FastJet 3.0.2
CDFMidPointPlugin.cc
00001 //STARTHEADER
00002 // $Id: CDFMidPointPlugin.cc 2777 2011-11-25 15:01:56Z soyez $
00003 //
00004 // Copyright (c) 2005-2011, Matteo Cacciari, Gavin P. Salam and Gregory Soyez
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, see <http://www.gnu.org/licenses/>.
00026 //----------------------------------------------------------------------
00027 //ENDHEADER
00028 
00029 #include "fastjet/CDFMidPointPlugin.hh"
00030 #include "fastjet/ClusterSequence.hh"
00031 #include "fastjet/Error.hh"
00032 #include <sstream>
00033 
00034 // CDF stuff
00035 #include "MidPointAlgorithm.hh"
00036 #include "PhysicsTower.hh"
00037 #include "Cluster.hh"
00038 
00039 FASTJET_BEGIN_NAMESPACE      // defined in fastjet/internal/base.hh
00040 
00041 using namespace std;
00042 using namespace cdf;
00043 
00044 bool CDFMidPointPlugin::_first_time = true;
00045 
00046 string CDFMidPointPlugin::description () const {
00047   ostringstream desc;
00048   
00049   string sm_scale_string = "split-merge uses ";
00050   switch(_sm_scale) {
00051   case SM_pt:
00052     sm_scale_string += "pt";
00053     break;
00054   case SM_Et:
00055     sm_scale_string += "Et";
00056     break;
00057   case SM_mt:
00058     sm_scale_string += "mt";
00059     break;
00060   case SM_pttilde:
00061     sm_scale_string += "pttilde (scalar sum of pts)";
00062     break;
00063   default:
00064     ostringstream err;
00065     err << "Unrecognized split-merge scale choice = " << _sm_scale;
00066     throw Error(err.str());
00067   }
00068 
00069   
00070   if (cone_area_fraction() == 1) {
00071     desc << "CDF MidPoint jet algorithm, with " ;
00072   } else {
00073     desc << "CDF MidPoint+Searchcone jet algorithm, with ";
00074   }
00075   desc << "seed_threshold = "     << seed_threshold     () << ", "
00076        << "cone_radius = "        << cone_radius        () << ", "
00077        << "cone_area_fraction = " << cone_area_fraction () << ", " 
00078        << "max_pair_size = "      << max_pair_size      () << ", "
00079        << "max_iterations = "     << max_iterations     () << ", "
00080        << "overlap_threshold  = " << overlap_threshold  () << ", "
00081        << sm_scale_string ;
00082 
00083   return desc.str();
00084 }
00085 
00086 
00087 void CDFMidPointPlugin::run_clustering(ClusterSequence & clust_seq) const {
00088   // print a banner if we run this for the first time
00089   _print_banner(clust_seq.fastjet_banner_stream());
00090  
00091   // create the physics towers needed by the CDF code
00092   vector<PhysicsTower> towers;
00093   towers.reserve(clust_seq.jets().size());
00094   for (unsigned i = 0; i < clust_seq.jets().size(); i++) {
00095     LorentzVector fourvect(clust_seq.jets()[i].px(),
00096                            clust_seq.jets()[i].py(),
00097                            clust_seq.jets()[i].pz(),
00098                            clust_seq.jets()[i].E());
00099     PhysicsTower tower(fourvect);
00100     // misuse one of the indices for tracking, since the MidPoint
00101     // implementation doesn't seem to make use of these indices
00102     tower.calTower.iEta = i;
00103     towers.push_back(tower);
00104   }
00105 
00106   // prepare the CDF algorithm
00107   MidPointAlgorithm m(_seed_threshold,_cone_radius,_cone_area_fraction,
00108                       _max_pair_size,_max_iterations,_overlap_threshold,
00109                       MidPointAlgorithm::SplitMergeScale(_sm_scale));
00110     
00111   // run the CDF algorithm
00112   std::vector<Cluster> jets;
00113   m.run(towers,jets);
00114 
00115 
00116   // now transfer the jets back into our own structure -- we will
00117   // mimic the cone code with a sequential recombination sequence in
00118   // which the jets are built up by adding one particle at a time
00119   for(vector<Cluster>::const_iterator jetIter = jets.begin(); 
00120                                       jetIter != jets.end(); jetIter++) {
00121     const vector<PhysicsTower> & tower_list = jetIter->towerList;
00122     int jet_k = tower_list[0].calTower.iEta;
00123   
00124     int ntow = int(jetIter->towerList.size());
00125     for (int itow = 1; itow < ntow; itow++) {
00126       int jet_i = jet_k;
00127       // retrieve our misappropriated index for the jet
00128       int jet_j = tower_list[itow].calTower.iEta;
00129       // do a fake recombination step with dij=0
00130       double dij = 0.0;
00131       clust_seq.plugin_record_ij_recombination(jet_i, jet_j, dij, jet_k);
00132     }
00133   
00134     // NB: put a sensible looking d_iB just to be nice...
00135     double d_iB = clust_seq.jets()[jet_k].perp2();
00136     clust_seq.plugin_record_iB_recombination(jet_k, d_iB);
00137   }
00138 
00139 
00140   // following code is for testing only
00141   //cout << endl;
00142   //for(vector<Cluster>::const_iterator jetIter = jets.begin(); 
00143   //                                    jetIter != jets.end(); jetIter++) {
00144   //  cout << jetIter->fourVector.pt() << " " << jetIter->fourVector.y() << endl;
00145   //}
00146   //cout << "-----------------------------------------------------\n";
00147   //vector<PseudoJet> ourjets(clust_seq.inclusive_jets());
00148   //for (vector<PseudoJet>::const_reverse_iterator ourjet = ourjets.rbegin();
00149   //     ourjet != ourjets.rend(); ourjet++) {
00150   //  cout << ourjet->perp() << " " << ourjet->rap() << endl;
00151   //}
00152   //cout << endl;
00153 }
00154 
00155 // print a banner for reference to the 3rd-party code
00156 void CDFMidPointPlugin::_print_banner(ostream *ostr) const{
00157   if (! _first_time) return;
00158   _first_time=false;
00159 
00160   // make sure the user has not set the banner stream to NULL
00161   if (!ostr) return;  
00162 
00163   (*ostr) << "#-------------------------------------------------------------------------" << endl;
00164   (*ostr) << "# You are running the CDF MidPoint plugin for FastJet                     " << endl;
00165   (*ostr) << "# This is based on an implementation provided by Joey Huston.             " << endl;
00166   (*ostr) << "# If you use this plugin, please cite                                     " << endl;
00167   (*ostr) << "#   G. C. Blazey et al., hep-ex/0005012.                                  " << endl;
00168   (*ostr) << "# in addition to the usual FastJet reference.                             " << endl;
00169   (*ostr) << "#-------------------------------------------------------------------------" << endl;
00170 
00171   // make sure we really have the output done.
00172   ostr->flush();
00173 }
00174 
00175 FASTJET_END_NAMESPACE      // defined in fastjet/internal/base.hh
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