Basic2DGenericPFlowClusterizer.cc

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#include "Basic2DGenericPFlowClusterizer.h"
#include "DataFormats/ParticleFlowReco/interface/PFRecHit.h"
#include "FWCore/MessageLogger/interface/MessageLogger.h"
#include "DataFormats/Math/interface/deltaR.h"
 
#include "Math/GenVector/VectorUtil.h"
 
#include "vdt/vdtMath.h"
 
#include <iterator>
 
#ifdef PFLOW_DEBUG
#define LOGVERB(x) edm::LogVerbatim(x)
#define LOGWARN(x) edm::LogWarning(x)
#define LOGERR(x) edm::LogError(x)
#define LOGDRESSED(x) edm::LogInfo(x)
#else
#define LOGVERB(x) LogTrace(x)
#define LOGWARN(x) edm::LogWarning(x)
#define LOGERR(x) edm::LogError(x)
#define LOGDRESSED(x) LogDebug(x)
#endif
 
Basic2DGenericPFlowClusterizer::Basic2DGenericPFlowClusterizer(const edm::ParameterSet& conf)
    : PFClusterBuilderBase(conf),
      _maxIterations(conf.getParameter<unsigned>("maxIterations")),
      _stoppingTolerance(conf.getParameter<double>("stoppingTolerance")),
      _showerSigma2(std::pow(conf.getParameter<double>("showerSigma"), 2.0)),
      _excludeOtherSeeds(conf.getParameter<bool>("excludeOtherSeeds")),
      _minFracTot(conf.getParameter<double>("minFracTot")),
      _layerMap({{"PS2", (int)PFLayer::PS2},
                 {"PS1", (int)PFLayer::PS1},
                 {"ECAL_ENDCAP", (int)PFLayer::ECAL_ENDCAP},
                 {"ECAL_BARREL", (int)PFLayer::ECAL_BARREL},
                 {"NONE", (int)PFLayer::NONE},
                 {"HCAL_BARREL1", (int)PFLayer::HCAL_BARREL1},
                 {"HCAL_BARREL2_RING0", (int)PFLayer::HCAL_BARREL2},
                 {"HCAL_BARREL2_RING1", 100 * (int)PFLayer::HCAL_BARREL2},
                 {"HCAL_ENDCAP", (int)PFLayer::HCAL_ENDCAP},
                 {"HF_EM", (int)PFLayer::HF_EM},
                 {"HF_HAD", (int)PFLayer::HF_HAD}}) {
  const std::vector<edm::ParameterSet>& thresholds = conf.getParameterSetVector("recHitEnergyNorms");
  for (const auto& pset : thresholds) {
    const std::string& det = pset.getParameter<std::string>("detector");
 
    std::vector<int> depths;
    std::vector<double> rhE_norm;
 
    if (det == std::string("HCAL_BARREL1") || det == std::string("HCAL_ENDCAP")) {
      depths = pset.getParameter<std::vector<int> >("depths");
      rhE_norm = pset.getParameter<std::vector<double> >("recHitEnergyNorm");
    } else {
      depths.push_back(0);
      rhE_norm.push_back(pset.getParameter<double>("recHitEnergyNorm"));
    }
 
    if (rhE_norm.size() != depths.size()) {
      throw cms::Exception("InvalidPFRecHitThreshold")
          << "PFlowClusterizerThreshold mismatch with the numbers of depths";
    }
 
    auto entry = _layerMap.find(det);
    if (entry == _layerMap.end()) {
      throw cms::Exception("InvalidDetectorLayer") << "Detector layer : " << det << " is not in the list of recognized"
                                                   << " detector layers!";
    }
    _recHitEnergyNorms.emplace(_layerMap.find(det)->second, std::make_pair(depths, rhE_norm));
  }
 
  if (conf.exists("allCellsPositionCalc")) {
    const edm::ParameterSet& acConf = conf.getParameterSet("allCellsPositionCalc");
    const std::string& algoac = acConf.getParameter<std::string>("algoName");
    _allCellsPosCalc = PFCPositionCalculatorFactory::get()->create(algoac, acConf);
  }
  // if necessary a third pos calc for convergence testing
  if (conf.exists("positionCalcForConvergence")) {
    const edm::ParameterSet& convConf = conf.getParameterSet("positionCalcForConvergence");
    const std::string& algoconv = convConf.getParameter<std::string>("algoName");
    _convergencePosCalc = PFCPositionCalculatorFactory::get()->create(algoconv, convConf);
  }
}
 
void Basic2DGenericPFlowClusterizer::buildClusters(const reco::PFClusterCollection& input,
                                                   const std::vector<bool>& seedable,
                                                   reco::PFClusterCollection& output) {
  reco::PFClusterCollection clustersInTopo;
  for (const auto& topocluster : input) {
    clustersInTopo.clear();
    seedPFClustersFromTopo(topocluster, seedable, clustersInTopo);
    const unsigned tolScal = std::pow(std::max(1.0, clustersInTopo.size() - 1.0), 2.0);
    growPFClusters(topocluster, seedable, tolScal, 0, tolScal, clustersInTopo);
    // step added by Josh Bendavid, removes low-fraction clusters
    // did not impact position resolution with fraction cut of 1e-7
    // decreases the size of each pf cluster considerably
    prunePFClusters(clustersInTopo);
    // recalculate the positions of the pruned clusters
    if (_convergencePosCalc) {
      // if defined, use the special position calculation for convergence tests
      _convergencePosCalc->calculateAndSetPositions(clustersInTopo);
    } else {
      if (clustersInTopo.size() == 1 && _allCellsPosCalc) {
        _allCellsPosCalc->calculateAndSetPosition(clustersInTopo.back());
      } else {
        _positionCalc->calculateAndSetPositions(clustersInTopo);
      }
    }
    for (auto& clusterout : clustersInTopo) {
      output.insert(output.end(), std::move(clusterout));
    }
  }
}
 
void Basic2DGenericPFlowClusterizer::seedPFClustersFromTopo(const reco::PFCluster& topo,
                                                            const std::vector<bool>& seedable,
                                                            reco::PFClusterCollection& initialPFClusters) const {
  const auto& recHitFractions = topo.recHitFractions();
  for (const auto& rhf : recHitFractions) {
    if (!seedable[rhf.recHitRef().key()])
      continue;
    initialPFClusters.push_back(reco::PFCluster());
    reco::PFCluster& current = initialPFClusters.back();
    current.addRecHitFraction(rhf);
    current.setSeed(rhf.recHitRef()->detId());
    if (_convergencePosCalc) {
      _convergencePosCalc->calculateAndSetPosition(current);
    } else {
      _positionCalc->calculateAndSetPosition(current);
    }
  }
}
 
void Basic2DGenericPFlowClusterizer::growPFClusters(const reco::PFCluster& topo,
                                                    const std::vector<bool>& seedable,
                                                    const unsigned toleranceScaling,
                                                    const unsigned iter,
                                                    double diff,
                                                    reco::PFClusterCollection& clusters) const {
  if (iter >= _maxIterations) {
    LOGDRESSED("Basic2DGenericPFlowClusterizer:growAndStabilizePFClusters")
        << "reached " << _maxIterations << " iterations, terminated position "
        << "fit with diff = " << diff;
  }
  if (iter >= _maxIterations || diff <= _stoppingTolerance * toleranceScaling)
    return;
  // reset the rechits in this cluster, keeping the previous position
  std::vector<reco::PFCluster::REPPoint> clus_prev_pos;
  for (auto& cluster : clusters) {
    const reco::PFCluster::REPPoint& repp = cluster.positionREP();
    clus_prev_pos.emplace_back(repp.rho(), repp.eta(), repp.phi());
    if (_convergencePosCalc) {
      if (clusters.size() == 1 && _allCellsPosCalc) {
        _allCellsPosCalc->calculateAndSetPosition(cluster);
      } else {
        _positionCalc->calculateAndSetPosition(cluster);
      }
    }
    cluster.resetHitsAndFractions();
  }
  // loop over topo cluster and grow current PFCluster hypothesis
  std::vector<double> dist2, frac;
  double fractot = 0;
  for (const reco::PFRecHitFraction& rhf : topo.recHitFractions()) {
    const reco::PFRecHitRef& refhit = rhf.recHitRef();
    int cell_layer = (int)refhit->layer();
    if (cell_layer == PFLayer::HCAL_BARREL2 && std::abs(refhit->positionREP().eta()) > 0.34) {
      cell_layer *= 100;
    }
 
    math::XYZPoint topocellpos_xyz(refhit->position());
    dist2.clear();
    frac.clear();
    fractot = 0;
 
    double recHitEnergyNorm = 0.;
    auto const& recHitEnergyNormDepthPair = _recHitEnergyNorms.find(cell_layer)->second;
 
    for (unsigned int j = 0; j < recHitEnergyNormDepthPair.second.size(); ++j) {
      int depth = recHitEnergyNormDepthPair.first[j];
 
      if ((cell_layer == PFLayer::HCAL_BARREL1 && refhit->depth() == depth) ||
          (cell_layer == PFLayer::HCAL_ENDCAP && refhit->depth() == depth) ||
          (cell_layer != PFLayer::HCAL_ENDCAP && cell_layer != PFLayer::HCAL_BARREL1))
        recHitEnergyNorm = recHitEnergyNormDepthPair.second[j];
    }
 
    // add rechits to clusters, calculating fraction based on distance
    for (auto& cluster : clusters) {
      const math::XYZPoint& clusterpos_xyz = cluster.position();
      const math::XYZVector deltav = clusterpos_xyz - topocellpos_xyz;
      const double d2 = deltav.Mag2() / _showerSigma2;
      dist2.emplace_back(d2);
      if (d2 > 100) {
        LOGDRESSED("Basic2DGenericPFlowClusterizer:growAndStabilizePFClusters")
            << "Warning! :: pfcluster-topocell distance is too large! d= " << d2;
      }
 
      // fraction assignment logic
      double fraction;
      if (refhit->detId() == cluster.seed() && _excludeOtherSeeds) {
        fraction = 1.0;
      } else if (seedable[refhit.key()] && _excludeOtherSeeds) {
        fraction = 0.0;
      } else {
        fraction = cluster.energy() / recHitEnergyNorm * vdt::fast_expf(-0.5 * d2);
      }
      fractot += fraction;
      frac.emplace_back(fraction);
    }
    for (unsigned i = 0; i < clusters.size(); ++i) {
      if (fractot > _minFracTot || (refhit->detId() == clusters[i].seed() && fractot > 0.0)) {
        frac[i] /= fractot;
      } else {
        continue;
      }
      // if the fraction has been set to 0, the cell
      // is now added to the cluster - careful ! (PJ, 19/07/08)
      // BUT KEEP ONLY CLOSE CELLS OTHERWISE MEMORY JUST EXPLOSES
      // (PJ, 15/09/08 <- similar to what existed before the
      // previous bug fix, but keeps the close seeds inside,
      // even if their fraction was set to zero.)
      // Also add a protection to keep the seed in the cluster
      // when the latter gets far from the former. These cases
      // (about 1% of the clusters) need to be studied, as
      // they create fake photons, in general.
      // (PJ, 16/09/08)
      if (dist2[i] < 100.0 || frac[i] > 0.9999) {
        clusters[i].addRecHitFraction(reco::PFRecHitFraction(refhit, frac[i]));
      }
    }
  }
  // recalculate positions and calculate convergence parameter
  double diff2 = 0.0;
  for (unsigned i = 0; i < clusters.size(); ++i) {
    if (_convergencePosCalc) {
      _convergencePosCalc->calculateAndSetPosition(clusters[i]);
    } else {
      if (clusters.size() == 1 && _allCellsPosCalc) {
        _allCellsPosCalc->calculateAndSetPosition(clusters[i]);
      } else {
        _positionCalc->calculateAndSetPosition(clusters[i]);
      }
    }
    const double delta2 = reco::deltaR2(clusters[i].positionREP(), clus_prev_pos[i]);
    if (delta2 > diff2)
      diff2 = delta2;
  }
  diff = std::sqrt(diff2);
  dist2.clear();
  frac.clear();
  clus_prev_pos.clear();  // avoid badness
  growPFClusters(topo, seedable, toleranceScaling, iter + 1, diff, clusters);
}
 
void Basic2DGenericPFlowClusterizer::prunePFClusters(reco::PFClusterCollection& clusters) const {
  for (auto& cluster : clusters) {
    cluster.pruneUsing([&](const reco::PFRecHitFraction& rhf) { return rhf.fraction() > _minFractionToKeep; });
  }
}