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//----------------------------------------------------------------------
// Example on how to use the SoftKiller
//
// run it with
// ./example < ../data/Pythia-Zp2jets-lhc-pileup-1ev.dat
//----------------------------------------------------------------------
// $Id: example.cc 769 2015-02-20 14:48:49Z gsalam $
//
// Copyright (c) 2014-, Matteo Cacciari, Gavin. P. Salam and Gregory Soyez
//
//----------------------------------------------------------------------
// This file is part of FastJet contrib.
//
// It is free software; you can redistribute it and/or modify it under
// the terms of the GNU General Public License as published by the
// Free Software Foundation; either version 2 of the License, or (at
// your option) any later version.
//
// It is distributed in the hope that it will be useful, but WITHOUT
// ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
// or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public
// License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this code. If not, see <http://www.gnu.org/licenses/>.
//----------------------------------------------------------------------
#include <iostream>
#include <iomanip>
#include "fastjet/ClusterSequence.hh"
#include "SoftKiller.hh" // In external code, this should be fastjet/contrib/SoftKiller.hh
using namespace std;
using namespace fastjet;
// forward declaration to make things clearer
void read_event(vector<PseudoJet> &hard_event, vector<PseudoJet> &full_event);
//----------------------------------------------------------------------
int main(){
// read in input particles
//
// since we use here simulated data we can split the hard event
// from the full (i.e. with pileup added) one
//
// (see also example 07 in FastJet)
//----------------------------------------------------------
vector<PseudoJet> hard_event, full_event;
read_event(hard_event, full_event);
// keep the particles up to 5 units in rapidity
double rapmax = 5.0;
hard_event = SelectorAbsRapMax(rapmax)(hard_event);
full_event = SelectorAbsRapMax(rapmax)(full_event);
// do the clustering and get the jets from the hard event
// as well as for the full event without applying any
// subtraction
//----------------------------------------------------------
JetDefinition jet_def(antikt_algorithm, 0.4);
ClusterSequence clust_seq_hard(hard_event, jet_def);
ClusterSequence clust_seq_full(full_event, jet_def);
Selector sel_jets = SelectorNHardest(2) * SelectorAbsRapMax(3.0);
vector<PseudoJet> hard_jets = sel_jets(clust_seq_hard.inclusive_jets());
vector<PseudoJet> full_jets = sel_jets(clust_seq_full.inclusive_jets());
// now apply the soft killerto the full event
// Then cluster the resulting event
//----------------------------------------------------------
double grid_size = 0.4;
contrib::SoftKiller soft_killer(rapmax, grid_size);
//contrib::SoftKiller soft_killer(-0.0, 4.0, 0.5, 0.3);
double pt_threshold;
vector<PseudoJet> soft_killed_event;
soft_killer.apply(full_event, soft_killed_event, pt_threshold);
cout << "# Ran the following soft killer: " << soft_killer.description() << endl;
// alternative, more compact invocation
//vector<PseudoJet> soft_killed_event = soft_killer(full_event);
ClusterSequence clust_seq_kill(soft_killed_event, jet_def);
vector<PseudoJet> kill_jets = sel_jets(clust_seq_kill.inclusive_jets());
cout << setprecision(4);
cout << "Soft Killer applied a pt threshold of " << pt_threshold << endl;
// run things and print the result
//----------------------------------------------------------
cout << "# original hard jets" << endl;
for (unsigned int i=0; i<hard_jets.size(); i++){
const PseudoJet &jet = hard_jets[i];
cout << "pt = " << jet.pt()
<< ", rap = " << jet.rap()
<< ", mass = " << jet.m() << endl;
}
cout << endl;
cout << "# original full jets" << endl;
for (unsigned int i=0; i<full_jets.size(); i++){
const PseudoJet &jet = full_jets[i];
cout << "pt = " << jet.pt()
<< ", rap = " << jet.rap()
<< ", mass = " << jet.m() << endl;
}
cout << endl;
cout << "# jets after applying the soft killer" << endl;
for (unsigned int i=0; i<kill_jets.size(); i++){
const PseudoJet &jet = kill_jets[i];
cout << "pt = " << jet.pt()
<< ", rap = " << jet.rap()
<< ", mass = " << jet.m() << endl;
}
cout << endl;
return 0;
}
//------------------------------------------------------------------------
// read the event with and without pileup
void read_event(vector<PseudoJet> &hard_event, vector<PseudoJet> &full_event){
string line;
int nsub = 0; // counter to keep track of which sub-event we're reading
while (getline(cin, line)) {
istringstream linestream(line);
// take substrings to avoid problems when there are extra "pollution"
// characters (e.g. line-feed).
if (line.substr(0,4) == "#END") {break;}
if (line.substr(0,9) == "#SUBSTART") {
// if more sub events follow, make copy of first one (the hard one) here
if (nsub == 1) hard_event = full_event;
nsub += 1;
}
if (line.substr(0,1) == "#") {continue;}
double px,py,pz,E;
linestream >> px >> py >> pz >> E;
PseudoJet particle(px,py,pz,E);
// push event onto back of full_event vector
full_event.push_back(particle);
}
// if we have read in only one event, copy it across here...
if (nsub == 1) hard_event = full_event;
// if there was nothing in the event
if (nsub == 0) {
cerr << "Error: read empty event\n";
exit(-1);
}
cout << "# " << nsub-1 << " pileup events on top of the hard event" << endl;
}

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