main38
Back to index.
// main38.cc is a part of the PYTHIA event generator.
// Copyright (C) 2024 Torbjorn Sjostrand.
// PYTHIA is licenced under the GNU GPL v2 or later, see COPYING for details.
// Please respect the MCnet Guidelines, see GUIDELINES for details.
// Keywords:
// Basic usage
// LHE file
// This is a simple test program.
// It illustrates how Les Houches Event File version 3.0 information
// can be extracted from pythia.info.
#include "Pythia8/Pythia.h"
using namespace Pythia8;
int main() {
// Generator
Pythia pythia;
// Stick with default values, so do not bother with a separate file
// for changes. However, do one change, to show readString in action.
pythia.readString("PartonLevel:MPI = off");
pythia.readString("HadronLevel:all = off");
// Initialize gzipped Les Houches Event File run.
pythia.readString("Beams:frameType = 4");
pythia.readString("Beams:LHEF = wbj_lhef3.lhe");
pythia.init();
// Check if LHEF3 reader exists.
bool hasRead = (pythia.info.LHEFversion() == 3);
// Print header read from LHEF.
cout << endl << "*****************************************************"
<< endl << " PRINT HEADER OF LHE FILE" << endl;
if (hasRead) cout << pythia.info.getHeaderBlock() << endl;
cout << "*****************************************************" << endl;
// Print extra LHEF v3 header information.
cout << endl << "*****************************************************"
<< endl << " RETRIEVE INITRWGT INFORMATION" << endl;
if (hasRead) {
const LHAinitrwgt* initrwgt = pythia.info.initrwgt;
cout << endl << "Attributes: " << endl;
for ( map<string,string>::const_iterator
it = initrwgt->attributes.begin();
it != initrwgt->attributes.end(); ++it )
cout << " Attribute: " << it->first << ". ." << it->second
<< endl;
cout << "Contents: " << initrwgt->contents << endl;
cout << endl << endl << " RETRIEVE WEIGHTGROUP INFORMATION" << endl;
map<string,LHAweightgroup> weightgroups = initrwgt->weightgroups;
for ( map<string,LHAweightgroup>::const_iterator
it = weightgroups.begin();
it != weightgroups.end(); ++it ) {
cout << " Weightgroup: " << it->first << endl;
for ( map<string,string>::const_iterator
it2 = it->second.attributes.begin();
it2 != it->second.attributes.end(); ++it2 ) {
cout << " Attribute: " << it2->first << ". ." << it2->second
<< endl;
}
cout << endl << " Retrieve weight information:" << endl;
map<string,LHAweight> weights = it->second.weights;
for ( map<string,LHAweight>::const_iterator
it2 = weights.begin(); it2 != weights.end(); ++it2 ) {
cout << " Weight: " << it2->first << endl;
for ( map<string,string>::const_iterator
it3 = it2->second.attributes.begin();
it3 != it2->second.attributes.end(); ++it3 ) {
cout << " Attribute: " << it3->first << ". ." << it3->second
<< endl;
}
cout << " Contents: " << it2->second.contents << endl;
}
}
}
cout << "*****************************************************" << endl;
// Print extra LHEF v3 initialization information.
cout << endl << "*****************************************************"
<< endl << " RETRIEVE GENERATOR INFORMATION" << endl;
unsigned int ngen = 0;
if (hasRead) ngen = pythia.info.generators->size();
cout << "Number of generator tags " << ngen << endl;
for (unsigned int igen = 0; igen < ngen; ++igen) {
cout << ". generator tag ." << igen << ". : ."
<< pythia.info.generators->at(igen).contents << ".\n";
for ( map<string, string>::const_iterator
it = pythia.info.generators->at(igen).attributes.begin();
it != pythia.info.generators->at(igen).attributes.end(); ++it )
cout << ". " << it->first << " ." << it->second;
cout << "\n";
}
cout << "*****************************************************" << endl;
// Begin event loop; generate until none left in input file.
for (int iEvent = 0; iEvent < 1000; ++iEvent) {
cout << endl << "Read event # " << iEvent << endl;
// Generate events, and check whether generation failed.
if (!pythia.next()) {
// If failure because reached end of file then exit event loop.
if (pythia.info.atEndOfFile()) break;
else continue;
}
// Print process-level event.
pythia.process.list();
// Print extra LHEF v3 event information.
cout << endl << "Print event # " << iEvent << endl;
cout << endl << "*****************************************************"
<< endl << " RETRIEVE EVENT INFORMATION" << endl;
if (hasRead) {
const map <string,string>* eventAttributes =
pythia.info.eventAttributes;
cout << endl << "Attributes:" << endl;
for ( map<string,string>::const_iterator it = eventAttributes->begin();
it != eventAttributes->end(); ++it )
cout << " Attribute\t" << it->first << " = " << it->second
<< endl;
}
cout << "*****************************************************" << endl;
// Print extra LHEF v3 event weight information.
cout << endl << "*****************************************************"
<< endl << " RETRIEVE WEIGHTS (DETAILED FORMAT) INFORMATION" << endl;
if (hasRead) {
int nwgt = pythia.info.rwgt->size();
cout << "Number of wgt tags " << nwgt << endl;
const map<string,double>* weights = pythia.info.weights_detailed;
for ( map<string,double>::const_iterator it = weights->begin();
it != weights->end(); ++it ) {
cout << it->first << " " << it->second << " " << endl;
}
cout << "Second option, from ordered vector:" << endl;
for ( int i = 0; i < int(pythia.info.weights_detailed_vector.size());
++i ) {
cout << "Weight " << i << " : "
<< pythia.info.weights_detailed_vector.at(i) << endl;
}
}
cout << "*****************************************************" << endl;
// Print extra LHEF v3 compressed format event weight information.
cout << endl << "*****************************************************"
<< endl << " RETRIEVE WEIGHTS (COMPRESSED FORMAT) INFORMATION"
<< endl;
if (hasRead) {
int nweights = pythia.info.weights->size();
cout << "Number of weights (only one tag!) " << nweights << endl;
const LHAweights* weights = pythia.info.weights;
cout << endl << "Attributes:" << endl;
for ( map<string,string>::const_iterator
it = weights->attributes.begin();
it != weights->attributes.end(); ++it )
cout << " Attribute\t" << it->first << " = " << it->second << endl;
cout << "Weights:" << endl;
for ( int i = 0; i < int(weights->weights.size()); ++i)
cout << " Weight\t" << weights->weights[i] << endl;
cout << endl << "Contents:" << weights->contents << endl;
cout << "Second option, from stored vector:" << endl;
for ( int i = 0; i < int(pythia.info.weights_compressed->size());
++i ) {
cout << "Weight\t" << i << " : "
<< pythia.info.weights_compressed->at(1) << endl;
}
}
cout << "*****************************************************" << endl;
// Print extra LHEF v3 scale information.
cout << endl << "*****************************************************"
<< endl << " RETRIEVE SCALES INFORMATION" << endl;
if (hasRead) {
const LHAscales* scales = pythia.info.scales;
cout << endl << "Attributes:" << endl;
for ( map<string,double>::const_iterator
it = scales->attributes.begin(); it != scales->attributes.end(); ++it )
cout << " Attribute\t" << it->first << " = " << it->second << endl;
cout << "Contents:" << scales->contents << endl;
}
cout << "*****************************************************" << endl;
// Print event comments.
cout << endl << "*****************************************************"
<< endl << " RETRIEVE EVENT COMMENTS" << endl;
if (hasRead) cout << pythia.info.getEventComments() << endl;
cout << "*****************************************************" << endl;
// End of event loop.
}
// Give statistics.
pythia.stat();
// Done.
return 0;
}