fastjet::CMSIterativeConePlugin Class Reference

CMSIterativeConePlugin is a plugin for fastjet (v2.4 upwards). More...

#include <CMSIterativeConePlugin.hh>

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List of all members.

Public Member Functions

 CMSIterativeConePlugin (double ConeRadius, double SeedThreshold=1.0)
 Main constructor for the CMSIterativeCone Plugin class.
 CMSIterativeConePlugin (const CMSIterativeConePlugin &plugin)
 copy constructor
virtual std::string description () const
 return a textual description of the jet-definition implemented in this plugin
virtual void run_clustering (ClusterSequence &) const
 given a ClusterSequence that has been filled up with initial particles, the following function should fill up the rest of the ClusterSequence, using the following member functions of ClusterSequence:

  • plugin_do_ij_recombination(.

virtual double R () const
 the plugin mechanism's standard way of accessing the jet radius here we return the R of the last alg in the list
virtual double seed_threshold () const
 get the seed threshold

Private Attributes

double theConeRadius
 cone radius
double theSeedThreshold
 seed threshold

Detailed Description

CMSIterativeConePlugin is a plugin for fastjet (v2.4 upwards).

Definition at line 47 of file CMSIterativeConePlugin.hh.

Constructor & Destructor Documentation

fastjet::CMSIterativeConePlugin::CMSIterativeConePlugin ( double  ConeRadius,
double  SeedThreshold = 1.0 
) [inline]

Main constructor for the CMSIterativeCone Plugin class.

The arguments are ConeRadius the radius of the cone SeedThreshold a threshold for the seeds to iterate from

NOTE: to be more coherent with all other fastjet plugins, we've put the radius before the seed threshold. CMS does the opposite. In this way, we also put a default value of 0 for the seed threshold.

Definition at line 60 of file CMSIterativeConePlugin.hh.

00060                                                                        :
00061     theConeRadius(ConeRadius), theSeedThreshold(SeedThreshold){}

fastjet::CMSIterativeConePlugin::CMSIterativeConePlugin ( const CMSIterativeConePlugin &  plugin  )  [inline]

copy constructor

Definition at line 64 of file CMSIterativeConePlugin.hh.

00064                                                                  {
00065     *this = plugin;
00066   }

Member Function Documentation

string fastjet::CMSIterativeConePlugin::description (  )  const [virtual]

return a textual description of the jet-definition implemented in this plugin

Implements JetDefinition::Plugin.

Definition at line 68 of file CMSIterativeConePlugin.cc.

References theConeRadius, and theSeedThreshold.

00068                                                   {
00069   ostringstream desc;
00070   desc << "CMSIterativeCone plugin with R = " << theConeRadius << " and seed threshold = " << theSeedThreshold;
00071   return desc.str();
00072 }

virtual double fastjet::CMSIterativeConePlugin::R (  )  const [inline, virtual]

the plugin mechanism's standard way of accessing the jet radius here we return the R of the last alg in the list

Implements JetDefinition::Plugin.

Definition at line 74 of file CMSIterativeConePlugin.hh.

00074 {return theConeRadius;}

void fastjet::CMSIterativeConePlugin::run_clustering ( ClusterSequence &   )  const [virtual]

given a ClusterSequence that has been filled up with initial particles, the following function should fill up the rest of the ClusterSequence, using the following member functions of ClusterSequence:

  • plugin_do_ij_recombination(.

..)

  • plugin_do_iB_recombination(...)

Implements JetDefinition::Plugin.

Definition at line 74 of file CMSIterativeConePlugin.cc.

References fastjet::deltaR2(), PseudoJet::Et(), PseudoJet::eta(), ClusterSequence::jets(), M_PI, PseudoJet::phi(), fastjet::d0::inline_maths::phi(), ClusterSequence::plugin_record_iB_recombination(), ClusterSequence::plugin_record_ij_recombination(), theConeRadius, and theSeedThreshold.

00074                                                                              {
00075 
00076   // This code is adapted from CMSIterativeConeAlgorithms.cc from the
00077   // CMSSW software. 
00078   // The adaptation is just meant to use 
00079   //   - the FastJet 4-vectors instead of the CMS ones
00080   //   - the FastJet clustering history structures instead of the 
00081   //     ProtoJet one used by CMS.
00082 
00083   //make a list of input objects ordered by ET
00084   //cout << "copying the list of particles" << endl;
00085   list<PseudoJet> input;
00086   for (unsigned int i=0 ; i<clust_seq.jets().size() ; i++) {
00087     input.push_back(clust_seq.jets()[i]);
00088   }
00089   NumericSafeGreaterByEt<PseudoJet> compCandidate;
00090   //cout << "sorting" << endl;
00091   input.sort(compCandidate);
00092 
00093   //find jets
00094   //cout << "launching the main loop" << endl;
00095   while( !input.empty() && (input.front().Et() > theSeedThreshold )) {
00096     //cone centre 
00097     double eta0=input.front().eta();
00098     double phi0=input.front().phi();
00099     //protojet properties
00100     double eta=0;
00101     double phi=0;
00102     double et=0;
00103     //list of towers in cone
00104     list< list<PseudoJet>::iterator> cone;
00105     for(int iteration=0;iteration<100;iteration++){
00106       //cout << "iterating" << endl;
00107       cone.clear();
00108       eta=0;
00109       phi=0;
00110       et=0;
00111       for(list<PseudoJet>::iterator inp=input.begin();
00112           inp!=input.end();inp++){
00113         const PseudoJet tower = *inp;   
00114         if( deltaR2(eta0,phi0,tower.eta(),tower.phi()) < 
00115             theConeRadius*theConeRadius) {
00116           double tower_et = tower.Et();   
00117           cone.push_back(inp);
00118           eta+= tower_et*tower.eta();
00119           double dphi=tower.phi()-phi0;
00120           if(dphi>M_PI) dphi-=2*M_PI;
00121           else if(dphi<=-M_PI) dphi+=2*M_PI;
00122           phi+=tower_et*dphi;
00123           et +=tower_et;
00124         }
00125       }
00126       eta=eta/et;
00127       phi=phi0+phi/et;
00128       if(phi>M_PI)phi-=2*M_PI;
00129       else if(phi<=-M_PI)phi+=2*M_PI;
00130       
00131       if(fabs(eta-eta0)<.001 && fabs(phi-phi0)<.001) break;//stable cone found
00132       eta0=eta;
00133       phi0=phi;
00134     }
00135 
00136     //cout << "make the jet final" << endl;
00137 
00138     //make a final jet and remove the jet constituents from the input list 
00139     //  InputCollection jetConstituents;     
00140     //  list< list<InputItem>::iterator>::const_iterator inp;
00141     //  for(inp=cone.begin();inp!=cone.end();inp++)  {
00142     //    jetConstituents.push_back(**inp);
00143     //    input.erase(*inp);
00144     //  }
00145     //  fOutput->push_back (ProtoJet (jetConstituents));
00146     //
00147     // IMPORTANT NOTE:
00148     //   while the stability of the stable cone is tested using the Et
00149     //   scheme recombination, the final jet uses E-scheme
00150     //   recombination.
00151     //
00152     // The technique used here is the same as what we already used for
00153     // SISCone except that we act on the 'cone' list.
00154     // We successively merge the particles that make up the cone jet
00155     // until we have all particles in it.  We start off with the zeroth
00156     // particle.
00157     list< list<PseudoJet>::iterator>::const_iterator inp;
00158     inp = cone.begin();
00159     int jet_k = (*inp)->cluster_hist_index();
00160     // gps tmp
00161     //float px=(*inp)->px(), py=(*inp)->py(), pz=(*inp)->pz(), E = (*inp)->E();
00162 
00163     // remove the particle from the list and jump to the next one
00164     input.erase(*inp);
00165     inp++;
00166 
00167     // now loop over the remaining particles
00168     while (inp != cone.end()){
00169       // take the last result of the merge
00170       int jet_i = jet_k;
00171       // and the next element of the jet
00172       int jet_j = (*inp)->cluster_hist_index();
00173       // and merge them (with a fake dij)
00174       double dij = 0.0;
00175 
00176       // create the new jet by hand so that we can adjust its user index
00177       // Note again the use of the E-scheme recombination here!
00178       PseudoJet newjet = clust_seq.jets()[jet_i] + clust_seq.jets()[jet_j];
00179 
00180       // gps tmp to try out floating issues
00181       //px+=(*inp)->px(), py+=(*inp)->py(), pz+=(*inp)->pz(), E += (*inp)->E();
00182       //PseudoJet newjet(px,py,pz,E);
00183         
00184       clust_seq.plugin_record_ij_recombination(jet_i, jet_j, dij, newjet, jet_k);
00185 
00186       // remove the particle from the list and jump to the next one
00187       input.erase(*inp);
00188       inp++;
00189     }
00190 
00191     // we have merged all the jet's particles into a single object, so now
00192     // "declare" it to be a beam (inclusive) jet.
00193     // [NB: put a sensible looking d_iB just to be nice...]
00194     double d_iB = clust_seq.jets()[jet_k].perp2();
00195     clust_seq.plugin_record_iB_recombination(jet_k, d_iB);
00196 
00197 
00198   } //loop over seeds ended
00199 
00200     
00201 }

virtual double fastjet::CMSIterativeConePlugin::seed_threshold (  )  const [inline, virtual]

get the seed threshold

Definition at line 77 of file CMSIterativeConePlugin.hh.

00077 {return theSeedThreshold;}

Member Data Documentation

double fastjet::CMSIterativeConePlugin::theConeRadius [private]

cone radius

Definition at line 80 of file CMSIterativeConePlugin.hh.

Referenced by description(), and run_clustering().

double fastjet::CMSIterativeConePlugin::theSeedThreshold [private]

seed threshold

Definition at line 81 of file CMSIterativeConePlugin.hh.

Referenced by description(), and run_clustering().

The documentation for this class was generated from the following files:
Generated on 26 Feb 2010 for fastjet by  doxygen 1.6.1