
  template< typename C, typename M>
    void match(const C& candCollection,
               const M& matchedCandCollection, 
               std::vector<int>& matchIndices,
               bool  matchCharge = false, 
               float dRMax=-1)  {
    
    // compute distance to each candidate in the matchedCandCollection. 
  
    float dR2Max = 0;
    if(dRMax>0) dR2Max = dRMax*dRMax;

    matchIndices.clear();
    matchIndices.resize( candCollection.size(), -1);
    
    for( unsigned i=0; i<candCollection.size(); ++i) {
      
      static const double bigNumber = 1e14;
      double dR2min = bigNumber;
      int jMin = -1;
      for( unsigned jm=0; jm<matchedCandCollection.size(); ++jm) {
        
        if( matchCharge && 
            candCollection[i].charge()!=matchedCandCollection[jm].charge() ) 
          continue;

        double dR2 = reco::deltaR2( candCollection[i],
                                    matchedCandCollection[jm] );
        
        if( dR2<dR2min ) {
          dR2min = dR2;
          jMin = jm;
        }
      }
      
      if( (dR2Max>0 && dR2min < dR2Max) || dRMax<=0 ) {
        matchIndices[i] = jMin; 
/*      std::cout<<"match "<<dR2min<<std::endl;  */
      }
      // store the closest match, no cut on deltaR. 
    }
  }







}
   

#endif