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// FastJet3.h is a part of the PYTHIA event generator.
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// Copyright (C) 2012 Torbjorn Sjostrand.
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// PYTHIA is licenced under the GNU GPL version 2, see COPYING for details.
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// Please respect the MCnet Guidelines, see GUIDELINES for details.
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// This header file written by Gavin Salam.
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#ifndef Pythia8_FastJet3_H
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#define Pythia8_FastJet3_H
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//----------------------------------------------------------------------
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/// \file FastJet3Pythia8.hh
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/// Code providing an interface for FastJet 3 to make use of Pythia8
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/// particles and momenta. Given a
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/// Pythia8::Particle py8_particle;
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/// fastjet::PseudoJet fj_particle = py8_particle;
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/// A copy of the Pythia8::Particle can then be accessed as
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/// fj_particle.user_info<Pythia8::Particle>()
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/// so that one can obtain information about the particle such as
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/// fj_particle.user_info<Pythia8::Particle>().status();
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/// fj_particle.user_info<Pythia8::Particle>().charge();
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/// etc. Note that because the construction of a PseudoJet from the
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/// Pythia8 particle involves taking a copy of the whole particle
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/// (which has a number of member variables), there will be a small
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/// time penalty at that point.
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/// This file also defines a number of selectors that act on such
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/// PseudoJets, such as
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/// SelectorIsCharged();
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/// SelectorId(int id);
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/// so that one can for example write
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/// vector<PseudoJet> charged_constituents
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/// = SelectorIsCharged()(jet.constituents());
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/// The full list of Pythia8-specific selectors is to be found at the
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/// end of this file. They can be combined with each other and with
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/// FastJet selectors using standard boolean operators. They are all
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/// in the fastjet namespace.
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/// If you do not need the above facilities, then you may instead
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/// construct the PseudoJet from the pythia8 particle's 4-vector
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/// PseudoJet fj_particle = py8_particle.p();
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/// NB: this code is entirely given as an include file. If compilation
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/// time is critical for your application, you may wish to split it
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/// into separate .cc and .hh files.
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// ----------------------------------------------------------------------
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// Copyright 2011 by Matteo Cacciari, Gavin Salam and Gregory
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// Soyez. Permission is granted to redistribute this file and modify
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// it, as long as this notice is retained and any changes are clearly
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// marked. No warranties are provided!
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// ----------------------------------------------------------------------
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#include "fastjet/config.h" // will allow a test for FJ3
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#include "fastjet/ClusterSequence.hh" // also gives PseudoJet & JetDefinition
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#include "fastjet/Selector.hh"
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#include "Event.h" // this is what we need from Pythia8
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// FASTJET_VERSION is only defined from version 3 onwards so we can
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// use it to test that we have a sufficiently recent version
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#ifndef FASTJET_VERSION
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#error "FastJet 3 is required in order to obtain the features of this interface"
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FASTJET_BEGIN_NAMESPACE // place the code here inside the FJ namespace
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/// \class Py8Particle
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/// A class derived from a pythia 8 particle and that also derives
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/// from PseudoJet::UserInfoBase, so that it can be used as UserInfo
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/// inside PseudoJets, but also be cast back to the Pythia8 particle
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class Py8Particle: public Pythia8::Particle,
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public PseudoJet::UserInfoBase {
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Py8Particle(const Pythia8::Particle & particle) : Particle(particle) {}
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/// specialization of the PseudoJet constructor so that it can take a
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/// pythia8 particle (and makes a copy of it as user info);
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inline PseudoJet::PseudoJet(const Pythia8::Particle & particle) {
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reset(particle.px(),particle.py(),particle.pz(), particle.e());
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set_user_info(new Py8Particle(particle));
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/// specialization of the PseudoJet constructor so that it can take a
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/// pythia8 Vec4. There is then no particular user info available.
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inline PseudoJet::PseudoJet(const Pythia8::Vec4 & particle) {
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reset(particle.px(),particle.py(),particle.pz(), particle.e());
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/// \class SelectorWorkerPy8
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/// A template class to help with the creation of Selectors for Pythia
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/// particle properties. It's not necessary to understand how this
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/// works in order to use the selectors. See below for the actual list
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/// (But if you're curious, essentially it stores a pointer to a
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/// member function of Pythia8::Particle, and when called to select
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/// particles, executes it and checks the return value is equal to
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/// that requested in the constructor).
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template<class T> class SelectorWorkerPy8 : public SelectorWorker {
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/// the typedef helps with the notation for member function pointers
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typedef T (Pythia8::Particle::*Py8ParticleFnPtr)() const;
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/// c'tor, which takes the member fn pointer and the return value
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/// that it should be equal to
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SelectorWorkerPy8(Py8ParticleFnPtr member_fn_ptr, T value) :
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_member_fn_ptr(member_fn_ptr), _value(value) {};
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/// the one function from SelectorWorker that must be overloaded to
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/// get functioning selection. It makes sure that the PseudoJet
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/// actually has Pythia8::Particle user info before checking
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bool pass(const PseudoJet & p) const {
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const Pythia8::Particle * py8_particle
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= dynamic_cast<const Pythia8::Particle *>(p.user_info_ptr());
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if (py8_particle == 0) {
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return false; // no info, so false
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return (py8_particle->*_member_fn_ptr)() == _value;
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Py8ParticleFnPtr _member_fn_ptr;
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/// @name Boolean FJ3/PY8 Selectors
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/// A series of selectors for boolean properties of PseudoJets with
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/// Pythia8::Particle information; PseudoJets without
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/// Pythia8::Particle structure never pass these selectors.
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inline Selector SelectorIsFinal () {return
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Selector(new SelectorWorkerPy8<bool>(&Pythia8::Particle::isFinal , true));}
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inline Selector SelectorIsCharged () {return
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Selector(new SelectorWorkerPy8<bool>(&Pythia8::Particle::isCharged , true));}
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inline Selector SelectorIsNeutral () {return
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Selector(new SelectorWorkerPy8<bool>(&Pythia8::Particle::isNeutral , true));}
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inline Selector SelectorIsResonance() {return
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Selector(new SelectorWorkerPy8<bool>(&Pythia8::Particle::isResonance, true));}
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inline Selector SelectorIsVisible () {return
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Selector(new SelectorWorkerPy8<bool>(&Pythia8::Particle::isVisible , true));}
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inline Selector SelectorIsLepton () {return
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Selector(new SelectorWorkerPy8<bool>(&Pythia8::Particle::isLepton , true));}
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inline Selector SelectorIsQuark () {return
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Selector(new SelectorWorkerPy8<bool>(&Pythia8::Particle::isQuark , true));}
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inline Selector SelectorIsGluon () {return
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Selector(new SelectorWorkerPy8<bool>(&Pythia8::Particle::isGluon , true));}
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inline Selector SelectorIsDiquark () {return
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Selector(new SelectorWorkerPy8<bool>(&Pythia8::Particle::isDiquark , true));}
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inline Selector SelectorIsParton () {return
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Selector(new SelectorWorkerPy8<bool>(&Pythia8::Particle::isParton , true));}
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inline Selector SelectorIsHadron () {return
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Selector(new SelectorWorkerPy8<bool>(&Pythia8::Particle::isHadron , true));}
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/// @name Integer FJ3/PY8 Selectors
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/// A series of selectors for integer properties of PseudoJets with
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/// Pythia8::Particle information; PseudoJets without
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/// Pythia8::Particle structure never pass these selectors.
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inline Selector SelectorId (int i) {return
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Selector(new SelectorWorkerPy8<int>(&Pythia8::Particle::id , i));}
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inline Selector SelectorIdAbs (int i) {return
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Selector(new SelectorWorkerPy8<int>(&Pythia8::Particle::idAbs , i));}
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inline Selector SelectorStatus (int i) {return
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Selector(new SelectorWorkerPy8<int>(&Pythia8::Particle::status , i));}
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inline Selector SelectorStatusAbs(int i) {return
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Selector(new SelectorWorkerPy8<int>(&Pythia8::Particle::statusAbs, i));}
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FASTJET_END_NAMESPACE
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#endif // Pythia8_FastJet3_H
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include/FastJet3.h
