HepMC3 event record library: basic_tree.cc

HepMC3 event record library

basic_tree.cc

Basic example of building HepMC3 tree by hand.

Basic example of building HepMC3 tree by hand Based on HepMC2/examples/example_BuildEventFromScratch.cc

// -*- C++ -*-
//
// This file is part of HepMC
// Copyright (C) 2014-2023 The HepMC collaboration (see AUTHORS for details)
//
/// @example basic_tree.cc
/// @brief Basic example of building HepMC3 tree by hand
///
/// Based on HepMC2/examples/example_BuildEventFromScratch.cc
#include "HepMC3/GenEvent.h"
#include "HepMC3/GenVertex.h"
#include "HepMC3/GenParticle.h"
#include "HepMC3/Print.h"
#include "HepMC3/Selector.h"
using namespace HepMC3;
/** Main program */
int main() {
//
// In this example we will place the following event into HepMC "by hand"
//
// name status pdg_id parent Px Py Pz Energy Mass
// 1 !p+! 3 2212 0,0 0.000 0.000 7000.000 7000.000 0.938
// 3 !p+! 3 2212 0,0 0.000 0.000-7000.000 7000.000 0.938
//=========================================================================
// 2 !d! 3 1 1,1 0.750 -1.569 32.191 32.238 0.000
// 4 !u~! 3 -2 2,2 -3.047 -19.000 -54.629 57.920 0.000
// 5 !W-! 3 -24 1,2 1.517 -20.68 -20.605 85.925 80.799
// 6 !gamma! 1 22 1,2 -3.813 0.113 -1.833 4.233 0.000
// 7 !d! 1 1 5,5 -2.445 28.816 6.082 29.552 0.010
// 8 !u~! 1 -2 5,5 3.962 -49.498 -26.687 56.373 0.006
// now we build the graph, which will looks like
// p7 #
// p1 / #
// \v1__p2 p5---v4 #
// \_v3_/ \ #
// / \ p8 #
// v2__p4 \ #
// / p6 #
// p3 #
// #
GenEvent evt(Units::GEV,Units::MM);
// px py pz e pdgid status
GenParticlePtr p1 = std::make_shared<GenParticle>( FourVector( 0.0, 0.0, 7000.0, 7000.0 ),2212, 3 );
GenParticlePtr p2 = std::make_shared<GenParticle>( FourVector( 0.750, -1.569, 32.191, 32.238), 1, 3 );
GenParticlePtr p3 = std::make_shared<GenParticle>( FourVector( 0.0, 0.0, -7000.0, 7000.0 ),2212, 3 );
GenParticlePtr p4 = std::make_shared<GenParticle>( FourVector(-3.047,-19.0, -54.629, 57.920), -2, 3 );
GenVertexPtr v1 = std::make_shared<GenVertex>();
v1->add_particle_in (p1);
v1->add_particle_out(p2);
evt. add_vertex(v1);
// Set vertex status if needed
v1->set_status(4);
GenVertexPtr v2 = std::make_shared<GenVertex>();
v2->add_particle_in (p3);
v2->add_particle_out(p4);
evt.add_vertex(v2);
GenVertexPtr v3 = std::make_shared<GenVertex>();
v3->add_particle_in(p2);
v3->add_particle_in(p4);
evt.add_vertex(v3);
GenParticlePtr p5 = std::make_shared<GenParticle>( FourVector(-3.813, 0.113, -1.833, 4.233), 22, 1 );
GenParticlePtr p6 = std::make_shared<GenParticle>( FourVector( 1.517,-20.68, -20.605,85.925), -24, 3 );
v3->add_particle_out(p5);
v3->add_particle_out(p6);
GenVertexPtr v4 =std:: make_shared<GenVertex>();
v4->add_particle_in (p6);
evt.add_vertex(v4);
GenParticlePtr p7 = std::make_shared<GenParticle>( FourVector(-2.445, 28.816, 6.082,29.552), 1, 1 );
GenParticlePtr p8 = std::make_shared<GenParticle>( FourVector( 3.962,-49.498,-26.687,56.373), -2, 1 );
v4->add_particle_out(p7);
v4->add_particle_out(p8);
//
// Example of adding event attributes
//
std::shared_ptr<GenPdfInfo> pdf_info = std::make_shared<GenPdfInfo>();
evt. add_attribute("GenPdfInfo",pdf_info);
pdf_info->set(1,2,3.4,5.6,7.8,9.0,1.2,3,4);
std::shared_ptr<GenHeavyIon> heavy_ion = std::make_shared<GenHeavyIon>();
evt.add_attribute("GenHeavyIon",heavy_ion);
heavy_ion->set( 1,2,3,4,5,6,7,8,9,0.1,2.3,4.5,6.7);
std::shared_ptr<GenCrossSection> cross_section = std::make_shared<GenCrossSection>();
evt.add_attribute("GenCrossSection",cross_section);
cross_section->set_cross_section(1.2,3.4);
//
// Example of manipulating the attributes
//
std::cout << std::endl << " Manipulating attributes:" << std::endl;
// get attribute
std::shared_ptr<GenCrossSection> cs = evt. attribute<GenCrossSection>("GenCrossSection");
// if attribute exists - do something with it
if(cs) {
cs->set_cross_section(-1.0,0.0);
Print::line(cs);
}
else std::cout << "Problem accessing attribute!" <<std::endl;
// remove attribute
evt. remove_attribute("GenCrossSection");
evt.remove_attribute("GenCrossSection"); // This call will do nothing
// now this should be null
cs = evt.attribute<GenCrossSection>("GenCrossSection");
if(!cs){std::cout << "Successfully removed attribute" <<std::endl;}
else {std::cout << "Problem removing attribute!" <<std::endl;}
//
// Example of adding attributes and finding particles with attributes
//
std::shared_ptr<Attribute> tool1 = std::make_shared<IntAttribute>(1);
std::shared_ptr<Attribute> tool999 = std::make_shared<IntAttribute>(999);
std::shared_ptr<Attribute> test_attribute = std::make_shared<StringAttribute>("test attribute");
std::shared_ptr<Attribute> test_attribute2 = std::make_shared<StringAttribute>("test attribute2");
p2->add_attribute( "tool" , tool1 );
p2->add_attribute( "other" , test_attribute );
p4->add_attribute( "tool" , tool1 );
p6->add_attribute( "tool" , tool999 );
p6->add_attribute( "other" , test_attribute2 );
v3->add_attribute( "vtx_att" , test_attribute );
v4->add_attribute( "vtx_att" , test_attribute2 );
/* TODO: Make this code portable
std::cout << std::endl << "Find all particles with attribute 'tool' "<< std::endl;
std::cout << "(should return particles 2,4,6):" << std::endl;
/// @todo can we add some utility funcs to simplify creation of Features from Attributes and check they exist.
/// Features and Attributes are quite similar concepts anyway, can they be unified (but Features can also be
/// non-attribute-like e.g. pT, rapidity or any quantity it is possible to obtain from a particle)
for(ConstGenParticlePtr p: applyFilter(Selector::ATTRIBUTE("tool"), evt.particles())){
Print::line(p);
}
std::cout <<std::endl << "Find all particles with attribute 'tool' equal 1 "<< std::endl;
std::cout << "(should return particles 2,4):" <<std::endl;
for(ConstGenParticlePtr p: applyFilter(Selector::ATTRIBUTE("tool") && Selector::ATTRIBUTE("tool") == tool1, evt.particles())){
Print::line(p);
}
std::cout << std::endl << "Find all particles with a string attribute 'other' equal 'test attribute' "<< std::endl;
std::cout << "(should return particle 2):" << std::endl;
for(ConstGenParticlePtr p: applyFilter(Selector::ATTRIBUTE("other") && Selector::ATTRIBUTE("other") == "test_attribute", evt.particles())){
Print::line(p);
}
*/
std::cout << std::endl << "Offsetting event position by 5,5,5,5" << std::endl;
evt. shift_position_by( FourVector(5,5,5,5) );
Print::listing(evt);
std::cout << std::endl << "Printing full content of the GenEvent object " << std::endl
<< "(including particles and vertices in one-line format):" << std::endl << std::endl;
Print::content(evt);
std::cout <<std::endl << "Now: removing particle with id 6 and printing again:" <<std::endl <<std::endl;
evt. remove_particle(p6);
Print::listing(evt);
Print::content(evt);
std::cout <<std::endl << "Now: removing beam particles, leaving an empty event" <<std::endl <<std::endl;
evt. remove_particles( evt. beams() );
Print::listing(evt);
Print::content(evt);
return 0;
}
GenEvent.h
Definition of class GenEvent.
GenParticle.h
Definition of class GenParticle.
GenVertex.h
Definition of class GenVertex.
Print.h
Definition of static class Print.
Selector.h
definition of Selector class
HepMC3::FourVector
Generic 4-vector.
Definition FourVector.h:36
HepMC3::GenCrossSection
Stores additional information about cross-section.
Definition GenCrossSection.h:42
HepMC3::GenEvent
Stores event-related information.
Definition GenEvent.h:47
HepMC3::GenEvent::attribute
std::shared_ptr< T > attribute(const std::string &name, const int &id=0) const
Get attribute of type T.
Definition GenEvent.h:420
HepMC3::GenEvent::add_vertex
void add_vertex(GenVertexPtr v)
Add vertex.
Definition GenEvent.cc:99
HepMC3::GenEvent::remove_particles
void remove_particles(std::vector< GenParticlePtr > v)
Remove a set of particles.
Definition GenEvent.cc:182
HepMC3::GenEvent::shift_position_by
void shift_position_by(const FourVector &delta)
Shift position of all vertices in the event by delta.
Definition GenEvent.cc:438
HepMC3::GenEvent::beams
std::vector< ConstGenParticlePtr > beams() const
Vector of beam particles.
Definition GenEvent.cc:429
HepMC3::GenEvent::add_attribute
void add_attribute(const std::string &name, const std::shared_ptr< Attribute > &att, const int &id=0)
Definition GenEvent.cc:797
HepMC3::GenEvent::remove_attribute
void remove_attribute(const std::string &name, const int &id=0)
Remove attribute.
Definition GenEvent.cc:602
HepMC3::GenEvent::remove_particle
void remove_particle(GenParticlePtr p)
Remove particle from the event.
Definition GenEvent.cc:119
HepMC3::Print::content
static void content(std::ostream &os, const GenEvent &event)
Print content of all GenEvent containers.
Definition Print.cc:17
HepMC3::Print::listing
static void listing(std::ostream &os, const GenEvent &event, unsigned short precision=2)
Print event in listing (HepMC2) format.
Definition Print.cc:52
HepMC3::Print::line
static void line(std::ostream &os, const GenEvent &event, bool attributes=false)
Print one-line info.
Definition Print.cc:204
HepMC3
HepMC3 main namespace.
Definition AnalysisExample.h:24