Rivet_i.cxx

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/*
  Copyright (C) 2002-2025 CERN for the benefit of the ATLAS collaboration
*/
 
// Implementation file for Athena-Rivet interface
 
#include "Rivet_i.h"
#include "LogLevels.h"
 
#include "AtlasHepMC/GenEvent.h"
#include "TruthUtils/HepMCHelpers.h"
 
#include "GeneratorObjects/McEventCollection.h"
#include "AthenaKernel/errorcheck.h"
#include "PathResolver/PathResolver.h"
 
#include "GaudiKernel/IAppMgrUI.h"
#include "GaudiKernel/Bootstrap.h"
#include "GaudiKernel/ITHistSvc.h"
 
#include "Rivet/Rivet.hh"
#include "Rivet/Analysis.hh"
#include "Rivet/Config/RivetConfig.hh"
#include "Rivet/Tools/RivetYODA.hh"
 
 
#include <cstdlib>
#include <cstdio>
#include <memory>
#include <regex>
 

 
Rivet_i::Rivet_i(const std::string& name, ISvcLocator* pSvcLocator) :
  AthAlgorithm(name, pSvcLocator),
  m_needsConversion(false),
  m_analysisHandler(0),
  m_init(false)
{
  // Options
  declareProperty("McEventKey", m_genEventKey="GEN_EVENT");
  declareProperty("Analyses", m_analysisNames);
  declareProperty("CrossSection", m_crossSection=0.0);
  declareProperty("CrossSectionUncertainty", m_crossSection_uncert=0.0);
  declareProperty("Stream", m_stream="/Rivet");
  declareProperty("RunName", m_runname="");
  declareProperty("HistoFile", m_file="Rivet.yoda.gz");
  declareProperty("HistoPreload", m_preload="");
  declareProperty("AnalysisPath", m_anapath="");
  declareProperty("IgnoreBeamCheck", m_ignorebeams=false);
  declareProperty("DoRootHistos", m_doRootHistos=false);
  declareProperty("SkipWeights", m_skipweights=false);
  declareProperty("MatchWeights", m_matchWeights="");
  declareProperty("UnmatchWeights", m_unmatchWeights="");
  declareProperty("NominalWeightName", m_nominalWeightName="");
  declareProperty("WeightCap", m_weightcap=-1.0);
  declareProperty("AddMissingBeamParticles",m_patchBeams=false);
}
 
std::string getenv_str(const std::string& key) {
  char const* val = getenv(key.c_str());
  return val == NULL ? std::string() : std::string(val);
}
 
 
StatusCode Rivet_i::initialize ATLAS_NOT_THREAD_SAFE () {
  //                           ^ use of setenv
  ATH_MSG_INFO("Using Rivet version " << Rivet::version());
 
  ATH_CHECK(m_evtInfoKey.initialize());
 
  // Get tool for xAOD::Truth to HepMC::GenEvent conversion
  ATH_CHECK(m_xAODtoHepMCTool.retrieve());
 
 
  // Set RIVET_ANALYSIS_PATH based on alg setup
 
  // First set (overwrite, if necessary) the RIVET_ANALYSIS_PATH variable
  std::string env_rap(getenv_str("RIVET_ANALYSIS_PATH"));
  if (!m_anapath.empty()) {
    ATH_MSG_INFO("Setting Rivet plugin analyses loader env path: " << m_anapath);
    if (!env_rap.empty()) ATH_MSG_INFO("Overwriting environment's RIVET_ANALYSIS_PATH = " << env_rap << "!");
    setenv("RIVET_ANALYSIS_PATH", m_anapath.c_str(), 1);
  }
 
  // Get the final form of RIVET_ANALYSIS_PATH and talk about it
  env_rap = getenv_str("RIVET_ANALYSIS_PATH");
  if (!env_rap.empty()) ATH_MSG_DEBUG("Loading Rivet plugin analyses from env path: " << env_rap);
 
  // Set up analysis handler
  #if RIVET_VERSION_CODE >= 40100
  m_analysisHandler = new Rivet::AnalysisHandler();
  #else
  m_analysisHandler = new Rivet::AnalysisHandler(m_runname);
  #endif
  assert(m_analysisHandler);
 
  #if RIVET_VERSION_CODE >= 40000
  m_analysisHandler->setCheckBeams(!m_ignorebeams); //< Whether to do beam ID/energy consistency checks
  m_analysisHandler->matchWeightNames(m_matchWeights); //< Only run on a subset of the multi-weights
  m_analysisHandler->unmatchWeightNames(m_unmatchWeights); //< Veto a subset of the multi-weights
  #else
  m_analysisHandler->setIgnoreBeams(m_ignorebeams); //< Whether to do beam ID/energy consistency checks
  m_analysisHandler->selectMultiWeights(m_matchWeights); //< Only run on a subset of the multi-weights
  m_analysisHandler->deselectMultiWeights(m_unmatchWeights); //< Veto a subset of the multi-weights
  #endif
  m_analysisHandler->skipMultiWeights(m_skipweights); //< Only run on the nominal weight
  m_analysisHandler->setNominalWeightName(m_nominalWeightName);
  if (m_weightcap>0) m_analysisHandler->setWeightCap(m_weightcap);
 
  // Set Rivet native log level to match Athena
  Rivet::Log::setLevel("Rivet", rivetLevel(msg().level()));
 
  // Get all available analysis names
  if (msgLvl(MSG::VERBOSE)) {
    std::vector<std::string> analysisNames = Rivet::AnalysisLoader::analysisNames();
    ATH_MSG_VERBOSE("List of available Rivet analyses:");
    for (const std::string& a : analysisNames)  ATH_MSG_VERBOSE(" " + a);
  }
 
  // Add analyses
  for (const std::string& a : m_analysisNames) {
    ATH_MSG_INFO("Loading Rivet analysis " << a);
    m_analysisHandler->addAnalysis(a);
    Rivet::Log::setLevel("Rivet.Analysis."+a, rivetLevel(msg().level()));
  }
 
  // Initialise Rivet
  // m_analysisHandler->init();
 
  //load a pre-existing yoda file to initialize histograms
  if (m_preload!= "") {
    m_analysisHandler->readData(m_preload);
  }
 
  return StatusCode::SUCCESS;
}
 
 
StatusCode Rivet_i::execute(const EventContext& ctx) {
  ATH_MSG_DEBUG("Rivet_i execute");
 
 
  m_needsConversion = !evtStore()->contains<McEventCollection>(m_genEventKey);
  ATH_MSG_DEBUG("Rivet_i needs xAOD::Truth to HepMC::GenEvent conversion? " << m_needsConversion);
 
  std::unique_ptr<HepMC::GenEvent> checkedEvent;
  if (m_needsConversion) {
    const xAOD::TruthEventContainer* truthCollection = nullptr;
    if (evtStore()->retrieve(truthCollection, "TruthEvents").isFailure()) {
      ATH_MSG_ERROR("Could not retrieve TruthEvents collection, aborting.");
      return StatusCode::FAILURE;
    }
 
    SG::ReadHandle<xAOD::EventInfo> eventInfo(m_evtInfoKey, ctx);
    ATH_MSG_DEBUG("Attempt xAOD::Truth to HepMC::GenEvent conversion.");
    std::vector<HepMC::GenEvent>&& hepmc_evts = m_xAODtoHepMCTool->getHepMCEvents(truthCollection, eventInfo.cptr());
 
    if (hepmc_evts.empty()) {
      ATH_MSG_ERROR("Conversion didn't yield HepMC::GenEvent, aborting.");
      return StatusCode::FAILURE;
    }
    checkedEvent = checkEvent(std::move(hepmc_evts[0]), ctx);
  }
  else {
    // Get the event collection
    const McEventCollection* eventCollection = nullptr;
    StatusCode sc = evtStore()->retrieve(eventCollection, m_genEventKey);
    if (sc.isFailure() || eventCollection == 0) {
      ATH_MSG_ERROR("Unable to retrieve event collection from StoreGate with key " << m_genEventKey);
      return StatusCode::FAILURE;
    } else {
      ATH_MSG_DEBUG("Retrieved event collection from StoreGate with key " << m_genEventKey);
    }
 
    // Get the first event in the event collection
    const HepMC::GenEvent* event = eventCollection->front();
    if (event == nullptr) {
      ATH_MSG_ERROR("Rivet_i received a null HepMC event");
      return StatusCode::FAILURE;
    }
 
    // Modify the event units etc. if necessary
    checkedEvent = checkEvent(*event, ctx);
  }
 
  if(!checkedEvent) {
    ATH_MSG_ERROR("Check on HepMC event failed!");
    return StatusCode::FAILURE;
  }
 
  // Initialize Rivet (on the first event only)
  if (!m_init) {
    m_analysisHandler->init(*checkedEvent);
    m_init = true;
  }
 
  // Analyse the event
  m_analysisHandler->analyze(*checkedEvent);
 
  return StatusCode::SUCCESS;
}
 
 
StatusCode Rivet_i::finalize() {
  ATH_MSG_INFO("Rivet_i finalizing");
 
  // Setting cross-section in Rivet
  // If no user-specified cross-section available,
  // take whatever is in the GenEvent
  if (m_crossSection != 0)   m_analysisHandler->setCrossSection({m_crossSection, m_crossSection_uncert});
 
  // Call Rivet finalize
  m_analysisHandler->finalize();
 
 
 
  // Write out YODA file (add .yoda suffix if missing)
  if (m_file.find(".yoda") == std::string::npos) m_file += ".yoda.gz";
  auto pos = m_file.find(".gz.");
  if (pos == std::string::npos) {
    m_analysisHandler->writeData(m_file);
  }
  else {//filename is e.g. something.yoda.gz.1
      //write to output file name without the ".1"
      m_analysisHandler->writeData(m_file.substr(0, pos)+".gz");
      // then rename it as the requested output filename
      if (std::rename((m_file.substr(0, pos)+".gz").c_str(), m_file.c_str()) !=0) {
        std::string error_msg = "Impossible to rename ";
        error_msg += m_file.substr(0, pos)+".gz";
        error_msg += " as ";
        error_msg += m_file;
        ATH_MSG_ERROR(error_msg.c_str());
        return StatusCode::FAILURE;
    }
  }
 
  return StatusCode::SUCCESS;
}
 

bool cmpGenParticleByEDesc(HepMC::ConstGenParticlePtr a, HepMC::ConstGenParticlePtr b) {
  return a->momentum().e() > b->momentum().e();
}
 
inline std::vector<std::string> split(const std::string& input, const std::string& regex) {
  // passing -1 as the submatch index parameter performs splitting
  std::regex re(regex);
  std::sregex_token_iterator
  first{input.begin(), input.end(), re, -1},
    last;
    return {first, last};
}
 
std::unique_ptr<HepMC::GenEvent> Rivet_i::checkEvent(const HepMC::GenEvent& event, const EventContext& ctx) {
  auto modEvent = std::make_unique<HepMC::GenEvent>(event);
 
  if (!m_needsConversion) {
    // overwrite the HEPMC dummy event number with the proper ATLAS event number
    SG::ReadHandle<xAOD::EventInfo> evtInfo(m_evtInfoKey, ctx);
    modEvent->set_event_number(static_cast<int>(evtInfo->eventNumber()));
  }
 
  // weight-name cleaning
  std::shared_ptr<HepMC3::GenRunInfo> modRunInfo;
  if (event.run_info()) {
    modRunInfo = std::make_shared<HepMC3::GenRunInfo>(*(event.run_info().get()));
    if (event.run_info()->weight_names().empty() && event.weights().size() == 1) {
       modRunInfo->set_weight_names({"Default"});
    }
  }
  else {
    ATH_MSG_DEBUG("No run info, event weights size is " << event.weights().size() );
    modRunInfo = std::make_shared<HepMC3::GenRunInfo>();
    std::vector<std::string> w_names;
    for (size_t i = 0; i < event.weights().size(); i++) { w_names.push_back(std::string("badweight") + std::to_string(i)); }
    modRunInfo->set_weight_names(w_names);
  }
  modEvent->set_run_info(std::move(modRunInfo));
  std::vector<std::string>  w_names = modEvent->weight_names();
  if (w_names.size()) {
    std::vector<std::pair<std::string,std::string> > w_subs = {
      {" nominal ",""},
      {" set = ","_"},
      {" = ","_"},
      {"=",""},
      {",",""},
      {".",""},
      {":",""},
      {" ","_"},
      {"#","num"},
      {"\n","_"},
      {"/","over"}
    };
    for (std::string& wname : w_names) {
      for (const auto& sub : w_subs) {
        size_t start_pos = wname.find(sub.first);
        while (start_pos != std::string::npos) {
          wname.replace(start_pos, sub.first.length(), sub.second);
          start_pos = wname.find(sub.first);
        }
      }
    }
    modEvent->run_info()->set_weight_names(w_names);
  }
 
  modEvent->set_units(HepMC3::Units::GEV, HepMC3::Units::MM);
  if (modEvent->particles().size() == 1) modEvent->set_beam_particles(modEvent->particles().front(), modEvent->particles().front());
  if (m_patchBeams) {
    // workaround in case beam particles were missing in xAOD::Truth
    // first work out centre-of-mass energy
    double etotal = 0;
    for (const auto& p : modEvent->particles()) {
      if (!MC::isStable(p)) continue;
      etotal += p->momentum().e();
    }
    const double ebeam = 0.5*etotal;
    // create dummy beam particles
    HepMC::GenParticlePtr b1 = std::make_shared<HepMC::GenParticle>(HepMC::FourVector(0,0,ebeam,ebeam),2212,4);
    HepMC::GenParticlePtr b2 = std::make_shared<HepMC::GenParticle>(HepMC::FourVector(0,0,-1*ebeam,ebeam),2212,4);
    // remove particles incorrectly labelled as beam particles
    std::vector<HepMC::GenParticlePtr> notBeams;
    for (const HepMC::GenParticlePtr& p : modEvent->beams()) {
      if (!MC::isBeam(p))  notBeams.push_back(p);
    }
    //AV: the loop is over shared pointers! Should be const auto&
    for (const auto& bp : notBeams)  bp->production_vertex()->remove_particle_out(bp);
    // add dummy beam particles
    modEvent->set_beam_particles(std::move(b1), std::move(b2));
  }
  if (modEvent->beams().front()->momentum().e() > 50000.0) {
    MeV2GeV(*modEvent);
  }
 
  return modEvent;
}
 
void Rivet_i::MeV2GeV(HepMC::GenEvent& evt) {
  for (auto& p: evt.particles()) {
    p->set_momentum(p->momentum()*0.001);
    p->set_generated_mass(p->generated_mass()*0.001);
  }
}