UtilAlgos/interface/SortCollectionSelector.h

0001 #ifndef RecoAlgos_SortCollectionSelector_h
0002 #define RecoAlgos_SortCollectionSelector_h
0003 /** \class SortCollectionSelector
0004  *
0005  * selects the first N elements based on a sorting algorithm
0006  *
0007  * \author Luca Lista, INFN
0008  *
0009  * \version $Revision: 1.1 $
0010  *
0011  * $Id: SortCollectionSelector.h,v 1.1 2009/03/03 13:07:28 llista Exp $
0012  *
0013  */
0014
0015 #include "FWCore/Framework/interface/ConsumesCollector.h"
0016 #include "FWCore/ParameterSet/interface/ParameterSet.h"
0017 #include "FWCore/ParameterSet/interface/ParameterSetDescription.h"
0018 #include "CommonTools/UtilAlgos/interface/SelectionAdderTrait.h"
0019 #include "CommonTools/UtilAlgos/interface/StoreContainerTrait.h"
0020 #include "CommonTools/UtilAlgos/interface/ParameterAdapter.h"
0021 #include "CommonTools/UtilAlgos/interface/SelectedOutputCollectionTrait.h"
0022 #include <algorithm>
0023 #include <utility>
0024
0025 namespace edm {
0026   class Event;
0027   class EventSetup;
0028 }  // namespace edm
0029
0030 template <typename InputCollection,
0031           typename Comparator,
0032           typename OutputCollection = typename helper::SelectedOutputCollectionTrait<InputCollection>::type,
0033           typename StoreContainer = typename helper::StoreContainerTrait<OutputCollection>::type,
0034           typename RefAdder = typename helper::SelectionAdderTrait<InputCollection, StoreContainer>::type>
0035 class SortCollectionSelector {
0036 public:
0037   typedef InputCollection collection;
0038
0039 private:
0040   typedef const typename InputCollection::value_type *reference;
0041   typedef std::pair<reference, size_t> pair;
0042   typedef StoreContainer container;
0043   typedef typename container::const_iterator const_iterator;
0044
0045 public:
0046   SortCollectionSelector(const edm::ParameterSet &cfg, edm::ConsumesCollector &&iC)
0047       : compare_(Comparator()), maxNumber_(cfg.template getParameter<unsigned int>("maxNumber")) {}
0048   const_iterator begin() const { return selected_.begin(); }
0049   const_iterator end() const { return selected_.end(); }
0050   void select(const edm::Handle<InputCollection> &c, const edm::Event &, const edm::EventSetup &) {
0051     std::vector<pair> v;
0052     for (size_t idx = 0; idx < c->size(); ++idx)
0053       v.push_back(std::make_pair(&(*c)[idx], idx));
0054     std::sort(v.begin(), v.end(), compare_);
0055     selected_.clear();
0056     for (size_t i = 0; i < maxNumber_ && i < v.size(); ++i)
0057       addRef_(selected_, c, v[i].second);
0058   }
0059
0060   static void fillPSetDescription(edm::ParameterSetDescription &desc) { desc.add<unsigned int>("maxNumber", 1); }
0061
0062 private:
0063   struct PairComparator {
0064     PairComparator(const Comparator &cmp) : cmp_(cmp) {}
0065     bool operator()(const pair &t1, const pair &t2) const { return cmp_(*t1.first, *t2.first); }
0066     Comparator cmp_;
0067   };
0068   PairComparator compare_;
0069   unsigned int maxNumber_;
0070   StoreContainer selected_;
0071   RefAdder addRef_;
0072 };
0073
0074 #endif