ElectronFromPVSelector.cc

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// Includes
#include "FWCore/Framework/interface/Event.h"
#include "FWCore/Framework/interface/MakerMacros.h"
#include "FWCore/Framework/interface/global/EDProducer.h"
#include "FWCore/ParameterSet/interface/ParameterSet.h"
#include "FWCore/Utilities/interface/InputTag.h"

#include "CommonTools/Utils/interface/StringCutObjectSelector.h"

#include "DataFormats/EgammaCandidates/interface/GsfElectron.h"
#include "DataFormats/EgammaCandidates/interface/GsfElectronFwd.h"
#include "DataFormats/GsfTrackReco/interface/GsfTrack.h"
#include "DataFormats/GsfTrackReco/interface/GsfTrackExtra.h"
#include "DataFormats/GsfTrackReco/interface/GsfTrackExtraFwd.h"
#include "DataFormats/GsfTrackReco/interface/GsfTrackFwd.h"
#include "DataFormats/VertexReco/interface/Vertex.h"
#include "DataFormats/VertexReco/interface/VertexFwd.h"

#include <algorithm>
#include <cmath>
#include <memory>
#include <vector>


// class definition
class GsfElectronFromPVSelector : public edm::global::EDProducer<> {
public:

  explicit GsfElectronFromPVSelector(edm::ParameterSet const&);
  void produce(edm::StreamID, edm::Event&, edm::EventSetup const&) const override;

private:
  double max_dxy_;
  double max_dz_;
  edm::EDGetTokenT<std::vector<reco::Vertex>> v_recoVertexToken_;
  edm::EDGetTokenT<std::vector<reco::GsfElectron>> v_recoGsfElectronToken_;
};


// construction

GsfElectronFromPVSelector::GsfElectronFromPVSelector(edm::ParameterSet const& iConfig)
  : max_dxy_{iConfig.getParameter<double>("max_dxy")}
  , max_dz_{iConfig.getParameter<double>("max_dz")}
  , v_recoVertexToken_{consumes<std::vector<reco::Vertex>>(iConfig.getParameter<edm::InputTag>("srcVertex"))}
  , v_recoGsfElectronToken_{consumes<std::vector<reco::GsfElectron>>(iConfig.getParameter<edm::InputTag>("srcElectron"))}
{
  produces<std::vector<reco::GsfElectron>>();
}

// implementation of member functions

void GsfElectronFromPVSelector::produce(edm::StreamID, edm::Event& iEvent, edm::EventSetup const&) const
{
  edm::Handle<std::vector<reco::Vertex>> vertices;
  iEvent.getByToken(v_recoVertexToken_, vertices);

  edm::Handle<std::vector<reco::GsfElectron>> gsfElectrons;
  iEvent.getByToken(v_recoGsfElectronToken_, gsfElectrons);

  auto goodGsfElectrons = std::make_unique<std::vector<reco::GsfElectron>>();

  if (!vertices->empty() && !gsfElectrons->empty()) {
    auto const& pv = vertices->front();
    std::copy_if(std::cbegin(*gsfElectrons), std::cend(*gsfElectrons), std::back_inserter(*goodGsfElectrons),
                 [this, &pv](auto const& GsfElectron) {
                   return std::abs(GsfElectron.gsfTrack()->dxy(pv.position())) < max_dxy_ &&
                          std::abs(GsfElectron.gsfTrack()->dz(pv.position()))  < max_dz_;
                 });
  }

  iEvent.put(std::move(goodGsfElectrons));
}

DEFINE_FWK_MODULE(GsfElectronFromPVSelector);