run_jet_finder.cc

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00001 //STARTHEADER
00002 // $Id: run_jet_finder.cc 432 2007-01-23 12:12:59Z salam $
00003 //
00004 // Copyright (c) 2005-2006, Matteo Cacciari and Gavin Salam
00005 //
00006 //----------------------------------------------------------------------
00007 // This file is part of FastJet.
00008 //
00009 //  FastJet is free software; you can redistribute it and/or modify
00010 //  it under the terms of the GNU General Public License as published by
00011 //  the Free Software Foundation; either version 2 of the License, or
00012 //  (at your option) any later version.
00013 //
00014 //  The algorithms that underlie FastJet have required considerable
00015 //  development and are described in hep-ph/0512210. If you use
00016 //  FastJet as part of work towards a scientific publication, please
00017 //  include a citation to the FastJet paper.
00018 //
00019 //  FastJet is distributed in the hope that it will be useful,
00020 //  but WITHOUT ANY WARRANTY; without even the implied warranty of
00021 //  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
00022 //  GNU General Public License for more details.
00023 //
00024 //  You should have received a copy of the GNU General Public License
00025 //  along with FastJet; if not, write to the Free Software
00026 //  Foundation, Inc.:
00027 //      59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
00028 //----------------------------------------------------------------------
00029 //ENDHEADER
00030 
00031 #include "fastjet/PseudoJet.hh"
00032 #include "fastjet/ClusterSequence.hh"
00033 #include<iostream> // needed for io
00034 #include<sstream>  // needed for internal io
00035 #include<vector> 
00036 
00037 using namespace std;
00038 
00039 // a declaration of a function that pretty prints a list of jets
00040 void print_jets (const fastjet::ClusterSequence &, 
00041                  const vector<fastjet::PseudoJet> &);
00042 
00043 
00044 
00047 void run_jet_finder (const vector<fastjet::PseudoJet> & input_particles,
00048                      const fastjet::JetDefinition & jet_def) {
00049   
00050   // run the jet clustering with the above jet definition
00051   fastjet::ClusterSequence clust_seq(input_particles, jet_def);
00052 
00053   // tell the user what was done
00054   cout << "Ran " << jet_def.description() << endl;
00055 
00056   // extract the inclusive jets with pt > 5 GeV
00057   double ptmin = 5.0;
00058   vector<fastjet::PseudoJet> inclusive_jets = clust_seq.inclusive_jets(ptmin);
00059 
00060   // print them out
00061   cout << "Printing inclusive jets with pt > "<< ptmin<<" GeV\n";
00062   cout << "---------------------------------------\n";
00063   print_jets(clust_seq, inclusive_jets);
00064   cout << endl;
00065 
00066   // print out unclustered stuff
00067   cout << clust_seq.unclustered_particles().size() << " particles unclustered" << endl << endl;
00068 }
00069 
00070 
00071 //----------------------------------------------------------------------
00073 void read_input_particles(istream & input, 
00074                           vector<fastjet::PseudoJet> & input_particles){
00075 
00076   // read in input particles
00077   double px, py , pz, E;
00078   string line;
00079   while (getline(input, line)) {
00080     if (line.substr(0,1) == "#") {continue;}
00081     istringstream linestream(line);
00082     linestream >> px >> py >> pz >> E;
00083   // create a fastjet::PseudoJet with these components and put it onto
00084     // back of the input_particles vector
00085     input_particles.push_back(fastjet::PseudoJet(px,py,pz,E)); 
00086   }
00087   
00088 }
00089 
00090 //----------------------------------------------------------------------
00092 void print_jets (const fastjet::ClusterSequence & clust_seq, 
00093                  const vector<fastjet::PseudoJet> & jets) {
00094 
00095   // sort jets into increasing pt
00096   vector<fastjet::PseudoJet> sorted_jets = sorted_by_pt(jets);  
00097 
00098   // label the columns
00099   printf("%5s %15s %15s %15s %15s\n","jet #", "rapidity", 
00100          "phi", "pt", "n constituents");
00101   
00102   // print out the details for each jet
00103   for (unsigned int i = 0; i < sorted_jets.size(); i++) {
00104     int n_constituents = clust_seq.constituents(sorted_jets[i]).size();
00105     printf("%5u %15.8f %15.8f %15.8f %8u\n",
00106            i, sorted_jets[i].rap(), sorted_jets[i].phi(),
00107            sorted_jets[i].perp(), n_constituents);
00108   }
00109 
00110 }

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