ParticleDecayDrawer.cc

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/* class ParticleDecayDrawer
 *
 * \author Luca Lista, INFN
 */
#include "FWCore/Framework/interface/EDAnalyzer.h"
#include "FWCore/Utilities/interface/InputTag.h"
#include "FWCore/Framework/interface/ESHandle.h"
#include "SimGeneral/HepPDTRecord/interface/ParticleDataTable.h"
#include "DataFormats/Common/interface/View.h"
#include "DataFormats/Candidate/interface/Candidate.h"

class ParticleDecayDrawer : public edm::EDAnalyzer {
public:
  ParticleDecayDrawer(const edm::ParameterSet &);

private:
  void analyze(const edm::Event &, const edm::EventSetup &) override;
  edm::EDGetTokenT<edm::View<reco::Candidate> > srcToken_;
  std::string decay(const reco::Candidate &, std::list<const reco::Candidate *> &) const;
  edm::ESHandle<ParticleDataTable> pdt_;
  bool printP4_, printPtEtaPhi_, printVertex_;
  std::string printP4(const reco::Candidate &) const;
  bool accept(const reco::Candidate &, const std::list<const reco::Candidate *> &) const;
  bool select(const reco::Candidate &) const;
  bool hasValidDaughters(const reco::Candidate &) const;
};

#include "FWCore/ParameterSet/interface/ParameterSet.h"
#include "FWCore/Framework/interface/Event.h"
#include "DataFormats/Common/interface/Handle.h"
#include "FWCore/Framework/interface/EventSetup.h"
#include "FWCore/Utilities/interface/EDMException.h"
#include <iostream>
#include <sstream>
#include <algorithm>
using namespace std;
using namespace edm;
using namespace reco;

ParticleDecayDrawer::ParticleDecayDrawer(const ParameterSet &cfg)
    : srcToken_(consumes<edm::View<reco::Candidate> >(cfg.getParameter<InputTag>("src"))),
      printP4_(cfg.getUntrackedParameter<bool>("printP4", false)),
      printPtEtaPhi_(cfg.getUntrackedParameter<bool>("printPtEtaPhi", false)),
      printVertex_(cfg.getUntrackedParameter<bool>("printVertex", false)) {}

bool ParticleDecayDrawer::accept(const reco::Candidate &c, const list<const Candidate *> &skip) const {
  if (find(skip.begin(), skip.end(), &c) != skip.end())
    return false;
  return select(c);
}

bool ParticleDecayDrawer::select(const reco::Candidate &c) const { return c.status() == 3; }

bool ParticleDecayDrawer::hasValidDaughters(const reco::Candidate &c) const {
  size_t ndau = c.numberOfDaughters();
  for (size_t i = 0; i < ndau; ++i)
    if (select(*c.daughter(i)))
      return true;
  return false;
}

void ParticleDecayDrawer::analyze(const Event &event, const EventSetup &es) {
  es.getData(pdt_);
  Handle<View<Candidate> > particles;
  event.getByToken(srcToken_, particles);
  list<const Candidate *> skip;
  vector<const Candidate *> nodes, moms;
  for (View<Candidate>::const_iterator p = particles->begin(); p != particles->end(); ++p) {
    if (p->numberOfMothers() > 1) {
      if (select(*p)) {
        skip.push_back(&*p);
        nodes.push_back(&*p);
        for (size_t j = 0; j < p->numberOfMothers(); ++j) {
          const Candidate *mom = p->mother(j);
          const Candidate *grandMom;
          while ((grandMom = mom->mother()) != nullptr)
            mom = grandMom;
          if (select(*mom)) {
            moms.push_back(mom);
          }
        }
      }
    }
  }
  cout << "-- decay: --" << endl;
  if (!moms.empty()) {
    if (moms.size() > 1)
      for (size_t m = 0; m < moms.size(); ++m) {
        string dec = decay(*moms[m], skip);
        if (!dec.empty())
          cout << "{ " << dec << " } ";
      }
    else
      cout << decay(*moms[0], skip);
  }
  if (!nodes.empty()) {
    cout << "-> ";
    if (nodes.size() > 1) {
      for (size_t n = 0; n < nodes.size(); ++n) {
        skip.remove(nodes[n]);
        string dec = decay(*nodes[n], skip);
        if (!dec.empty()) {
          if (dec.find("->", 0) != string::npos)
            cout << " ( " << dec << " )";
          else
            cout << " " << dec;
        }
      }
    } else {
      skip.remove(nodes[0]);
      cout << decay(*nodes[0], skip);
    }
  }
  cout << endl;
}

string ParticleDecayDrawer::printP4(const Candidate &c) const {
  ostringstream cout;
  if (printP4_)
    cout << " (" << c.px() << ", " << c.py() << ", " << c.pz() << "; " << c.energy() << ")";
  if (printPtEtaPhi_)
    cout << " [" << c.pt() << ": " << c.eta() << ", " << c.phi() << "]";
  if (printVertex_)
    cout << " {" << c.vx() << ", " << c.vy() << ", " << c.vz() << "}";
  return cout.str();
}

string ParticleDecayDrawer::decay(const Candidate &c, list<const Candidate *> &skip) const {
  string out;
  if (find(skip.begin(), skip.end(), &c) != skip.end())
    return out;
  skip.push_back(&c);

  int id = c.pdgId();
  const ParticleData *pd = pdt_->particle(id);
  assert(pd != nullptr);
  out += (pd->name() + printP4(c));

  size_t validDau = 0, ndau = c.numberOfDaughters();
  for (size_t i = 0; i < ndau; ++i)
    if (accept(*c.daughter(i), skip))
      ++validDau;
  if (validDau == 0)
    return out;

  out += " ->";

  for (size_t i = 0; i < ndau; ++i) {
    const Candidate *d = c.daughter(i);
    if (accept(*d, skip)) {
      string dec = decay(*d, skip);
      if (dec.find("->", 0) != string::npos)
        out += (" ( " + dec + " )");
      else
        out += (" " + dec);
    }
  }
  return out;
}

#include "FWCore/Framework/interface/MakerMacros.h"

DEFINE_FWK_MODULE(ParticleDecayDrawer);