MatchJet.cc

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#include <functional>
#include <algorithm>
#include <vector>
#include <memory>
#include <string>

#include <Math/GenVector/Cartesian3D.h>
#include <Math/GenVector/VectorUtil.h>

#include "DQMOffline/RecoB/interface/MatchJet.h"

#include "Matching.h"

using namespace btag;

namespace {
    inline double sqr(double val) { return val * val; }
}

MatchJet::MatchJet(const edm::ParameterSet& pSet) :
  maxChi2(pSet.getParameter<double>("maxChi2")),
  sigmaDeltaR2(sqr(pSet.getParameter<double>("sigmaDeltaR"))),
  sigmaDeltaE2(sqr(pSet.getParameter<double>("sigmaDeltaE"))),
  threshold(1.0)
{
}

void MatchJet::matchCollections(
            const edm::RefToBaseVector<reco::Jet> & refJets_,
            const edm::RefToBaseVector<reco::Jet> & recJets_,
            const reco::JetCorrector *corrector
            )
{
        refJetCorrector.setCorrector(corrector);
        recJetCorrector.setCorrector(corrector);
    
        typedef ROOT::Math::Cartesian3D<double> Vector;

    std::vector<Vector> corrRefJets;
    refJets.clear();
    for(edm::RefToBaseVector<reco::Jet>::const_iterator iter = refJets.begin();
            iter != refJets_.end(); ++iter) {
        edm::RefToBase<reco::Jet> jetRef = *iter;
        reco::Jet jet = refJetCorrector(*jetRef);
        if (jet.energy() < threshold)
            continue;

        corrRefJets.push_back(Vector(jet.px(), jet.py(), jet.pz()));
        refJets.push_back(jetRef);
    }

    std::vector<Vector> corrRecJets;
    recJets.clear();
    for(edm::RefToBaseVector<reco::Jet>::const_iterator iter = recJets.begin();
            iter != recJets_.end(); ++iter) {
        edm::RefToBase<reco::Jet> jetRec = *iter;
        reco::Jet jet = recJetCorrector(*jetRec);
        if (jet.energy() < threshold)
            continue;

        corrRecJets.push_back(Vector(jet.px(), jet.py(), jet.pz()));
        recJets.push_back(jetRec);
    }

    refToRec.clear();
    refToRec.resize(refJets.size(), -1);

    recToRef.clear();
    recToRef.resize(recJets.size(), -1);

    Matching<double> matching(corrRefJets, corrRecJets,
        [this](auto& v1, auto& v2)
        {
            double x = ROOT::Math::VectorUtil::DeltaR2(v1, v2) / this->sigmaDeltaR2 +
                       sqr(2. * (v1.R() - v2.R()) / (v1.R() + v2.R())) / this->sigmaDeltaE2;
            // Possible debug output
            // std::cout << "xxx " << ROOT::Math::VectorUtil::DeltaPhi(v1, v2) << " " << (v1.Eta() - v2.Eta())
            // << " " << (v1.R() - v2.R()) / (v1.R() + v2.R()) << " " << x << std::endl;
            return x;
        });

    typedef Matching<double>::Match Match;

    const std::vector<Match>& matches =
        matching.match(std::less<double>(),
                       [&](auto &c){ return c < this->maxChi2;});
    for(std::vector<Match>::const_iterator iter = matches.begin();
        iter != matches.end(); ++iter) {
        refToRec[iter->index1] = iter->index2;
        recToRef[iter->index2] = iter->index1;
    }
}

edm::RefToBase<reco::Jet>
MatchJet::operator() (const edm::RefToBase<reco::Jet> & recJet) const
{
    edm::RefToBase<reco::Jet> result;
    if (recJet.id() != recJets.id())
        return result;

    for(unsigned int i = 0; i != recJets.size(); ++i) {
        if (recJets[i] == recJet) {
            int match = recToRef[i];
            if (match >= 0)
                result = refJets[match];
            break;
        }
    }

    return result;
}