CMSInsideOutAlgorithm.h

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#ifndef RecoJets_JetAlgorithms_CMSInsideOutAlgorithm_h
#define RecoJets_JetAlgorithms_CMSInsideOutAlgorithm_h

#include <list>
#include <algorithm>

#include "DataFormats/Candidate/interface/Candidate.h"
#include "DataFormats/Math/interface/deltaR.h"
#include <limits>
#include <vector>
#include <list>

#include "fastjet/PseudoJet.hh"

class CMSInsideOutAlgorithm {
public:
  typedef reco::Particle::LorentzVector LorentzVector;
  typedef std::list<fastjet::PseudoJet>::iterator inputListIter;
  // binary predicate to sort a std::list of std::list<InputItem> iterators by increasing deltaR
  // from a eta-phi point specified in the ctor
  class ListIteratorLesserByDeltaR {
  public:
    ListIteratorLesserByDeltaR(const double& eta, const double& phi) : seedEta_(eta), seedPhi_(phi) {}
    bool operator()(const inputListIter& A, const inputListIter& B) const {
      double deltaR2A = reco::deltaR2((*A).eta(), seedEta_, (*A).phi(), seedPhi_);
      double deltaR2B = reco::deltaR2((*B).eta(), seedEta_, (*B).phi(), seedPhi_);
      return fabs(deltaR2A - deltaR2B) > std::numeric_limits<double>::epsilon()
                 ? deltaR2A < deltaR2B
                 : reco::deltaPhi((*A).phi(), seedPhi_) < reco::deltaPhi((*B).phi(), seedPhi_);
    };

  private:
    double seedEta_, seedPhi_;
  };

  CMSInsideOutAlgorithm(double seedObjectPt, double growthParameter, double maxSize, double minSize)
      : seedThresholdPt_(seedObjectPt),
        growthParameterSquared_(growthParameter * growthParameter),
        maxSizeSquared_(maxSize * maxSize),
        minSizeSquared_(minSize * minSize) {}

  void run(const std::vector<fastjet::PseudoJet>& fInput, std::vector<fastjet::PseudoJet>& fOutput);

private:
  double seedThresholdPt_;
  double growthParameterSquared_;
  double maxSizeSquared_;
  double minSizeSquared_;
};

#endif