| 1 | //----------------------------------------------------------------------
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| 2 | // This file distributed with FastJet has been obtained from
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| 3 | // http://www.pa.msu.edu/~huston/Les_Houches_2005/JetClu+Midpoint-StandAlone.tgz
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| 4 | //
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| 5 | // Permission to distribute it with FastJet has been granted by Joey
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| 6 | // Huston (see the COPYING file in the main FastJet directory for
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| 7 | // details).
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| 8 | // Changes from the original file are listed below.
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| 9 | //----------------------------------------------------------------------
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| 10 |
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| 11 | // History of changes compared to the original MidPointAlgorithm.cc file
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| 12 | //
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| 13 | // 2009-01-17 Gregory Soyez <soyez@fastjet.fr>
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| 14 | //
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| 15 | // * put the code in the fastjet::cdf namespace
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| 16 | //
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| 17 | // 2008-01-15 Gavin Salam <salam@lpthe.jussieu.fr>
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| 18 | //
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| 19 | // * put in the volatile fix for midpoint with optimization;
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| 20 | // checked regression test, and that speed comes out OK
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| 21 | //
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| 22 | //
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| 23 | // 2007-10-16 Gavin Salam <salam@lpthe.jussieu.fr>
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| 24 | //
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| 25 | // * added protection to midpoint for cases where no stable cones
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| 26 | // are found
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| 27 | //
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| 28 | // 2007-03-10 Gavin Salam <salam@lpthe.jussieu.fr>
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| 29 | //
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| 30 | // * added support for the pttilde scale choice in the CDF midpoint code
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| 31 | //
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| 32 | // 2007-02-21 Gavin Salam <salam@lpthe.jussieu.fr>
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| 33 | //
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| 34 | // * added option of choosing the scale used in the split-merge
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| 35 | // procedure (pt [default], Et or mt)
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| 36 | //
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| 37 | // 2006-09-24 Gavin Salam <salam@lpthe.jussieu.fr>
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| 38 | //
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| 39 | // * removed the local_sort method
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| 40 | //
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| 41 | // 2006-09-24 Gavin Salam <salam@lpthe.jussieu.fr>
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| 42 | //
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| 43 | // * added JetClu+MidPoint to FastJet
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| 44 |
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| 45 | #include "MidPointAlgorithm.hh"
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| 46 | #include "ClusterComparisons.hh"
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| 47 | #include <algorithm>
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| 48 | #include <iostream>
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| 49 | #include <cmath>
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| 50 |
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| 51 | #include <fastjet/internal/base.hh>
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| 52 |
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| 53 | FASTJET_BEGIN_NAMESPACE
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| 54 |
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| 55 | namespace cdf{
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| 56 |
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| 57 | void MidPointAlgorithm::findStableConesFromSeeds(std::vector<PhysicsTower>& towers, std::vector<Cluster>& stableCones)
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| 58 | {
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| 59 | bool reduceConeSize = true;
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| 60 | for(std::vector<PhysicsTower>::iterator towerIter = towers.begin(); towerIter != towers.end(); towerIter++)
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| 61 | if(towerIter->fourVector.pt() > _seedThreshold)
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| 62 | iterateCone(towerIter->fourVector.y(),towerIter->fourVector.phi(),0,towers,stableCones,reduceConeSize);
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| 63 | }
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| 64 |
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| 65 | void MidPointAlgorithm::findStableConesFromMidPoints(std::vector<PhysicsTower>& towers, std::vector<Cluster>& stableCones)
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| 66 | {
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| 67 | // distanceOK[i-1][j] = Is distance between stableCones i and j (i>j) less than 2*_coneRadius?
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| 68 | std::vector< std::vector<bool> > distanceOK;
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| 69 | distanceOK.resize(stableCones.size() - 1);
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| 70 | for(int nCluster1 = 1; nCluster1 < stableCones.size(); nCluster1++){
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| 71 | distanceOK[nCluster1 - 1].resize(nCluster1);
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| 72 | double cluster1Rapidity = stableCones[nCluster1].fourVector.y();
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| 73 | double cluster1Phi = stableCones[nCluster1].fourVector.phi();
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| 74 | for(int nCluster2 = 0; nCluster2 < nCluster1; nCluster2++){
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| 75 | double cluster2Rapidity = stableCones[nCluster2].fourVector.y();
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| 76 | double cluster2Phi = stableCones[nCluster2].fourVector.phi();
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| 77 | double dRapidity = fabs(cluster1Rapidity - cluster2Rapidity);
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| 78 | double dPhi = fabs(cluster1Phi - cluster2Phi);
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| 79 | if(dPhi > M_PI)
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| 80 | dPhi = 2*M_PI - dPhi;
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| 81 | double dR = sqrt(dRapidity*dRapidity + dPhi*dPhi);
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| 82 | distanceOK[nCluster1 - 1][nCluster2] = dR < 2*_coneRadius;
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| 83 | }
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| 84 | }
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| 85 |
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| 86 | // Find all pairs (triplets, ...) of stableCones which are less than 2*_coneRadius apart from each other.
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| 87 | std::vector< std::vector<int> > pairs(0);
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| 88 | std::vector<int> testPair(0);
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| 89 | int maxClustersInPair = _maxPairSize;
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| 90 | if(!maxClustersInPair)
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| 91 | maxClustersInPair = stableCones.size();
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| 92 | addClustersToPairs(testPair,pairs,distanceOK,maxClustersInPair);
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| 93 |
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| 94 | // Loop over all combinations. Calculate MidPoint. Make midPointClusters.
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| 95 | bool reduceConeSize = false;
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| 96 | for(int iPair = 0; iPair < pairs.size(); iPair++){
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| 97 | // Calculate rapidity, phi and pT of MidPoint.
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| 98 | LorentzVector midPoint(0,0,0,0);
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| 99 | for(int iPairMember = 0; iPairMember < pairs[iPair].size(); iPairMember++)
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| 100 | midPoint.add(stableCones[pairs[iPair][iPairMember]].fourVector);
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| 101 | iterateCone(midPoint.y(),midPoint.phi(),midPoint.pt(),towers,stableCones,reduceConeSize);
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| 102 | }
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| 103 |
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| 104 | //sort(stableCones.begin(),stableCones.end(),ClusterPtGreater());
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| 105 | local_sort(stableCones); // GPS mod. to allow split-merge with various scales
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| 106 | }
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| 107 |
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| 108 |
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| 109 | void MidPointAlgorithm::iterateCone(volatile double startRapidity, volatile double startPhi, volatile double startPt,
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| 110 | std::vector<PhysicsTower>& towers, std::vector<Cluster>& stableCones, bool reduceConeSize)
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| 111 | {
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| 112 | int nIterations = 0;
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| 113 | bool keepJet = true;
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| 114 | Cluster trialCone;
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| 115 | double iterationConeRadius = _coneRadius;
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| 116 | if(reduceConeSize)
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| 117 | iterationConeRadius *= sqrt(_coneAreaFraction);
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| 118 | while(nIterations++ < _maxIterations + 1 && keepJet){
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| 119 | trialCone.clear();
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| 120 | // Find particles which should go in the cone.
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| 121 | if(nIterations == _maxIterations + 1)
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| 122 | iterationConeRadius = _coneRadius;
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| 123 | for(std::vector<PhysicsTower>::iterator towerIter = towers.begin(); towerIter != towers.end(); towerIter++){
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| 124 | double dRapidity = fabs(towerIter->fourVector.y() - startRapidity);
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| 125 | double dPhi = fabs(towerIter->fourVector.phi() - startPhi);
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| 126 | if(dPhi > M_PI)
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| 127 | dPhi = 2*M_PI - dPhi;
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| 128 | double dR = sqrt(dRapidity*dRapidity + dPhi*dPhi);
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| 129 | if(dR < iterationConeRadius)
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| 130 | trialCone.addTower(*towerIter);
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| 131 | }
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| 132 | if(!trialCone.size()) // Empty cone?
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| 133 | keepJet = false;
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| 134 | else{
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| 135 | if(nIterations <= _maxIterations){
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| 136 | volatile double endRapidity = trialCone.fourVector.y();
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| 137 | volatile double endPhi = trialCone.fourVector.phi();
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| 138 | volatile double endPt = trialCone.fourVector.pt();
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| 139 | // Do we have a stable cone?
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| 140 | if(endRapidity == startRapidity && endPhi == startPhi && endPt == startPt){
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| 141 | // If cone size is reduced, then do one more iteration.
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| 142 | nIterations = _maxIterations;
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| 143 | if(!reduceConeSize)
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| 144 | nIterations++;
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| 145 | }
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| 146 | else{
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| 147 | // Another iteration.
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| 148 | startRapidity = endRapidity;
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| 149 | startPhi = endPhi;
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| 150 | startPt = endPt;
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| 151 | }
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| 152 | }
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| 153 | }
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| 154 | }
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| 155 |
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| 156 | if(keepJet){
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| 157 | // We have a stable cone.
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| 158 | bool identical = false;
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| 159 | for(std::vector<Cluster>::iterator stableConeIter = stableCones.begin(); stableConeIter != stableCones.end(); stableConeIter++)
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| 160 | if(trialCone.fourVector.isEqual(stableConeIter->fourVector))
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| 161 | identical = true;
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| 162 | if(!identical)
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| 163 | stableCones.push_back(trialCone);
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| 164 | }
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| 165 | }
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| 166 |
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| 167 | void MidPointAlgorithm::addClustersToPairs(std::vector<int>& testPair, std::vector< std::vector<int> >& pairs,
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| 168 | std::vector< std::vector<bool> >& distanceOK, int maxClustersInPair)
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| 169 | {
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| 170 | // Recursively adds clusters to pairs, triplets, ... whose mid-points are then calculated.
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| 171 |
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| 172 | // Find StableCone number to start with (either 0 at the beginning or last element of testPair + 1).
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| 173 | int nextClusterStart = 0;
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| 174 | if(testPair.size())
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| 175 | nextClusterStart = testPair.back() + 1;
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| 176 | for(int nextCluster = nextClusterStart; nextCluster <= distanceOK.size(); nextCluster++){
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| 177 | // Is new SeedCone less than 2*_coneRadius apart from all clusters in testPair?
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| 178 | bool addCluster = true;
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| 179 | for(int iCluster = 0; iCluster < testPair.size() && addCluster; iCluster++)
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| 180 | if(!distanceOK[nextCluster - 1][testPair[iCluster]])
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| 181 | addCluster = false;
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| 182 | if(addCluster){
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| 183 | // Add it to the testPair.
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| 184 | testPair.push_back(nextCluster);
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| 185 | // If testPair is a pair, add it to pairs.
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| 186 | if(testPair.size() > 1)
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| 187 | pairs.push_back(testPair);
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| 188 | // If not bigger than allowed, find more clusters within 2*_coneRadius.
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| 189 | if(testPair.size() < maxClustersInPair)
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| 190 | addClustersToPairs(testPair,pairs,distanceOK,maxClustersInPair);
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| 191 | // All combinations containing testPair found. Remove last element.
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| 192 | testPair.pop_back();
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| 193 | }
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| 194 | }
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| 195 | }
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| 196 |
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| 197 | void MidPointAlgorithm::splitAndMerge(std::vector<Cluster>& stableCones, std::vector<Cluster>& jets)
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| 198 | {
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| 199 | bool mergingNotFinished = true;
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| 200 | while(mergingNotFinished){
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| 201 | // Sort the stable cones (highest pt first).
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| 202 | //sort(stableCones.begin(),stableCones.end(),ClusterPtGreater());
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| 203 | local_sort(stableCones);
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| 204 |
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| 205 | // Start with the highest pt cone.
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| 206 | std::vector<Cluster>::iterator stableConeIter1 = stableCones.begin();
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| 207 | if(stableConeIter1 == stableCones.end()) // Stable cone list empty?
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| 208 | mergingNotFinished = false;
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| 209 | else{
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| 210 | bool coneNotModified = true;
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| 211 | // Determine whether highest pt cone has an overlap with other stable cones.
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| 212 | std::vector<Cluster>::iterator stableConeIter2 = stableConeIter1;
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| 213 | stableConeIter2++; // 2nd highest pt cone.
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| 214 | while(coneNotModified && stableConeIter2 != stableCones.end()){
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| 215 | // Calculate overlap of the two cones.
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| 216 | Cluster overlap;
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| 217 | for(std::vector<PhysicsTower>::iterator towerIter1 = stableConeIter1->towerList.begin();
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| 218 | towerIter1 != stableConeIter1->towerList.end();
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| 219 | towerIter1++){
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| 220 | bool isInCone2 = false;
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| 221 | for(std::vector<PhysicsTower>::iterator towerIter2 = stableConeIter2->towerList.begin();
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| 222 | towerIter2 != stableConeIter2->towerList.end();
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| 223 | towerIter2++)
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| 224 | if(towerIter1->isEqual(*towerIter2))
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| 225 | isInCone2 = true;
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| 226 | if(isInCone2)
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| 227 | overlap.addTower(*towerIter1);
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| 228 | }
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| 229 | if(overlap.size()){ // non-empty overlap
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| 230 | coneNotModified = false;
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| 231 | // GPS mod to allow various scale choices in split merge --------
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| 232 | double overlap_scale, jet2_scale;
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| 233 | switch(_smScale) {
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| 234 | case SM_pt:
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| 235 | overlap_scale = overlap.fourVector.pt();
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| 236 | jet2_scale = stableConeIter2->fourVector.pt();
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| 237 | break;
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| 238 | case SM_Et:
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| 239 | overlap_scale = overlap.fourVector.Et();
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| 240 | jet2_scale = stableConeIter2->fourVector.Et();
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| 241 | break;
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| 242 | case SM_mt:
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| 243 | overlap_scale = overlap.fourVector.mt();
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| 244 | jet2_scale = stableConeIter2->fourVector.mt();
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| 245 | break;
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| 246 | case SM_pttilde:
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| 247 | overlap_scale = overlap.pt_tilde;
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| 248 | jet2_scale = stableConeIter2->pt_tilde;
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| 249 | break;
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| 250 | default:
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| 251 | std::cerr << "Unrecognized value for _smScale: "
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| 252 | << _smScale << std::endl;
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| 253 | exit(-1);
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| 254 | }
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| 255 | if(overlap_scale >= _overlapThreshold*jet2_scale){
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| 256 | // end of GPS modification ---------------------------
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| 257 | //if(overlap.fourVector.pt() >= _overlapThreshold*stableConeIter2->fourVector.pt()){
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| 258 | // Merge the two cones.
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| 259 | for(std::vector<PhysicsTower>::iterator towerIter2 = stableConeIter2->towerList.begin();
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| 260 | towerIter2 != stableConeIter2->towerList.end();
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| 261 | towerIter2++){
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| 262 | bool isInOverlap = false;
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| 263 | for(std::vector<PhysicsTower>::iterator overlapTowerIter = overlap.towerList.begin();
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| 264 | overlapTowerIter != overlap.towerList.end();
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| 265 | overlapTowerIter++)
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| 266 | if(towerIter2->isEqual(*overlapTowerIter))
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| 267 | isInOverlap = true;
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| 268 | if(!isInOverlap)
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| 269 | stableConeIter1->addTower(*towerIter2);
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| 270 | }
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| 271 | // Remove the second cone.
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| 272 | stableCones.erase(stableConeIter2);
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| 273 | }
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| 274 | else{
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| 275 | // Separate the two cones.
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| 276 | // Which particle goes where?
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| 277 | std::vector<PhysicsTower> removeFromCone1,removeFromCone2;
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| 278 | for(std::vector<PhysicsTower>::iterator towerIter = overlap.towerList.begin();
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| 279 | towerIter != overlap.towerList.end();
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| 280 | towerIter++){
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| 281 | double towerRapidity = towerIter->fourVector.y();
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| 282 | double towerPhi = towerIter->fourVector.phi();
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| 283 | // Calculate distance from cone 1.
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| 284 | double dRapidity1 = fabs(towerRapidity - stableConeIter1->fourVector.y());
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| 285 | double dPhi1 = fabs(towerPhi - stableConeIter1->fourVector.phi());
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| 286 | if(dPhi1 > M_PI)
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| 287 | dPhi1 = 2*M_PI - dPhi1;
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| 288 | double dRJet1 = sqrt(dRapidity1*dRapidity1 + dPhi1*dPhi1);
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| 289 | // Calculate distance from cone 2.
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| 290 | double dRapidity2 = fabs(towerRapidity - stableConeIter2->fourVector.y());
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| 291 | double dPhi2 = fabs(towerPhi - stableConeIter2->fourVector.phi());
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| 292 | if(dPhi2 > M_PI)
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| 293 | dPhi2 = 2*M_PI - dPhi2;
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| 294 | double dRJet2 = sqrt(dRapidity2*dRapidity2 + dPhi2*dPhi2);
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| 295 | if(dRJet1 < dRJet2)
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| 296 | // Particle is closer to cone 1. To be removed from cone 2.
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| 297 | removeFromCone2.push_back(*towerIter);
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| 298 | else
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| 299 | // Particle is closer to cone 2. To be removed from cone 1.
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| 300 | removeFromCone1.push_back(*towerIter);
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| 301 | }
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| 302 | // Remove particles in the overlap region from the cones to which they have the larger distance.
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| 303 | for(std::vector<PhysicsTower>::iterator towerIter = removeFromCone1.begin();
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| 304 | towerIter != removeFromCone1.end();
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| 305 | towerIter++)
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| 306 | stableConeIter1->removeTower(*towerIter);
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| 307 | for(std::vector<PhysicsTower>::iterator towerIter = removeFromCone2.begin();
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| 308 | towerIter != removeFromCone2.end();
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| 309 | towerIter++)
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| 310 | stableConeIter2->removeTower(*towerIter);
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| 311 | }
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| 312 | }
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| 313 | stableConeIter2++;
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| 314 | }
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| 315 | if(coneNotModified){
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| 316 | // Cone 1 has no overlap with any of the other cones and can become a jet.
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| 317 | jets.push_back(*stableConeIter1);
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| 318 | stableCones.erase(stableConeIter1);
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| 319 | }
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| 320 | }
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| 321 | }
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| 322 |
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| 323 | //sort(jets.begin(),jets.end(),ClusterPtGreater());
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| 324 | local_sort(jets); // GPS mod. to allow split-merge with various scales
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| 325 | }
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| 326 |
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| 327 |
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| 328 |
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| 329 | void MidPointAlgorithm::local_sort(std::vector<Cluster>& clusters) {
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| 330 | switch(_smScale) {
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| 331 | case SM_pt:
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| 332 | sort(clusters.begin(),clusters.end(),ClusterPtGreater());
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| 333 | break;
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| 334 | case SM_Et:
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| 335 | sort(clusters.begin(),clusters.end(),ClusterFourVectorEtGreater());
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| 336 | break;
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| 337 | case SM_mt:
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| 338 | sort(clusters.begin(),clusters.end(),ClusterMtGreater());
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| 339 | break;
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| 340 | case SM_pttilde:
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| 341 | sort(clusters.begin(),clusters.end(),ClusterPtTildeGreater());
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| 342 | break;
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| 343 | default:
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| 344 | std::cerr << "Unrecognized value for _smScale: " << _smScale << std::endl;
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| 345 | exit(-1);
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| 346 | }
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| 347 | }
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| 348 |
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| 349 |
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| 350 |
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| 351 | void MidPointAlgorithm::run(std::vector<PhysicsTower>& towers, std::vector<Cluster>& jets)
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| 352 | {
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| 353 | std::vector<Cluster> stableCones;
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| 354 | findStableConesFromSeeds(towers,stableCones);
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| 355 | // GPS addition to prevent crashes if no stable cones
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| 356 | // are found (e.g. all particles below seed threshold)
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| 357 | if (stableCones.size() > 0) {
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| 358 | findStableConesFromMidPoints(towers,stableCones);
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| 359 | splitAndMerge(stableCones,jets);
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| 360 | }
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| 361 | }
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| 362 |
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| 363 | } // namespace cdf
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| 364 |
|
|---|
| 365 | FASTJET_END_NAMESPACE
|
|---|
