Inheritance diagram for CandViewRefRandomSelector:

Public Member Functions
	CandViewRefRandomSelector (const edm::ParameterSet &pset)
bool	filter (edm::Event &, const edm::EventSetup &)
Private Attributes
unsigned int	choose_
bool	filter_
TRandom3	randy_
unsigned int	seed_
edm::InputTag	src_

Detailed Description

Definition at line 25 of file CandViewRefRandomSelector.cc.

Constructor & Destructor Documentation

CandViewRefRandomSelector::CandViewRefRandomSelector ( const edm::ParameterSet & pset ) [explicit]

Definition at line 37 of file CandViewRefRandomSelector.cc.

References choose_, edm::ParameterSet::exists(), filter_, edm::ParameterSet::getParameter(), randy_, seed_, and src_.

                                 {
  src_ = pset.getParameter<edm::InputTag>("src");
  choose_ = pset.getParameter<unsigned int>("choose");
  filter_ = pset.getParameter<bool>("filter");
  seed_ = pset.exists("seed") ? pset.getParameter<unsigned int>("seed") : 123;
  randy_ = TRandom3(seed_);
  produces<reco::CandidateBaseRefVector>();
}

Member Function Documentation

bool CandViewRefRandomSelector::filter	(	edm::Event &	evt,
		const edm::EventSetup &	es
	)		`[virtual]`

Implements edm::EDFilter.

Definition at line 47 of file CandViewRefRandomSelector.cc.

References choose_, filter_, edm::Event::getByLabel(), i, convertSQLitetoXML_cfg::output, edm::RefToBaseVector< T >::push_back(), edm::Event::put(), randy_, edm::RefToBaseVector< T >::size(), and src_.

                                                                {
  edm::Handle<edm::View<reco::Candidate> > cands;
  evt.getByLabel(src_, cands);
  std::auto_ptr<reco::CandidateBaseRefVector> output(
      new reco::CandidateBaseRefVector(cands));
  // If we don't have enough elements to select, just copy what we have
  const reco::CandidateBaseRefVector &inputRefs = cands->refVector();
  if (inputRefs.size() <= choose_) {
    *output = inputRefs;
  } else {
    for (size_t i = 0; i < inputRefs.size() && output->size() < choose_; ++i) {
      // based on https://stackoverflow.com/questions/48087/
      // select-a-random-n-elements-from-listt-in-c/48089#48089
      double selectionProb =
          (choose_ - output->size())*1.0/(inputRefs.size() - i);
      // throw a number to see if we select this element
      if (randy_.Rndm() < selectionProb)
        output->push_back(inputRefs[i]);
    }
  }
  size_t outputSize = output->size();
  evt.put(output);
  return ( !filter_ || outputSize );
}