Sorting a vector based on another vector: http://stackoverflow.com/questions/236172/how-do-i-sort-a-stdvector-by-the-values-of-a-different-stdvector
struct tlvordering { bool operator ()(std::pair<size_t, std::vector<TLorentzVector>::const_iterator> const& a, std::pair<size_t, std::vector<TLorentzVector>::const_iterator> const& b) { return (*(a.second)).Pt() > (b.second->Pt()); } }; template <typename T> std::vector<T> sort_from_tlvref( std::vector<T> const& in, std::vector<std::pair<size_t, std::vector<TLorentzVector>::const_iterator> > const& reference ) { std::vector<T> ret(in.size()); size_t const size = in.size(); for (size_t i = 0; i < size; ++i) ret[i] = in[reference[i].first]; return ret; } void sortJetsByPt(std::vector<unsigned int>& selJets, // index vector std::vector<TLorentzVector>& selJetsP4, std::vector<int>& selJetsSVMassBins, std::vector<double>& selJetsSVMassSum, std::vector< std::vector<bool> >& selJetsBTags, std::vector<JetFlavor::Code>& selJetsFlav) { // make a pair of index order and TLorentzVector std::vector<std::pair<size_t, std::vector<TLorentzVector>::const_iterator> > order(selJetsP4.size()); size_t n = 0; for (std::vector<TLorentzVector>::const_iterator it = selJetsP4.begin(); it != selJetsP4.end(); ++it, ++n) { order[n] = std::make_pair(n, it); } // sort order pair by jet Pt sort(order.begin(), order.end(), tlvordering()); // user order pair as reference for sorting all vectors selJets = sort_from_tlvref(selJets, order); selJetsP4 = sort_from_tlvref(selJetsP4, order); selJetsSVMassBins = sort_from_tlvref(selJetsSVMassBins, order); selJetsSVMassSum = sort_from_tlvref(selJetsSVMassSum, order); selJetsBTags = sort_from_tlvref(selJetsBTags, order); selJetsFlav = sort_from_tlvref(selJetsFlav, order); // loop over jets and change order // for (size_t iJ = 0; iJ < selJets.size()-1; ++iJ) { // // if (selJetsP4[iJ].Pt() < selJetsP4[iJ+1].Pt()) { // jetOrder[iJ] = iJ+1 // } // } }