MuonSimClassifier.cc

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// -*- C++ -*-
//
// Package:    SimMuon/MCTruth
// Class:      MuonSimClassifier
//
/*


 CLASSIFICATION: For each RECO Muon, match to SIM particle, and then:
  - If the SIM is not a Muon, label as Punchthrough (1) except if it is an electron or positron (11)
  - If the SIM is a Muon, then look at it's provenance.
     A) the SIM muon is also a GEN muon, whose parent is NOT A HADRON AND NOT A TAU
        -> classify as "primary" (4).
     B) the SIM muon is also a GEN muon, whose parent is HEAVY FLAVOURED HADRON OR A TAU
        -> classify as "heavy flavour" (3)
     C) classify as "light flavour/decay" (2)

  In any case, if the TP is not preferentially matched back to the same RECO muon,
  label as Ghost (flip the classification)


 FLAVOUR:
  - for non-muons: 0
  - for primary muons: 13
  - for non primary muons: flavour of the mother: std::abs(pdgId) of heaviest quark, or 15 for tau

*/
//
// Original Author:  G.Petrucciani and G.Abbiendi
//         Created:  Sun Nov 16 16:14:09 CET 2008
//         revised:  3/Aug/2017
//


// system include files
#include <memory>
#include <set>

// user include files
#include "FWCore/Framework/interface/Frameworkfwd.h"
#include "FWCore/Framework/interface/stream/EDProducer.h"

#include "FWCore/Framework/interface/Event.h"
#include "FWCore/Framework/interface/MakerMacros.h"
#include "FWCore/Framework/interface/EventSetup.h"
#include "FWCore/Framework/interface/ESHandle.h"

#include "FWCore/ParameterSet/interface/ParameterSet.h"

#include "DataFormats/Common/interface/View.h"
#include "DataFormats/Common/interface/ValueMap.h"
#include "DataFormats/Common/interface/Association.h"

#include "DataFormats/MuonReco/interface/Muon.h"
#include "DataFormats/MuonReco/interface/MuonSimInfo.h"
#include "DataFormats/HepMCCandidate/interface/GenParticle.h"
#include "DataFormats/HepMCCandidate/interface/GenParticleFwd.h"

#include "SimDataFormats/Associations/interface/MuonToTrackingParticleAssociator.h"
#include "SimTracker/Records/interface/TrackAssociatorRecord.h"
#include "SimDataFormats/TrackingAnalysis/interface/TrackingVertex.h"

#include "CommonTools/Utils/interface/StringCutObjectSelector.h"

//
// class decleration
class MuonSimClassifier : public edm::stream::EDProducer<> {
    public:
        explicit MuonSimClassifier(const edm::ParameterSet&);
        ~MuonSimClassifier() override;

    private:
        void produce(edm::Event&, const edm::EventSetup&) override;
        edm::EDGetTokenT<edm::View<reco::Muon> > muonsToken_;

        reco::MuonTrackType trackType_;

        edm::EDGetTokenT<TrackingParticleCollection> trackingParticlesToken_;

        edm::InputTag associatorLabel_;
        edm::EDGetTokenT<reco::MuonToTrackingParticleAssociator> muAssocToken_;

        double decayRho_, decayAbsZ_;

        bool linkToGenParticles_;
        edm::InputTag genParticles_;
        edm::EDGetTokenT<reco::GenParticleCollection> genParticlesToken_;

        int flavour(int pdgId) const ;

        template<typename T>
        void writeValueMap(edm::Event &iEvent,
                const edm::Handle<edm::View<reco::Muon> > & handle,
                const std::vector<T> & values,
                const std::string    & label) const ;

        TrackingParticleRef getTpMother(TrackingParticleRef tp) {
            if (tp.isNonnull() && tp->parentVertex().isNonnull() && !tp->parentVertex()->sourceTracks().empty()) {
                return tp->parentVertex()->sourceTracks()[0];
            } else {
                return TrackingParticleRef();
            }
        }

        int convertAndPush(const TrackingParticle &tp,
                           reco::GenParticleCollection &out,
                           const TrackingParticleRef &momRef,
                           const edm::Handle<reco::GenParticleCollection> & genParticles) const ;
};


MuonSimClassifier::MuonSimClassifier(const edm::ParameterSet &iConfig) :
    muonsToken_(consumes<edm::View<reco::Muon> >(iConfig.getParameter<edm::InputTag>("muons"))),
    trackingParticlesToken_(consumes<TrackingParticleCollection>(iConfig.getParameter<edm::InputTag>("trackingParticles"))),
    muAssocToken_(consumes<reco::MuonToTrackingParticleAssociator>(iConfig.getParameter<edm::InputTag>("associatorLabel"))),
    decayRho_(iConfig.getParameter<double>("decayRho")),
    decayAbsZ_(iConfig.getParameter<double>("decayAbsZ")),
    linkToGenParticles_(iConfig.getParameter<bool>("linkToGenParticles")),
    genParticles_(linkToGenParticles_ ? iConfig.getParameter<edm::InputTag>("genParticles") : edm::InputTag())

{
    std::string trackType = iConfig.getParameter< std::string >("trackType");
    if (trackType == "inner") trackType_ = reco::InnerTk;
    else if (trackType == "outer") trackType_ = reco::OuterTk;
    else if (trackType == "global") trackType_ = reco::GlobalTk;
    else if (trackType == "segments") trackType_ = reco::Segments;
    else if (trackType == "glb_or_trk") trackType_ = reco::GlbOrTrk;
    else throw cms::Exception("Configuration") << "Track type '" << trackType << "' not supported.\n";
    if (linkToGenParticles_) {
      genParticlesToken_ = consumes<reco::GenParticleCollection>(genParticles_);
    }

    produces<edm::ValueMap<reco::MuonSimInfo> >();
    if (linkToGenParticles_) {
        produces<reco::GenParticleCollection>("secondaries");
        produces<edm::Association<reco::GenParticleCollection> >("toPrimaries");
        produces<edm::Association<reco::GenParticleCollection> >("toSecondaries");
    }
}

MuonSimClassifier::~MuonSimClassifier()
{
}

void dumpFormatedInfo(const reco::MuonSimInfo& simInfo){
  return;
  LogTrace("MuonSimClassifier") << 
    "\t Particle pdgId = " << simInfo.pdgId << 
    ", (Event,Bx) = "<< "(" << simInfo.tpEvent << "," << simInfo.tpBX << ")" <<
    "\n\t   q*p = " << simInfo.charge*simInfo.p4.P() << 
    ", pT = " << simInfo.p4.pt() << ", eta = " << simInfo.p4.eta() << ", phi = " << simInfo.p4.phi() <<
    "\n\t   produced at vertex rho = " << simInfo.vertex.Rho() << ", z = " << simInfo.vertex.Z() <<
    ", (GEANT4 process = " << simInfo.g4processType << ")\n";
}

void
MuonSimClassifier::produce(edm::Event& iEvent, const edm::EventSetup& iSetup)
{
    edm::Handle<edm::View<reco::Muon> > muons;
    iEvent.getByToken(muonsToken_, muons);

    edm::Handle<TrackingParticleCollection> trackingParticles;
    iEvent.getByToken(trackingParticlesToken_, trackingParticles);

    edm::Handle<reco::GenParticleCollection> genParticles;
    if (linkToGenParticles_) {
        iEvent.getByToken(genParticlesToken_, genParticles);
    }

    edm::Handle<reco::MuonToTrackingParticleAssociator> associatorBase;
    iEvent.getByToken(muAssocToken_, associatorBase);
    const reco::MuonToTrackingParticleAssociator * assoByHits = associatorBase.product();

    reco::MuonToSimCollection recSimColl;
    reco::SimToMuonCollection simRecColl;
    LogTrace("MuonSimClassifier") <<"\n ***************************************************************** ";
    LogTrace("MuonSimClassifier") <<  " RECO MUON association, type:  "<< trackType_;
    LogTrace("MuonSimClassifier") <<  " ***************************************************************** \n";

    edm::RefToBaseVector<reco::Muon> allMuons;
    for (size_t i = 0, n = muons->size(); i < n; ++i) {
      allMuons.push_back(muons->refAt(i));
    }
    
    edm::RefVector<TrackingParticleCollection> allTPs;
    for (size_t i = 0, n = trackingParticles->size(); i < n; ++i) {
        allTPs.push_back(TrackingParticleRef(trackingParticles,i));
    }

    assoByHits->associateMuons(recSimColl, simRecColl, allMuons, trackType_, allTPs);

    // for global muons without hits on muon detectors, look at the linked standalone muon
    reco::MuonToSimCollection updSTA_recSimColl;
    reco::SimToMuonCollection updSTA_simRecColl;
    if (trackType_ == reco::GlobalTk) {
      LogTrace("MuonSimClassifier") <<"\n ***************************************************************** ";
      LogTrace("MuonSimClassifier") <<  " STANDALONE (UpdAtVtx) MUON association ";
      LogTrace("MuonSimClassifier") <<  " ***************************************************************** \n";
      assoByHits->associateMuons(updSTA_recSimColl, updSTA_simRecColl, allMuons, reco::OuterTk, allTPs);
    }

    typedef reco::MuonToSimCollection::const_iterator r2s_it;
    typedef reco::SimToMuonCollection::const_iterator s2r_it;

    size_t nmu = muons->size();
    LogTrace("MuonSimClassifier") <<"\n There are "<<nmu<<" reco::Muons.";

    std::vector<reco::MuonSimInfo> simInfo;

    std::unique_ptr<reco::GenParticleCollection> secondaries;     // output collection of secondary muons
    std::map<TrackingParticleRef, int>         tpToSecondaries; // map from tp to (index+1) in output collection
    std::vector<int> muToPrimary(nmu, -1), muToSecondary(nmu, -1); // map from input into (index) in output, -1 for null
    if (linkToGenParticles_) secondaries.reset(new reco::GenParticleCollection());
    
    // loop on reco muons
    for(size_t i = 0; i < nmu; ++i) {
      simInfo.push_back(reco::MuonSimInfo());
      LogTrace("MuonSimClassifier") <<"\n reco::Muon # "<<i;

        TrackingParticleRef        tp;
        edm::RefToBase<reco::Muon> muMatchBack;
        r2s_it match = recSimColl.find(allMuons.at(i));
        s2r_it matchback;
        if (match != recSimColl.end()) {
      // match->second is vector, front is first element, first is the ref (second would be the quality)
      tp = match->second.front().first;
      simInfo[i].tpId = tp.isNonnull() ? tp.key() : -1; // we check, even if null refs should not appear here at all
      simInfo[i].tpAssoQuality = match->second.front().second;
      s2r_it matchback = simRecColl.find(tp);
      if (matchback != simRecColl.end()) {
        muMatchBack = matchback->second.front().first;
      } else {
        LogTrace("MuonSimClassifier") << "\n***WARNING:  This I do NOT understand: why no match back? *** \n";
      }
        } else {
      if ((trackType_ == reco::GlobalTk) && allMuons.at(i)->isGlobalMuon()) {
        // perform a second attempt, matching with the standalone muon
        r2s_it matchSta = updSTA_recSimColl.find(allMuons.at(i));
        if (matchSta != updSTA_recSimColl.end()) {
          tp    = matchSta->second.front().first;
          simInfo[i].tpId = tp.isNonnull() ? tp.key() : -1; // we check, even if null refs should not appear here at all
          simInfo[i].tpAssoQuality = matchSta->second.front().second;
          s2r_it matchback = updSTA_simRecColl.find(tp);
          if (matchback != updSTA_simRecColl.end()) {
        muMatchBack = matchback->second.front().first;
          } else {
        LogTrace("MuonSimClassifier") << 
          "\n***WARNING:  This I do NOT understand: why no match back in updSTA? *** \n";
          }
        }
      } else {
        LogTrace("MuonSimClassifier") <<"\t No matching TrackingParticle is found ";
      }
    }
    
        if (tp.isNonnull()) {
      bool isGhost = muMatchBack != allMuons.at(i);
      if (isGhost) LogTrace("MuonSimClassifier") <<"\t *** This seems a Duplicate muon ! classif[i] will be < 0 ***";

      // identify signal and pileup TP
      simInfo[i].tpBX      = tp->eventId().bunchCrossing();
      simInfo[i].tpEvent   = tp->eventId().event();

      simInfo[i].pdgId = tp->pdgId();
      simInfo[i].vertex = tp->vertex();

      // added info on GEANT process producing the TrackingParticle
      const std::vector<SimVertex> & g4Vs = tp->parentVertex()->g4Vertices();
      simInfo[i].g4processType = g4Vs[0].processType();
      
      simInfo[i].charge = tp->charge();
      simInfo[i].p4 = tp->p4();

      // Try to extract mother and grand mother of this muon.
      // Unfortunately, SIM and GEN histories require diffent code :-(
      if (!tp->genParticles().empty()) { // Muon is in GEN
        reco::GenParticleRef genp   = tp->genParticles()[0];
        reco::GenParticleRef genMom = genp->numberOfMothers() > 0 ? genp->motherRef() : reco::GenParticleRef();
        reco::GenParticleRef mMom = genMom;
          
        if (genMom.isNonnull()) {
          if (genMom->pdgId() != tp->pdgId()) {
        simInfo[i].motherPdgId  = genMom->pdgId();
        simInfo[i].motherStatus = genMom->status();
        simInfo[i].motherVertex = genMom->vertex(); 
          } else {
        // if mother has the same identity look backwards for the real mother (it may happen in radiative decays) 
        int jm = 0;
        while (mMom->pdgId() == tp->pdgId()) {
          jm++;
          if (mMom->numberOfMothers() > 0) {
            mMom = mMom->motherRef();
          }
          LogTrace("MuonSimClassifier") 
            << "\t\t backtracking mother "<<jm<<", pdgId = "<<mMom->pdgId()<<", status= " <<mMom->status();
        }
        genMom = mMom; // redefine genMom
        simInfo[i].motherPdgId  = genMom->pdgId();
        simInfo[i].motherStatus = genMom->status();
        simInfo[i].motherVertex = genMom->vertex(); 
          }
          dumpFormatedInfo(simInfo[i]);
          LogTrace("MuonSimClassifier") << 
        "\t   has GEN mother pdgId = " << simInfo[i].motherPdgId << 
        " (status = " << simInfo[i].motherStatus << ")";
        
          reco::GenParticleRef genGMom = genMom->numberOfMothers() > 0 ? genMom->motherRef() : reco::GenParticleRef();
          
          if (genGMom.isNonnull()) {
        simInfo[i].grandMotherPdgId = genGMom->pdgId();
        LogTrace("MuonSimClassifier") << 
          "\t\t mother prod. vertex rho = " << simInfo[i].motherVertex.Rho() << ", z = " << simInfo[i].motherVertex.Z() << 
          ", grand-mom pdgId = " << simInfo[i].grandMotherPdgId;
          }
          // in this case, we might want to know the heaviest mom flavour
          for (reco::GenParticleRef nMom = genMom;
           nMom.isNonnull() && std::abs(nMom->pdgId()) >= 100; // stop when we're no longer looking at hadrons or mesons
           nMom = nMom->numberOfMothers() > 0 ? nMom->motherRef() : reco::GenParticleRef()) {
        int flav = flavour(nMom->pdgId());
        if (simInfo[i].heaviestMotherFlavour < flav) simInfo[i].heaviestMotherFlavour = flav;
        LogTrace("MuonSimClassifier") 
          << "\t\t backtracking flavour: mom pdgId = " << nMom->pdgId()
          << ", flavour = " << flav << ", heaviest so far = " << simInfo[i].heaviestMotherFlavour;
          }
        } else {   // mother is null ??
          dumpFormatedInfo(simInfo[i]);
          LogTrace("MuonSimClassifier") <<"\t   has NO mother!";
        }
      } else { // Muon is in SIM Only
        TrackingParticleRef simMom = getTpMother(tp);
        if (simMom.isNonnull()) {
          simInfo[i].motherPdgId = simMom->pdgId();
          simInfo[i].motherVertex = simMom->vertex();
          dumpFormatedInfo(simInfo[i]);
          LogTrace("MuonSimClassifier") <<
        "\t   has SIM mother pdgId = " << simInfo[i].motherPdgId << 
        " produced at rho = " << simMom->vertex().Rho() << ", z = " << simMom->vertex().Z();
          
          if (!simMom->genParticles().empty()) {
        simInfo[i].motherStatus = simMom->genParticles()[0]->status();
        reco::GenParticleRef genGMom = (simMom->genParticles()[0]->numberOfMothers() > 0 ? 
                        simMom->genParticles()[0]->motherRef() : 
                        reco::GenParticleRef());
        if (genGMom.isNonnull()) simInfo[i].grandMotherPdgId = genGMom->pdgId();
        LogTrace("MuonSimClassifier") << 
          "\t\t SIM mother is in GEN (status " << simInfo[i].motherStatus << 
          "), grand-mom id = " << simInfo[i].grandMotherPdgId;
          } else {
        simInfo[i].motherStatus = -1;
        TrackingParticleRef simGMom = getTpMother(simMom);
        if (simGMom.isNonnull()) simInfo[i].grandMotherPdgId = simGMom->pdgId();
        LogTrace("MuonSimClassifier") << 
          "\t\t SIM mother is in SIM only, grand-mom id = " << simInfo[i].grandMotherPdgId;
          }
        } else {
          dumpFormatedInfo(simInfo[i]);
          LogTrace("MuonSimClassifier") <<"\t   has NO mother!";
        }
      }
      simInfo[i].motherFlavour = flavour(simInfo[i].motherPdgId);
      simInfo[i].grandMotherFlavour = flavour(simInfo[i].grandMotherPdgId);

      // Check first IF this is a muon at all
      if (std::abs(tp->pdgId()) != 13) {
        if (std::abs(tp->pdgId()) == 11) {
          simInfo[i].primaryClass  = isGhost ? reco::MuonSimType::GhostElectron : reco::MuonSimType::MatchedElectron;
          simInfo[i].extendedClass = isGhost ? reco::ExtendedMuonSimType::ExtGhostElectron : reco::ExtendedMuonSimType::ExtMatchedElectron;
          LogTrace("MuonSimClassifier") <<"\t This is electron/positron. classif[i] = " << simInfo[i].primaryClass;
        } else {
          simInfo[i].primaryClass  = isGhost ? reco::MuonSimType::GhostPunchthrough : reco::MuonSimType::MatchedPunchthrough;
          simInfo[i].extendedClass = isGhost ? reco::ExtendedMuonSimType::ExtGhostPunchthrough : reco::ExtendedMuonSimType::ExtMatchedPunchthrough;
          LogTrace("MuonSimClassifier") <<"\t This is not a muon. Sorry. classif[i] = " << simInfo[i].primaryClass;
        }
        continue;
      }

      // Is this SIM muon also a GEN muon, with a mother?
      if (!tp->genParticles().empty() && (simInfo[i].motherPdgId != 0)) {
        if (std::abs(simInfo[i].motherPdgId) < 100 && (std::abs(simInfo[i].motherPdgId) != 15)) {
          simInfo[i].primaryClass = isGhost ? 
        reco::MuonSimType::GhostPrimaryMuon : 
        reco::MuonSimType::MatchedPrimaryMuon;
          simInfo[i].flavour = 13;
          simInfo[i].extendedClass  = isGhost ?
        reco::ExtendedMuonSimType::GhostMuonFromGaugeOrHiggsBoson :
        reco::ExtendedMuonSimType::MatchedMuonFromGaugeOrHiggsBoson;
          LogTrace("MuonSimClassifier") <<"\t This seems PRIMARY MUON ! classif[i] = " << simInfo[i].primaryClass;
        } else if (simInfo[i].motherFlavour == 4 || simInfo[i].motherFlavour == 5 || simInfo[i].motherFlavour == 15) {
          simInfo[i].primaryClass = isGhost ? 
        reco::MuonSimType::GhostMuonFromHeavyFlavour : 
        reco::MuonSimType::MatchedMuonFromHeavyFlavour;
          simInfo[i].flavour    = simInfo[i].motherFlavour;
          if (simInfo[i].motherFlavour == 15)      
        simInfo[i].extendedClass = isGhost ? 
          reco::ExtendedMuonSimType::GhostMuonFromTau :
          reco::ExtendedMuonSimType::MatchedMuonFromTau;
          else if (simInfo[i].motherFlavour == 5)  
        simInfo[i].extendedClass = isGhost ? 
          reco::ExtendedMuonSimType::GhostMuonFromB :
          reco::ExtendedMuonSimType::MatchedMuonFromB;
          else if (simInfo[i].heaviestMotherFlavour == 5) 
        simInfo[i].extendedClass = isGhost ? 
          reco::ExtendedMuonSimType::GhostMuonFromBtoC :
          reco::ExtendedMuonSimType::MatchedMuonFromBtoC;
          else 
        simInfo[i].extendedClass = isGhost ? 
          reco::ExtendedMuonSimType::GhostMuonFromC :
          reco::ExtendedMuonSimType::MatchedMuonFromC;
          LogTrace("MuonSimClassifier") <<"\t This seems HEAVY FLAVOUR ! classif[i] = " << simInfo[i].primaryClass;
        } else {
          simInfo[i].primaryClass = isGhost ? 
        reco::MuonSimType::GhostMuonFromLightFlavour : 
        reco::MuonSimType::MatchedMuonFromLightFlavour;
          simInfo[i].flavour    = simInfo[i].motherFlavour;
          LogTrace("MuonSimClassifier") <<"\t This seems LIGHT FLAVOUR ! classif[i] = " << simInfo[i].primaryClass;
        }
      } else {
        simInfo[i].primaryClass = isGhost ? 
          reco::MuonSimType::GhostMuonFromLightFlavour : 
          reco::MuonSimType::MatchedMuonFromLightFlavour;
        simInfo[i].flavour    = simInfo[i].motherFlavour;
        LogTrace("MuonSimClassifier") <<"\t This seems LIGHT FLAVOUR ! classif[i] = " << simInfo[i].primaryClass;
      }
      
      // extended classification
      // don't we override previous decisions?
      if (simInfo[i].motherPdgId == 0)
        // if it has no mom, it's not a primary particle so it won't be in ppMuX 
        simInfo[i].extendedClass = isGhost ? 
          reco::ExtendedMuonSimType::GhostMuonFromNonPrimaryParticle : 
          reco::ExtendedMuonSimType::MatchedMuonFromNonPrimaryParticle; 
      else if (std::abs(simInfo[i].motherPdgId) < 100) {
        if (simInfo[i].motherFlavour == 15)
        simInfo[i].extendedClass = isGhost ? 
          reco::ExtendedMuonSimType::GhostMuonFromTau :
          reco::ExtendedMuonSimType::MatchedMuonFromTau;
        else
          simInfo[i].extendedClass  = isGhost ?
        reco::ExtendedMuonSimType::GhostMuonFromGaugeOrHiggsBoson :
        reco::ExtendedMuonSimType::MatchedMuonFromGaugeOrHiggsBoson;
      }
      else if (simInfo[i].motherFlavour == 5) 
        simInfo[i].extendedClass = isGhost ? 
          reco::ExtendedMuonSimType::GhostMuonFromB :
          reco::ExtendedMuonSimType::MatchedMuonFromB;
      else if (simInfo[i].motherFlavour == 4) 
        {
          if (simInfo[i].heaviestMotherFlavour == 5) 
        simInfo[i].extendedClass = isGhost ? 
          reco::ExtendedMuonSimType::GhostMuonFromBtoC :
          reco::ExtendedMuonSimType::MatchedMuonFromBtoC;
          else 
        simInfo[i].extendedClass = isGhost ? 
          reco::ExtendedMuonSimType::GhostMuonFromC :
          reco::ExtendedMuonSimType::MatchedMuonFromC;
        }
      else if (simInfo[i].motherStatus != -1) { // primary light particle
        int id = std::abs(simInfo[i].motherPdgId);
        if (id != /*pi+*/211 && id != /*K+*/321 && id != 130 /*K0L*/)  
          // other light particle, possibly short-lived
          simInfo[i].extendedClass = isGhost ? 
        reco::ExtendedMuonSimType::GhostMuonFromOtherLight :
        reco::ExtendedMuonSimType::MatchedMuonFromOtherLight;
        else if (simInfo[i].vertex.Rho() < decayRho_ && std::abs(simInfo[i].vertex.Z()) < decayAbsZ_) 
          // decay a la ppMuX (primary pi/K within a cylinder)
          simInfo[i].extendedClass = isGhost ? 
        reco::ExtendedMuonSimType::GhostMuonFromPiKppMuX :
        reco::ExtendedMuonSimType::MatchedMuonFromPiKppMuX;
        else                                                           
          // late decay that wouldn't be in ppMuX
          simInfo[i].extendedClass = isGhost ? 
        reco::ExtendedMuonSimType::GhostMuonFromPiKNotppMuX :
        reco::ExtendedMuonSimType::MatchedMuonFromPiKNotppMuX;
      } else 
        // decay of non-primary particle, would not be in ppMuX
        simInfo[i].extendedClass = isGhost ? 
        reco::ExtendedMuonSimType::GhostMuonFromNonPrimaryParticle :
        reco::ExtendedMuonSimType::MatchedMuonFromNonPrimaryParticle;

      if (linkToGenParticles_ && std::abs(simInfo[i].extendedClass) >= 2) {
        // Link to the genParticle if possible, but not decays in flight (in ppMuX they're in GEN block, but they have wrong parameters)
        if (!tp->genParticles().empty() && std::abs(simInfo[i].extendedClass) >= 5) {
          if (genParticles.id() != tp->genParticles().id()) {
        throw cms::Exception("Configuration") << "Product ID mismatch between the genParticle collection (" << 
          genParticles_ << ", id " << genParticles.id() << ") and the references in the TrackingParticles (id " << 
          tp->genParticles().id() << ")\n";
          }
          muToPrimary[i] = tp->genParticles()[0].key();
        } else {
          // Don't put the same trackingParticle twice!
          int &indexPlus1 = tpToSecondaries[tp]; // will create a 0 if the tp is not in the list already
          if (indexPlus1 == 0) indexPlus1 = convertAndPush(*tp, *secondaries, getTpMother(tp), genParticles) + 1;
          muToSecondary[i] = indexPlus1 - 1;
        }
      }
      LogTrace("MuonSimClassifier") <<"\t Extended classification code = " << simInfo[i].extendedClass;
    } else { // if (tp.isNonnull())
      simInfo[i].primaryClass  = reco::MuonSimType::NotMatched;
      simInfo[i].extendedClass = reco::ExtendedMuonSimType::ExtNotMatched;
    }
    } // end loop on reco muons 

    writeValueMap(iEvent, muons, simInfo,   "");

    if (linkToGenParticles_) {
        edm::OrphanHandle<reco::GenParticleCollection> secHandle = iEvent.put(std::move(secondaries), "secondaries");
        edm::RefProd<reco::GenParticleCollection> priRP(genParticles);
        edm::RefProd<reco::GenParticleCollection> secRP(secHandle);
        std::unique_ptr<edm::Association<reco::GenParticleCollection> > outPri(new edm::Association<reco::GenParticleCollection>(priRP));
        std::unique_ptr<edm::Association<reco::GenParticleCollection> > outSec(new edm::Association<reco::GenParticleCollection>(secRP));
        edm::Association<reco::GenParticleCollection>::Filler fillPri(*outPri), fillSec(*outSec);
        fillPri.insert(muons, muToPrimary.begin(),   muToPrimary.end());
        fillSec.insert(muons, muToSecondary.begin(), muToSecondary.end());
        fillPri.fill(); fillSec.fill();
        iEvent.put(std::move(outPri), "toPrimaries");
        iEvent.put(std::move(outSec), "toSecondaries");
    }

}

template<typename T>
void
MuonSimClassifier::writeValueMap(edm::Event &iEvent,
    const edm::Handle<edm::View<reco::Muon> > & handle,
        const std::vector<T> & values,
        const std::string    & label) const
{
    using namespace edm;
    using namespace std;
    unique_ptr<ValueMap<T> > valMap(new ValueMap<T>());
    typename edm::ValueMap<T>::Filler filler(*valMap);
    filler.insert(handle, values.begin(), values.end());
    filler.fill();
    iEvent.put(std::move(valMap), label);
}

int
MuonSimClassifier::flavour(int pdgId) const {
    int flav = std::abs(pdgId);
    // for quarks, leptons and bosons except gluons, take their pdgId
    // muons and taus have themselves as flavour
    if (flav <= 37 && flav != 21) return flav;
    // look for barions
    int bflav = ((flav / 1000) % 10);
    if (bflav != 0) return bflav;
    // look for mesons
    int mflav = ((flav / 100) % 10);
    if (mflav != 0) return mflav;
    return 0;
}

// push secondary in collection.
// if it has a primary mother link to it.
int MuonSimClassifier::convertAndPush(const TrackingParticle &tp,
                                     reco::GenParticleCollection &out,
                                     const TrackingParticleRef & simMom,
                                     const edm::Handle<reco::GenParticleCollection> & genParticles) const {
    out.push_back(reco::GenParticle(tp.charge(), tp.p4(), tp.vertex(), tp.pdgId(), tp.status(), true));
    if (simMom.isNonnull() && !simMom->genParticles().empty()) {
         if (genParticles.id() != simMom->genParticles().id()) {
            throw cms::Exception("Configuration") << "Product ID mismatch between the genParticle collection (" << genParticles_ << ", id " << genParticles.id() << ") and the references in the TrackingParticles (id " << simMom->genParticles().id() << ")\n";
         }
         out.back().addMother(simMom->genParticles()[0]);
    }
    return out.size()-1;
}

//define this as a plug-in
DEFINE_FWK_MODULE(MuonSimClassifier);