fastjet_example.cc File Reference

#include "fastjet/PseudoJet.hh"
#include "fastjet/ClusterSequence.hh"
#include <iostream>
#include <sstream>
#include <vector>
#include <cstdio>

Include dependency graph for fastjet_example.cc:

Go to the source code of this file.

Functions
void	print_jets (const fastjet::ClusterSequence &clust_seq, const vector< fastjet::PseudoJet > &jets)
	a function that pretty prints a list of jets
int	main (int argc, char **argv)
	an example program showing how to use fastjet

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Function Documentation

int main	(	int	argc,
		char **	argv
	)

an example program showing how to use fastjet

Definition at line 56 of file fastjet_example.cc.

References Best, fastjet::JetDefinition::description(), fastjet::E_scheme, fastjet::ClusterSequence::exclusive_jets(), fastjet::ClusterSequence::inclusive_jets(), fastjet::kt_algorithm, print_jets(), and fastjet::ClusterSequence::strategy_string().

                                  {
  
  vector<fastjet::PseudoJet> input_particles;
  
  // read in input particles
  double px, py , pz, E;
  while (cin >> px >> py >> pz >> E) {
    // create a fastjet::PseudoJet with these components and put it onto
    // back of the input_particles vector
    input_particles.push_back(fastjet::PseudoJet(px,py,pz,E)); 
  }
  
  // create an object that represents your choice of jet algorithm and 
  // the associated parameters
  double Rparam = 1.0;
  fastjet::Strategy strategy = fastjet::Best;
  fastjet::RecombinationScheme recomb_scheme = fastjet::E_scheme;
  fastjet::JetDefinition jet_def(fastjet::kt_algorithm, Rparam, recomb_scheme, strategy);

  // run the jet clustering with the above jet definition
  fastjet::ClusterSequence clust_seq(input_particles, jet_def);

  // tell the user what was done
  cout << "Ran " << jet_def.description() << endl;
  cout << "Strategy adopted by FastJet was "<<
       clust_seq.strategy_string()<<endl<<endl;

  // extract the inclusive jets with pt > 5 GeV
  double ptmin = 5.0;
  vector<fastjet::PseudoJet> inclusive_jets = clust_seq.inclusive_jets(ptmin);

  // print them out
  cout << "Printing inclusive jets with pt > "<< ptmin<<" GeV\n";
  cout << "---------------------------------------\n";
  print_jets(clust_seq, inclusive_jets);
  cout << endl;

  // extract the exclusive jets with dcut = 25 GeV^2 
  double dcut = 25.0;
  vector<fastjet::PseudoJet> exclusive_jets = clust_seq.exclusive_jets(dcut);

  // print them out
  cout << "Printing exclusive jets with dcut = "<< dcut<<" GeV^2\n";
  cout << "--------------------------------------------\n";
  print_jets(clust_seq, exclusive_jets);


}

void print_jets	(	const fastjet::ClusterSequence &	clust_seq,
		const vector< fastjet::PseudoJet > &	jets
	)

a function that pretty prints a list of jets

Definition at line 108 of file fastjet_example.cc.

References fastjet::ClusterSequence::constituents(), fastjet::d0::inline_maths::phi(), and fastjet::sorted_by_pt().

                                                        {

  // sort jets into increasing pt
  vector<fastjet::PseudoJet> sorted_jets = sorted_by_pt(jets);  

  // label the columns
  printf("%5s %15s %15s %15s %15s\n","jet #", "rapidity", 
         "phi", "pt", "n constituents");
  
  // print out the details for each jet
  for (unsigned int i = 0; i < sorted_jets.size(); i++) {
    int n_constituents = clust_seq.constituents(sorted_jets[i]).size();
    printf("%5u %15.8f %15.8f %15.8f %8u\n",
           i, sorted_jets[i].rap(), sorted_jets[i].phi(),
           sorted_jets[i].perp(), n_constituents);
  }

}