PatVertexAnalyzer.cc

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#include <iostream>
#include <cmath>
#include <vector>
#include <string>

#include <TH1.h>
#include <TProfile.h>

#include "FWCore/Framework/interface/Frameworkfwd.h"
#include "FWCore/Framework/interface/Event.h"
#include "FWCore/Framework/interface/EventSetup.h"
#include "FWCore/Framework/interface/one/EDAnalyzer.h"
#include "FWCore/Utilities/interface/InputTag.h"
#include "FWCore/ParameterSet/interface/ParameterSet.h"
#include "FWCore/ServiceRegistry/interface/Service.h"

#include "CommonTools/UtilAlgos/interface/TFileService.h"

#include "DataFormats/BeamSpot/interface/BeamSpot.h"
#include "DataFormats/TrackReco/interface/Track.h"
#include "DataFormats/VertexReco/interface/Vertex.h"
#include "DataFormats/VertexReco/interface/VertexFwd.h"
#include "DataFormats/HepMCCandidate/interface/GenParticle.h"
#include "DataFormats/HepMCCandidate/interface/GenParticleFwd.h"

class PatVertexAnalyzer : public edm::one::EDAnalyzer<edm::one::SharedResources> {
public:
  PatVertexAnalyzer(const edm::ParameterSet &params);
  ~PatVertexAnalyzer() override;

  // virtual methods called from base class EDAnalyzer
  void beginJob() override;
  void analyze(const edm::Event &event, const edm::EventSetup &es) override;

private:
  // configuration parameters
  edm::EDGetTokenT<reco::VertexCollection> srcToken_;
  edm::EDGetTokenT<reco::GenParticleCollection> genParticlesToken_;

  TH1 *nVertices_, *nTracks_;
  TH1 *x_, *y_, *z_;
  TH1 *xErr_, *yErr_, *zErr_;
  TH1 *xDelta_, *yDelta_, *zDelta_;
  TH1 *xPull_, *yPull_, *zPull_;
};

PatVertexAnalyzer::PatVertexAnalyzer(const edm::ParameterSet &params)
    : srcToken_(consumes<reco::VertexCollection>(params.getParameter<edm::InputTag>("src"))),
      genParticlesToken_(consumes<reco::GenParticleCollection>(params.getParameter<edm::InputTag>("mc"))) {
  usesResource(TFileService::kSharedResource);
}

PatVertexAnalyzer::~PatVertexAnalyzer() {}

void PatVertexAnalyzer::beginJob() {
  // retrieve handle to auxiliary service
  //  used for storing histograms into ROOT file
  edm::Service<TFileService> fs;

  nVertices_ = fs->make<TH1F>("nVertices", "number of reconstructed primary vertices", 50, 0, 50);
  nTracks_ = fs->make<TH1F>("nTracks", "number of tracks at primary vertex", 100, 0, 300);
  x_ = fs->make<TH1F>("pvX", "primary vertex x", 100, -0.1, 0.1);
  y_ = fs->make<TH1F>("pvY", "primary vertex y", 100, -0.1, 0.1);
  z_ = fs->make<TH1F>("pvZ", "primary vertex z", 100, -30, 30);
  xErr_ = fs->make<TH1F>("pvErrorX", "primary vertex x error", 100, 0, 0.005);
  yErr_ = fs->make<TH1F>("pvErrorY", "primary vertex y error", 100, 0, 0.005);
  zErr_ = fs->make<TH1F>("pvErrorZ", "primary vertex z error", 100, 0, 0.01);
  xDelta_ = fs->make<TH1F>("pvDeltaX", "x shift wrt simulated vertex", 100, -0.01, 0.01);
  yDelta_ = fs->make<TH1F>("pvDeltaY", "y shift wrt simulated vertex", 100, -0.01, 0.01);
  zDelta_ = fs->make<TH1F>("pvDeltaZ", "z shift wrt simulated vertex", 100, -0.02, 0.02);
  xPull_ = fs->make<TH1F>("pvPullX", "primary vertex x pull", 100, -5, 5);
  yPull_ = fs->make<TH1F>("pvPullY", "primary vertex y pull", 100, -5, 5);
  zPull_ = fs->make<TH1F>("pvPullZ", "primary vertex z pull", 100, -5, 5);
}

void PatVertexAnalyzer::analyze(const edm::Event &event, const edm::EventSetup &es) {
  // handle to the primary vertex collection
  edm::Handle<reco::VertexCollection> pvHandle;
  event.getByToken(srcToken_, pvHandle);

  // handle to the generator particles (i.e. the MC truth)
  edm::Handle<reco::GenParticleCollection> genParticlesHandle;
  event.getByToken(genParticlesToken_, genParticlesHandle);

  // extract the position of the simulated vertex
  math::XYZPoint simPV = (*genParticlesHandle)[2].vertex();

  // the number of reconstructed primary vertices
  nVertices_->Fill(pvHandle->size());

  // if we have at least one, use the first (highest pt^2 sum)
  if (!pvHandle->empty()) {
    const reco::Vertex &pv = (*pvHandle)[0];

    nTracks_->Fill(pv.tracksSize());

    x_->Fill(pv.x());
    y_->Fill(pv.y());
    z_->Fill(pv.z());

    xErr_->Fill(pv.xError());
    yErr_->Fill(pv.yError());
    zErr_->Fill(pv.zError());

    xDelta_->Fill(pv.x() - simPV.X());
    yDelta_->Fill(pv.y() - simPV.Y());
    zDelta_->Fill(pv.z() - simPV.Z());

    xPull_->Fill((pv.x() - simPV.X()) / pv.xError());
    yPull_->Fill((pv.y() - simPV.Y()) / pv.yError());
    zPull_->Fill((pv.z() - simPV.Z()) / pv.zError());

    // we could access the tracks using the
    // pv.tracks_begin() ... pv.tracks_end() iterators
  }
}

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

DEFINE_FWK_MODULE(PatVertexAnalyzer);