CMSSW Reference Manual

CMSIterativeConeAlgorithm::CMSIterativeConeAlgorithm	(	double	seed,
		double	radius
	)			`[inline]`

Constructor.

Parameters:

	seed	defines the minimum ET in GeV of a tower that can seed a jet.
	radius	defines the maximum radius of a jet in eta-phi space.

Definition at line 25 of file CMSIterativeConeAlgorithm.h.

00025                                                        : 
00026     theSeedThreshold(seed),
00027     theConeRadius(radius)
00028     { }

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

Find the ProtoJets from the collection of input Candidates.

Definition at line 20 of file CMSIterativeConeAlgorithm.cc.

References deltaR2(), eta, iggi_31X_cfg::input, iteration, phi, python::multivaluedict::sort(), theConeRadius, and theSeedThreshold.

Referenced by FWLiteJetProducer::makeIterativeConeJets(), and cms::IterativeConePilupSubtractionJetProducer::runAlgorithm().

00020                                                                                                   {
00021   if (!fOutput) return;
00022   //make a list of input objects ordered by ET
00023   list<InputItem> input;
00024   for (InputCollection::const_iterator towerIter = fInput.begin();
00025        towerIter != fInput.end(); ++towerIter) {
00026     input.push_back(*towerIter);
00027   }   
00028   GreaterByEtRef <InputItem> compCandidate;
00029   input.sort(compCandidate);
00030 
00031   //find jets
00032   while( !input.empty() && input.front()->et() > theSeedThreshold ) {
00033     //cone centre 
00034     double eta0=input.front()->eta();
00035     double phi0=input.front()->phi();
00036     //protojet properties
00037     double eta=0;
00038     double phi=0;
00039     double et=0;
00040     //list of towers in cone
00041     list< list<InputItem>::iterator> cone;
00042     for(int iteration=0;iteration<100;iteration++){
00043       cone.clear();
00044       eta=0;
00045       phi=0;
00046       et=0;
00047       for(list<InputItem>::iterator inp=input.begin();
00048           inp!=input.end();inp++){
00049         InputItem tower = *inp; 
00050         if( deltaR2(eta0,phi0,tower->eta(),tower->phi()) < 
00051             theConeRadius*theConeRadius) {
00052           cone.push_back(inp);
00053           eta+= tower->et()*tower->eta();
00054           double dphi=tower->phi()-phi0;
00055           if(dphi>M_PI) dphi-=2*M_PI;
00056           else if(dphi<=-M_PI) dphi+=2*M_PI;
00057           phi+=tower->et()*dphi;
00058           et +=tower->et();
00059         }
00060       }
00061       eta=eta/et;
00062       phi=phi0+phi/et;
00063       if(phi>M_PI)phi-=2*M_PI;
00064       else if(phi<=-M_PI)phi+=2*M_PI;
00065       
00066       if(fabs(eta-eta0)<.001 && fabs(phi-phi0)<.001) break;//stable cone found
00067       eta0=eta;
00068       phi0=phi;
00069     }
00070 
00071     //make a final jet and remove the jet constituents from the input list 
00072     InputCollection jetConstituents;     
00073     list< list<InputItem>::iterator>::const_iterator inp;
00074     for(inp=cone.begin();inp!=cone.end();inp++)  {
00075       jetConstituents.push_back(**inp);
00076       input.erase(*inp);
00077     }
00078     fOutput->push_back (ProtoJet (jetConstituents));
00079 
00080   } //loop over seeds ended
00081   GreaterByPt<ProtoJet> compJets;
00082   sort (fOutput->begin (), fOutput->end (), compJets);
00083 }

double CMSIterativeConeAlgorithm::theConeRadius [private]

Definition at line 36 of file CMSIterativeConeAlgorithm.h.

Referenced by run().

double CMSIterativeConeAlgorithm::theSeedThreshold [private]

Definition at line 35 of file CMSIterativeConeAlgorithm.h.

Referenced by run().

CMSIterativeConeAlgorithm Class Reference

Public Member Functions

Private Attributes

Detailed Description

Constructor & Destructor Documentation

Member Function Documentation

Member Data Documentation


Public Member Functions
	CMSIterativeConeAlgorithm (double seed, double radius)
	Constructor.
void	run (const JetReco::InputCollection &fInput, JetReco::OutputCollection *fOutput) const
	Find the ProtoJets from the collection of input Candidates.
Private Attributes
double	theConeRadius
double	theSeedThreshold