/afs/cern.ch/work/a/aaltunda/public/www/CMSSW_6_2_7/src/DataFormats/HepMCCandidate/src/FlavorHistoryEvent.cc

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#include "DataFormats/HepMCCandidate/interface/FlavorHistoryEvent.h"
#include "TLorentzVector.h"

#include <iostream>

using namespace reco;
using namespace std;

// Loop over flavor histories, count number of genjets with
// flavor b, c, or l
void FlavorHistoryEvent::cache()
{

  bool verbose = false;
  
  if ( verbose ) cout << "----- Caching Flavor History Event  -----" << endl;
  // Set cached to false
  cached_ = false;
  nb_ = nc_ = 0;
  highestFlavor_ = 0;
  dR_ = 0.0;
  flavorSource_ = FlavorHistory::FLAVOR_NULL;

  // get list of flavor --> type --> dR.
  // Will sort this later to determine event classification
  vector<helpers::FlavorHistoryEventHelper> classification;

  // get iterators to the history vector
  const_iterator i = histories_.begin(),
    ibegin = histories_.begin(),
    iend = histories_.end();
  // loop over the history vector and count the number of 
  // partons of flavors "b" and "c" that have a matched genjet.
  for ( ; i != iend; ++i ) {
    FlavorHistory const & flavHist = *i;
    if ( verbose ) cout << "  Processing flavor history: " << i - ibegin << " = " << endl << flavHist << endl;
    CandidatePtr const & parton = flavHist.parton();
    flavor_type flavorSource = flavHist.flavorSource();

    // Now examine the matched jets to see what the classification should be.
    int pdgId = -1;
    if ( parton.isNonnull() ) pdgId = abs(parton->pdgId());
    ShallowClonePtrCandidate const & matchedJet = flavHist.matchedJet();
    // Only count events with a matched genjet
    if ( matchedJet.masterClonePtr().isNonnull() ) {
      TLorentzVector p41 ( matchedJet.px(), matchedJet.py(), matchedJet.pz(), matchedJet.energy() );
      if ( pdgId == 5 ) nb_++;
      if ( pdgId == 4 ) nc_++;

      // Get the sister genjet
      ShallowClonePtrCandidate const & sisterJet = i->sisterJet();
      TLorentzVector p42 ( sisterJet.px(), sisterJet.py(), sisterJet.pz(), sisterJet.energy() );


      // Now check the source.
      double dR = -1;
      if ( sisterJet.masterClonePtr().isNonnull() ) {
        dR = p41.DeltaR( p42 );
      }
      // Add to the vector to be sorted later
      if ( verbose ) cout << "Adding classification: pdgId = " << pdgId << ", flavorSource = " << flavorSource << ", dR = " << dR << endl;
      classification.push_back( helpers::FlavorHistoryEventHelper ( pdgId, flavorSource, dR ) );
    } else{
      if ( verbose ) cout << "No matched jet found, not adding to classification list" << endl;
    }
  } 


  // Sort by priority
  
  // Priority is:
  // 
  //  1. flavor (5 > 4)
  //  2. type:
  //      2a. Flavor decay
  //      2b. Matrix element
  //      2c. Flavor excitation
  //      2d. Gluon splitting
  //  3. delta R (if applicable)
  if ( classification.size() > 0 ) { 


    std::sort( classification.begin(), classification.end() );

    if ( verbose ){ cout << "Writing out list of classifications" << endl;
    copy(classification.begin(), classification.end(), 
         ostream_iterator<helpers::FlavorHistoryEventHelper>(cout, ""));
    }

    helpers::FlavorHistoryEventHelper const & best = *(classification.rbegin());
    dR_ = best.dR;
    highestFlavor_ = best.flavor;
    flavorSource_ = best.flavorSource;
  }
  else {
    dR_ = -1.0;
    highestFlavor_ = 0;
    flavorSource_ = FlavorHistory::FLAVOR_NULL;
  }

  // now we're cached, can return values quickly
  cached_ = true;
}