#include <FastJetFWLiteWrapper.h>

Public Member Functions
	FastJetFWLiteWrapper ()
double	getPtMin ()
double	getRParam ()
void	run (const JetReco::InputCollection &fInput, JetReco::OutputCollection *fOutput)
void	setPtMin (double aPtMin)
void	setRParam (double aRparam)
	~FastJetFWLiteWrapper ()
Private Attributes
fastjet::ActiveAreaSpec *	mActiveArea
fastjet::JetDefinition *	mJetDefinition
int	theActive_Area_Repeats_
double	theDcut_
bool	theDoSubtraction_
double	theGhost_EtaMax_
double	theGhostArea_
double	theMedian_Pt_Per_Area_
int	theMode_
int	theNjets_
double	thePtMin_
double	theRparam_

Detailed Description

FastJetFWLiteWrapper is the Wrapper subclass which runs the FastJetAlgorithm for jetfinding.

The FastJet package, written by Matteo Cacciari and Gavin Salam, provides a fast implementation of the longitudinally invariant kt and longitudinally invariant inclusive Cambridge/Aachen jet finders. More information can be found at: https://parthe.lpthe.jussieu.fr/~salam/fastjet/

Authors:: Andreas Oehler, University Karlsruhe (TH) and Dorian Kcira, Institut de Physique Nucleaire Departement de Physique Universite Catholique de Louvain have written the FastJetFWLiteWrapper class which uses the above mentioned package within the Framework of CMSSW

Version:: 1st Version Nov. 6 2006

Definition at line 45 of file FastJetFWLiteWrapper.h.

Constructor & Destructor Documentation

FastJetFWLiteWrapper::FastJetFWLiteWrapper ( )

Definition at line 38 of file FastJetFWLiteWrapper.cc.

References gather_cfg::cout, mActiveArea, theActive_Area_Repeats_, theDcut_, theDoSubtraction_, theGhost_EtaMax_, theGhostArea_, theMode_, theNjets_, thePtMin_, and theRparam_.

  : mJetDefinition (0), 
    mActiveArea (0)
{

  //default ktRParam should be 1
  theRparam_=1;
  //default PtMin should be 10
  thePtMin_=10.;
  //default JetFinder should be "kt_algorithm"
  string JetFinder="kt_algorithm";; 
  //default Strategy should be "Best" 
  string Strategy="Best";
  //default dcut should be -1 (off)
  theDcut_=-1.;
  //default njets should be -1 (off)
  theNjets_=-1;  
  //default UE_Subtraction should be false (off)
  theDoSubtraction_=false; 
  //default Ghost_EtaMax should be 6
  theGhost_EtaMax_=6;
  //default Active_Area_Repeats 5
  theActive_Area_Repeats_=5;
  //default GhostArea 0.01  
  theGhostArea_=0.01;
  mActiveArea = new fastjet::ActiveAreaSpec ( theGhost_EtaMax_, theActive_Area_Repeats_ , theGhostArea_);       

  
  //configuring algorithm 
  
  
  fastjet::JetFinder jet_finder;
  if (JetFinder=="cambridge_algorithm") jet_finder=fastjet::cambridge_algorithm;
  else jet_finder=fastjet::kt_algorithm;
        
  //choosing search-strategy:
        
  fastjet::Strategy strategy;
  if (Strategy=="N2Plain") strategy=fastjet::N2Plain;
  // N2Plain is best for N<50
  else if (Strategy=="N2Tiled") strategy=fastjet::N2Tiled;
  // N2Tiled is best for 50<N<400
  else if (Strategy=="N2MinHeapTiled") strategy=fastjet::N2MinHeapTiled;
  // N2MinHeapTiles is best for 400<N<15000
  else if (Strategy=="NlnN") strategy=fastjet::NlnN;
  // NlnN is best for N>15000
  else if (Strategy=="NlnNCam") strategy=fastjet::NlnNCam;
  // NlnNCam is best for N>6000
  else strategy=fastjet::Best;
  // Chooses best Strategy for every event, depending on N and ktRParam
        
  //additional strategies are possible, but not documented in the manual as they are experimental,
  //they are also not used by the "Best" method. Note: "NlnNCam" only works with 
  //the cambridge_algorithm and does not link against CGAL, "NlnN" is only 
  //available if fastjet is linked against CGAL.
  //The above given numbers of N are for ktRaram=1.0, for other ktRParam the numbers would be 
  //different.
  
  theMode_=0;
  if ((theNjets_!=-1)&&(theDcut_==-1)){
    theMode_=3;
  }
  else if ((theNjets_==-1)&&(theDcut_!=-1)){
    theMode_=2;
  }
  else if ((theNjets_!=-1)&&(theDcut_!=-1)){
    cout  <<"[FastJetWrapper] `njets` and `dcut` set!=-1! - running inclusive Mode"<<endl;
    theMode_=1;
  }
  else {
    theMode_=0;     
  }
        
  // theJetConfig_->theJetDef=fastjet::JetDefinition(jet_finder, theRparam_, strategy);
  cout <<"*******************************************"<<endl;
  cout <<"* Configuration of FastJet                "<<endl;
  if (theDoSubtraction_) cout <<"* running with ActiveAreaSubtraction(median)"<<endl;
  switch (theMode_){
  case 0:
    cout <<"* Mode     : inclusive"<<endl;
    cout <<"* PtMin    : "<<thePtMin_<<endl;
    break;
  case 1:
    cout <<"* [WARNING] Mode     : inclusive - dcut and njets set!"<<endl;
    cout <<"* PtMin    : "<<thePtMin_<<endl;
    break;
  case 2:    
    cout <<"* Mode     : exclusive"<<endl;
    cout <<"* dcut     : "<<theDcut_<<endl;
    break;
  case 3:
    cout <<"* Mode     : exclusive"<<endl;
    cout <<"* njets    : "<<theNjets_<<endl;
    break;
  }
  cout <<"* Rparam   : "<<theRparam_<<endl;
  cout <<"* JetFinder: "<<JetFinder<<endl;
  cout <<"* Strategy : "<<Strategy<<endl;
  cout <<"*******************************************"<<endl;
  
}

FastJetFWLiteWrapper::~FastJetFWLiteWrapper ( )

Definition at line 33 of file FastJetFWLiteWrapper.cc.

                                           {
  delete mJetDefinition;
  delete mActiveArea;
}

Member Function Documentation

double FastJetFWLiteWrapper::getPtMin ( ) [inline]

Definition at line 79 of file FastJetFWLiteWrapper.h.

References thePtMin_.

{return thePtMin_ ;}

double FastJetFWLiteWrapper::getRParam ( ) [inline]

Definition at line 80 of file FastJetFWLiteWrapper.h.

References theRparam_.

{return  theRparam_;}

void FastJetFWLiteWrapper::run	(	const JetReco::InputCollection &	fInput,
		JetReco::OutputCollection *	fOutput
	)

Definition at line 140 of file FastJetFWLiteWrapper.cc.

References trackerHits::c, i, collect_tpl::input, metsig::jet, analyzePatCleaning_cfg::jets, mJetDefinition, p4, and thePtMin_.

                                                                                                     {
  if (!fOutput) return;
  fOutput->clear();
  
  // convert inputs
  std::vector<fastjet::PseudoJet> fjInputs;
  fjInputs.reserve (fInput.size());
  
  JetReco::InputCollection::const_iterator input = fInput.begin();
  for (unsigned i = 0; i < fInput.size(); ++i) {
    const JetReco::InputItem& c = fInput[i];
    fjInputs.push_back (fastjet::PseudoJet (c->px(),c->py(),c->pz(),c->energy()));
    fjInputs.back().set_user_index(i);
  }
   
  // create an object that represents your choice of jet finder and 
  // the associated parameters
  // run the jet clustering with the above jet definition

  // here we need to keep both pointers, as "area" interfaces are missing in base class
  fastjet::ClusterSequenceActiveArea* clusterSequenceWithArea = 0;
  fastjet::ClusterSequenceWithArea* clusterSequence = 0;
  //  if (mActiveArea) {
  // clusterSequenceWithArea = new fastjet::ClusterSequenceActiveArea (fjInputs, *mJetDefinition, *mActiveArea);
  // clusterSequence = clusterSequenceWithArea;
  // }
  // else {
  clusterSequence = new fastjet::ClusterSequenceWithArea (fjInputs, *mJetDefinition);
  // }
  // retrieve jets for selected mode
  std::vector<fastjet::PseudoJet> jets = clusterSequence->inclusive_jets (thePtMin_);

  // get PU pt
  double median_Pt_Per_Area = clusterSequenceWithArea ? clusterSequenceWithArea->pt_per_unit_area() : 0.;

  // process found jets
  for (std::vector<fastjet::PseudoJet>::const_iterator jet=jets.begin(); jet!=jets.end();++jet) {
    // jet itself
    double px=jet->px();
    double py=jet->py();
    double pz=jet->pz();
    double E=jet->E();
    double jetArea=clusterSequence->area(*jet);
    double pu=0.;
    // PU subtraction
    if (clusterSequenceWithArea) {
      fastjet::PseudoJet pu_p4 = median_Pt_Per_Area * clusterSequenceWithArea->area_4vector(*jet);
      pu = pu_p4.E();
      if (pu_p4.perp2() >= jet->perp2() || pu_p4.E() >= jet->E()) { // if the correction is too large, set the jet to zero
        px = py = pz = E = 0.;
      } 
      else {   // otherwise do an E-scheme subtraction
        px -= pu_p4.px();
        py -= pu_p4.py();
        pz -= pu_p4.pz();
        E -= pu_p4.E();
      }
    }
    math::XYZTLorentzVector p4(px,py,pz,E);
    // constituents
    std::vector<fastjet::PseudoJet> fastjet_constituents = clusterSequence->constituents(*jet);
    JetReco::InputCollection jetConstituents; 
    jetConstituents.reserve (fastjet_constituents.size());
    for (std::vector<fastjet::PseudoJet>::const_iterator itConst=fastjet_constituents.begin();
         itConst!=fastjet_constituents.end();itConst++){
      jetConstituents.push_back(fInput[(*itConst).user_index()]);
    }
    // Build ProtoJet
    fOutput->push_back(ProtoJet(p4,jetConstituents));
    fOutput->back().setJetArea (jetArea);
    fOutput->back().setPileup (pu);
  }
  // cleanup
  if (clusterSequenceWithArea) delete clusterSequenceWithArea;
  else delete clusterSequence; // sigh... No plymorphism in fastjet
}