DimuonMCMatcher.cc

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#include "FWCore/Framework/interface/EDProducer.h"
#include "FWCore/Utilities/interface/InputTag.h"
#include "DataFormats/Candidate/interface/Candidate.h"
#include "DataFormats/Candidate/interface/CandidateFwd.h"
#include <iostream>
 
class DimuonMCMatcher : public edm::EDProducer {
public:
  DimuonMCMatcher(const edm::ParameterSet& cfg);
  void produce(edm::Event&, const edm::EventSetup&) override;
 
private:
  edm::EDGetTokenT<reco::CandidateView> srcToken_;
};
 
#include "DataFormats/HepMCCandidate/interface/GenParticle.h"
#include "DataFormats/HepMCCandidate/interface/GenParticleFwd.h"
#include "FWCore/Framework/interface/Event.h"
#include "DataFormats/Common/interface/Handle.h"
#include "FWCore/ParameterSet/interface/ParameterSet.h"
#include "DataFormats/PatCandidates/interface/Muon.h"
#include "DataFormats/PatCandidates/interface/GenericParticle.h"
using namespace std;
using namespace reco;
using namespace edm;
 
DimuonMCMatcher::DimuonMCMatcher(const edm::ParameterSet& cfg)
    : srcToken_(consumes<CandidateView>(cfg.getParameter<InputTag>("src"))) {
  produces<vector<GenParticleRef> >();
}
 
void DimuonMCMatcher::produce(edm::Event& evt, const edm::EventSetup&) {
  Handle<CandidateView> src;
  evt.getByToken(srcToken_, src);
  unique_ptr<vector<GenParticleRef> > matched(new vector<GenParticleRef>);
  matched->reserve(src->size());
  int j = 0;
  for (CandidateView::const_iterator i = src->begin(); i != src->end(); ++i) {
    j++;
    const Candidate* dau1 = i->daughter(0);
    const Candidate* dau2 = i->daughter(1);
    if (dau1 == nullptr || dau2 == nullptr)
      throw Exception(errors::InvalidReference) << "one of the two daughter does not exist\n";
    const Candidate* c1 = dau1->masterClone().get();
    GenParticleRef mc1;
    const pat::Muon* mu1 = dynamic_cast<const pat::Muon*>(c1);
    if (mu1 != nullptr) {
      mc1 = mu1->genParticleRef();
      //     if (mc1.isNonnull()) cout << "DimuonMCMatcher> genParticleRef1 " << mc1->pdgId() << endl;
    } else {
      const pat::GenericParticle* gp1 = dynamic_cast<const pat::GenericParticle*>(c1);
      if (gp1 == nullptr)
        throw Exception(errors::InvalidReference)
            << "first of two daughter is neither a pat::Muon not pat::GenericParticle\n";
      mc1 = gp1->genParticleRef();
    }
    const Candidate* c2 = dau2->masterClone().get();
    GenParticleRef mc2;
    const pat::Muon* mu2 = dynamic_cast<const pat::Muon*>(c2);
    if (mu2 != nullptr) {
      mc2 = mu2->genParticleRef();
      //      if (mc2.isNonnull()) cout << "DimuonMCMatcher> genParticleRef2 " << mc2->pdgId() << endl;
    } else {
      const pat::GenericParticle* gp2 = dynamic_cast<const pat::GenericParticle*>(c2);
      if (gp2 == nullptr)
        throw Exception(errors::InvalidReference)
            << "first of two daughter is neither a pat::Muon not pat::GenericParticle\n";
      mc2 = gp2->genParticleRef();
    }
    GenParticleRef dimuonMatch;
    //    cout << "DimuonMatcher>  mc1 " << mc1.isNonnull() << "   mc2 " << mc2.isNonnull() << endl;
    if (mc1.isNonnull() && mc2.isNonnull()) {
      int k = 0;
      do {
        k++;
        mc1 = mc1->numberOfMothers() > 0 ? mc1->motherRef() : GenParticleRef();
        mc2 = mc2->numberOfMothers() > 0 ? mc2->motherRef() : GenParticleRef();
        //  cout << "DimuonMCMatcher> do loop: " << k << "  id1 " << mc1->pdgId() << "    id2 " << mc2->pdgId() << endl;
      } while (mc1 != mc2 && mc1.isNonnull() && mc2.isNonnull());
      if (mc1.isNonnull() && mc2.isNonnull() && mc1->pdgId() == 23) {
        dimuonMatch = mc1;
      }
    }
    //    cout << "DimuonMatcher> dimuonMatch " << dimuonMatch.isNonnull() << endl;
    matched->push_back(dimuonMatch);
  }
 
  evt.put(std::move(matched));
}
 
#include "FWCore/Framework/interface/MakerMacros.h"
 
DEFINE_FWK_MODULE(DimuonMCMatcher);