PVSorterBySumP.cc

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// Includes
#include "DataFormats/VertexReco/interface/Vertex.h"
#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 <memory>
#include <vector>
#include <sstream>


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

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

private:
  edm::EDGetTokenT<std::vector<reco::Vertex>> src_;
};


// construction

//______________________________________________________________________________
bestPVselector::bestPVselector(edm::ParameterSet const& iConfig)
  : src_{consumes<std::vector<reco::Vertex>>(iConfig.getParameter<edm::InputTag>("src"))}
{
  produces<std::vector<reco::Vertex>>();
}

// implementation of member functions

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

  auto theBestPV = std::make_unique<std::vector<reco::Vertex>>();

  if (!vertices->empty()) {
    auto sumSquarePt = [](auto const& pv) { return pv.p4().pt()*pv.p4().pt(); };
    auto bestPV = std::max_element(std::cbegin(*vertices), std::cend(*vertices),
                                   [sumSquarePt](auto const& v1, auto const& v2) {
                                     return sumSquarePt(v1) < sumSquarePt(v2);
                                   });
    theBestPV->push_back(*bestPV);
  }
  iEvent.put(std::move(theBestPV));
}

using HighestSumP4PrimaryVertexSelector = bestPVselector;
DEFINE_FWK_MODULE(HighestSumP4PrimaryVertexSelector);