JetCoreClusterSplitter.cc

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#include "FWCore/Framework/interface/stream/EDProducer.h"

#include "FWCore/Framework/interface/Event.h"
#include "FWCore/ParameterSet/interface/ParameterSet.h"
#include "FWCore/Utilities/interface/InputTag.h"
#include "DataFormats/Common/interface/Handle.h"
#include "FWCore/Framework/interface/ESHandle.h"
#include "DataFormats/SiPixelCluster/interface/SiPixelCluster.h"
#include "DataFormats/Common/interface/DetSetVectorNew.h"

#include "RecoLocalTracker/ClusterParameterEstimator/interface/PixelClusterParameterEstimator.h"
#include "RecoLocalTracker/Records/interface/TkPixelCPERecord.h"

#include "Geometry/CommonDetUnit/interface/GlobalTrackingGeometry.h"
#include "Geometry/Records/interface/GlobalTrackingGeometryRecord.h"
#include "DataFormats/GeometryVector/interface/VectorUtil.h"

#include "DataFormats/VertexReco/interface/Vertex.h"
#include "DataFormats/VertexReco/interface/VertexFwd.h"
#include "DataFormats/JetReco/interface/Jet.h"

#include <algorithm>
#include <vector>
#include <utility>

class JetCoreClusterSplitter : public edm::stream::EDProducer<> {
 public:
  JetCoreClusterSplitter(const edm::ParameterSet& iConfig);
  ~JetCoreClusterSplitter() override;
  void produce(edm::Event& iEvent, const edm::EventSetup& iSetup) override;

 private:
  bool split(const SiPixelCluster& aCluster,
             edmNew::DetSetVector<SiPixelCluster>::FastFiller& filler,
             float expectedADC, int sizeY, int sizeX, float jetZOverRho);
  std::vector<SiPixelCluster> fittingSplit(const SiPixelCluster& aCluster,
                                           float expectedADC, int sizeY,
                                           int sizeX, float jetZOverRho,
                                           unsigned int nSplitted);
  std::pair<float, float> closestClusters(
      const std::vector<float>& distanceMap);
  std::multimap<float, int> secondDistDiffScore(
      const std::vector<std::vector<float> >& distanceMap);
  std::multimap<float, int> secondDistScore(
      const std::vector<std::vector<float> >& distanceMap);
  std::multimap<float, int> distScore(
      const std::vector<std::vector<float> >& distanceMap);
  bool verbose;
  std::string pixelCPE_;
  double ptMin_;
  double deltaR_;
  double chargeFracMin_;
  edm::EDGetTokenT<edmNew::DetSetVector<SiPixelCluster> > pixelClusters_;
  edm::EDGetTokenT<reco::VertexCollection> vertices_;
  edm::EDGetTokenT<edm::View<reco::Candidate> > cores_;
  double forceXError_;
  double forceYError_;
  double fractionalWidth_;
  double chargePerUnit_;
  double centralMIPCharge_;
};

JetCoreClusterSplitter::JetCoreClusterSplitter(const edm::ParameterSet& iConfig)
    : verbose(iConfig.getParameter<bool>("verbose")),
      pixelCPE_(iConfig.getParameter<std::string>("pixelCPE")),
      ptMin_(iConfig.getParameter<double>("ptMin")),
      deltaR_(iConfig.getParameter<double>("deltaRmax")),
      chargeFracMin_(iConfig.getParameter<double>("chargeFractionMin")),
      pixelClusters_(consumes<edmNew::DetSetVector<SiPixelCluster> >(
          iConfig.getParameter<edm::InputTag>("pixelClusters"))),
      vertices_(consumes<reco::VertexCollection>(
          iConfig.getParameter<edm::InputTag>("vertices"))),
      cores_(consumes<edm::View<reco::Candidate> >(
          iConfig.getParameter<edm::InputTag>("cores"))),
      forceXError_(iConfig.getParameter<double>("forceXError")),
      forceYError_(iConfig.getParameter<double>("forceYError")),
      fractionalWidth_(iConfig.getParameter<double>("fractionalWidth")),
      chargePerUnit_(iConfig.getParameter<double>("chargePerUnit")),
      centralMIPCharge_(iConfig.getParameter<double>("centralMIPCharge"))

{
  produces<edmNew::DetSetVector<SiPixelCluster> >();
}

JetCoreClusterSplitter::~JetCoreClusterSplitter() {}

bool SortPixels(const SiPixelCluster::Pixel& i,
                const SiPixelCluster::Pixel& j) {
  return (i.adc > j.adc);
}

void JetCoreClusterSplitter::produce(edm::Event& iEvent,
                                     const edm::EventSetup& iSetup) {
  using namespace edm;
  edm::ESHandle<GlobalTrackingGeometry> geometry;
  iSetup.get<GlobalTrackingGeometryRecord>().get(geometry);

  Handle<edmNew::DetSetVector<SiPixelCluster> > inputPixelClusters;
  iEvent.getByToken(pixelClusters_, inputPixelClusters);

  Handle<std::vector<reco::Vertex> > vertices;
  iEvent.getByToken(vertices_, vertices);
  const reco::Vertex& pv = (*vertices)[0];

  Handle<edm::View<reco::Candidate> > cores;
  iEvent.getByToken(cores_, cores);

  edm::ESHandle<PixelClusterParameterEstimator> pe;
  const PixelClusterParameterEstimator* pp;
  iSetup.get<TkPixelCPERecord>().get(pixelCPE_, pe);
  pp = pe.product();

  auto output = std::make_unique<edmNew::DetSetVector<SiPixelCluster>>();

  edmNew::DetSetVector<SiPixelCluster>::const_iterator detIt =
      inputPixelClusters->begin();
  for (; detIt != inputPixelClusters->end(); detIt++) {
    edmNew::DetSetVector<SiPixelCluster>::FastFiller filler(*output,
                                                            detIt->id());
    const edmNew::DetSet<SiPixelCluster>& detset = *detIt;
    const GeomDet* det = geometry->idToDet(detset.id());
    for (auto cluster = detset.begin();
         cluster != detset.end(); cluster++) {
      const SiPixelCluster& aCluster = *cluster;
      bool hasBeenSplit = false;
      bool shouldBeSplit = false;
      GlobalPoint cPos = det->surface().toGlobal(
          pp->localParametersV(aCluster,
                               (*geometry->idToDetUnit(detIt->id())))[0].first);
      GlobalPoint ppv(pv.position().x(), pv.position().y(), pv.position().z());
      GlobalVector clusterDir = cPos - ppv;
      for (unsigned int ji = 0; ji < cores->size(); ji++) {
        if ((*cores)[ji].pt() > ptMin_) {
          const reco::Candidate& jet = (*cores)[ji];
          GlobalVector jetDir(jet.px(), jet.py(), jet.pz());
          if (Geom::deltaR(jetDir, clusterDir) < deltaR_) {
            // check if the cluster has to be splitted

            bool isEndCap =
                (std::abs(cPos.z()) > 30.f);  // FIXME: check detID instead!
            float jetZOverRho = jet.momentum().Z() / jet.momentum().Rho();
            if (isEndCap)
              jetZOverRho = jet.momentum().Rho() / jet.momentum().Z();
            float expSizeY =
                std::sqrt((1.3f*1.3f) + (1.9f*1.9f) * jetZOverRho*jetZOverRho);
            if (expSizeY < 1.f) expSizeY = 1.f;
            float expSizeX = 1.5f;
            if (isEndCap) {
              expSizeX = expSizeY;
              expSizeY = 1.5f;
            }  // in endcap col/rows are switched
            float expCharge =
                std::sqrt(1.08f + jetZOverRho * jetZOverRho) * centralMIPCharge_;

            if (aCluster.charge() > expCharge * chargeFracMin_ &&
                (aCluster.sizeX() > expSizeX + 1 ||
                 aCluster.sizeY() > expSizeY + 1)) {
              shouldBeSplit = true;
              if (verbose)
                std::cout << "Trying to split: charge and deltaR "
                          << aCluster.charge() << " "
                          << Geom::deltaR(jetDir, clusterDir) << " size x y "
                          << aCluster.sizeX() << " " << aCluster.sizeY()
                          << " exp. size (x,y) "
                          << expSizeX << " " << expSizeY
                          << " detid " << detIt->id() << std::endl;
              if (verbose)
                std::cout << "jetZOverRho=" << jetZOverRho << std::endl;

              if (split(aCluster, filler, expCharge, expSizeY, expSizeX,
                        jetZOverRho)) {
                hasBeenSplit = true;
              }
            }
          }
        }
      }
      if (!hasBeenSplit) {
        SiPixelCluster c = aCluster;
        if (shouldBeSplit) {
          // blowup the error if we failed to split a splittable cluster (does
          // it ever happen)
          c.setSplitClusterErrorX(c.sizeX() * (100.f/3.f));  // this is not really blowing up .. TODO: tune
          c.setSplitClusterErrorY(c.sizeY() * (150.f/3.f));
        }
        filler.push_back(c);
        std::push_heap(filler.begin(),filler.end(),
          [](SiPixelCluster const & cl1,SiPixelCluster const & cl2) { return cl1.minPixelRow() < cl2.minPixelRow();});

      }
    }// loop over clusters
    std::sort_heap(filler.begin(),filler.end(),
          [](SiPixelCluster const & cl1,SiPixelCluster const & cl2) { return cl1.minPixelRow() < cl2.minPixelRow();});

  }  // loop over det
  iEvent.put(std::move(output));
}

bool JetCoreClusterSplitter::split(
    const SiPixelCluster& aCluster,
    edmNew::DetSetVector<SiPixelCluster>::FastFiller& filler, float expectedADC,
    int sizeY, int sizeX, float jetZOverRho) {
  // This function should test several configuration of splitting, and then
  // return the one with best chi2

  std::vector<SiPixelCluster> sp =
      fittingSplit(aCluster, expectedADC, sizeY, sizeX, jetZOverRho,
                   std::floor(aCluster.charge() / expectedADC + 0.5f));

  // for the config with best chi2
  for (unsigned int i = 0; i < sp.size(); i++) {
    filler.push_back(sp[i]);
    std::push_heap(filler.begin(),filler.end(),
          [](SiPixelCluster const & cl1,SiPixelCluster const & cl2) { return cl1.minPixelRow() < cl2.minPixelRow();});
  }

  return (!sp.empty());
}

// order with fast algo and pick first and second instead?
std::pair<float, float> JetCoreClusterSplitter::closestClusters(
    const std::vector<float>& distanceMap) {
  float minDist = std::numeric_limits<float>::max();
  float secondMinDist = std::numeric_limits<float>::max();
  for (unsigned int i = 0; i < distanceMap.size(); i++) {
    float dist = distanceMap[i];
    if (dist < minDist) {
      secondMinDist = minDist;
      minDist = dist;
    } else if (dist < secondMinDist) {
      secondMinDist = dist;
    }
  }
  return std::pair<float, float>(minDist, secondMinDist);
}

std::multimap<float, int> JetCoreClusterSplitter::secondDistDiffScore(
    const std::vector<std::vector<float> >& distanceMap) {
  std::multimap<float, int> scores;
  for (unsigned int j = 0; j < distanceMap.size(); j++) {
    std::pair<float, float> d = closestClusters(distanceMap[j]);
    scores.insert(std::pair<float, int>(d.second - d.first, j));
  }
  return scores;
}

std::multimap<float, int> JetCoreClusterSplitter::secondDistScore(
    const std::vector<std::vector<float> >& distanceMap) {
  std::multimap<float, int> scores;
  for (unsigned int j = 0; j < distanceMap.size(); j++) {
    std::pair<float, float> d = closestClusters(distanceMap[j]);
    scores.insert(std::pair<float, int>(-d.second, j));
  }
  return scores;
}

std::multimap<float, int> JetCoreClusterSplitter::distScore(
    const std::vector<std::vector<float> >& distanceMap) {
  std::multimap<float, int> scores;
  for (unsigned int j = 0; j < distanceMap.size(); j++) {
    std::pair<float, float> d = closestClusters(distanceMap[j]);
    scores.insert(std::pair<float, int>(-d.first, j));
  }
  return scores;
}

std::vector<SiPixelCluster> JetCoreClusterSplitter::fittingSplit(
    const SiPixelCluster& aCluster, float expectedADC, int sizeY, int sizeX,
    float jetZOverRho, unsigned int nSplitted) {
  std::vector<SiPixelCluster> output;

  unsigned int meanExp = nSplitted;
  if (meanExp <= 1) {
    output.push_back(aCluster);
    return output;
  }

  std::vector<float> clx(meanExp);
  std::vector<float> cly(meanExp);
  std::vector<float> cls(meanExp);
  std::vector<float> oldclx(meanExp);
  std::vector<float> oldcly(meanExp);
  std::vector<SiPixelCluster::Pixel> originalpixels = aCluster.pixels();
  std::vector<std::pair<int, SiPixelCluster::Pixel> > pixels;
  for (unsigned int j = 0; j < originalpixels.size(); j++) {
    int sub = originalpixels[j].adc / chargePerUnit_ * expectedADC /
              centralMIPCharge_;
    if (sub < 1) sub = 1;
    int perDiv = originalpixels[j].adc / sub;
    if (verbose)
      std::cout << "Splitting  " << j << "  in [ " << pixels.size() << " , "
                << pixels.size() + sub << " ], expected numb of clusters: "
                << meanExp << " original pixel (x,y) "
                << originalpixels[j].x << " " << originalpixels[j].y
                << " sub " << sub << std::endl;
    for (int k = 0; k < sub; k++) {
      if (k == sub - 1) perDiv = originalpixels[j].adc - perDiv * k;
      pixels.push_back(std::make_pair(j, SiPixelCluster::Pixel(originalpixels[j].x,
                                                               originalpixels[j].y, perDiv)));
    }
  }
  std::vector<int> clusterForPixel(pixels.size());
  // initial values
  for (unsigned int j = 0; j < meanExp; j++) {
    oldclx[j] = -999;
    oldcly[j] = -999;
    clx[j] = originalpixels[0].x + j;
    cly[j] = originalpixels[0].y + j;
    cls[j] = 0;
  }
  bool stop = false;
  int remainingSteps = 100;
  while (!stop && remainingSteps > 0) {
    remainingSteps--;
    // Compute all distances
    std::vector<std::vector<float> > distanceMapX(originalpixels.size(),
                                                  std::vector<float>(meanExp));
    std::vector<std::vector<float> > distanceMapY(originalpixels.size(),
                                                  std::vector<float>(meanExp));
    std::vector<std::vector<float> > distanceMap(originalpixels.size(),
                                                 std::vector<float>(meanExp));
    for (unsigned int j = 0; j < originalpixels.size(); j++) {
      if (verbose)
        std::cout << "Original Pixel pos " << j << " " << pixels[j].second.x << " "
                  << pixels[j].second.y << std::endl;
      for (unsigned int i = 0; i < meanExp; i++) {
        distanceMapX[j][i] = 1.f * originalpixels[j].x - clx[i];
        distanceMapY[j][i] = 1.f * originalpixels[j].y - cly[i];
        float dist = 0;
        //              float sizeX=2;
        if (std::abs(distanceMapX[j][i]) >  sizeX/2.f) {
          dist += (std::abs(distanceMapX[j][i]) - sizeX/2.f + 1.f) *
                  (std::abs(distanceMapX[j][i]) - sizeX/2.f + 1.f);
        } else {
          dist +=
              (2.f*distanceMapX[j][i]/sizeX)*(2.f*distanceMapX[j][i]/sizeX);
        }

        if (std::abs(distanceMapY[j][i]) > sizeY/2.f) {
          dist += 1.f * (std::abs(distanceMapY[j][i]) - sizeY/2.f + 1.f) *
                        (std::abs(distanceMapY[j][i]) - sizeY/2.f + 1.f);
        } else {
          dist += 1.f * (2.f*distanceMapY[j][i]/sizeY) * 
                        (2.f*distanceMapY[j][i]/sizeY);
        }
        distanceMap[j][i] = sqrt(dist);
        if (verbose)
          std::cout << "Cluster " << i << " Original Pixel " << j
                    << " distances: " << distanceMapX[j][i] << " "
                    << distanceMapY[j][i] << " " << distanceMap[j][i]
                    << std::endl;
      }
    }
    // Compute scores for sequential addition. The first index is the
    // distance, in whatever metrics we use, while the second is the
    // pixel index w.r.t which the distance is computed.
    std::multimap<float, int> scores;

    // Using different rankings to improve convergence (as Giulio proposed)
    scores = secondDistScore(distanceMap);

    // Iterate starting from the ones with furthest second best clusters, i.e.
    // easy choices
    std::vector<float> weightOfPixel(pixels.size());
    for (std::multimap<float, int>::iterator it = scores.begin();
         it != scores.end(); it++) {
      int pixel_index = it->second;
      if (verbose)
        std::cout << "Original Pixel " << pixel_index << " with score " << it->first << std::endl;
      // find cluster that is both close and has some charge still to assign
      int subpixel_counter = 0;
      for (auto subpixel = pixels.begin(); subpixel != pixels.end();
           ++subpixel, ++subpixel_counter) {
        if (subpixel->first > pixel_index) {
          break;
        } else if (subpixel->first != pixel_index) {
          continue;
        } else {
          float maxEst = 0;
          int cl = -1;
          for (unsigned int subcluster_index = 0;
               subcluster_index < meanExp; subcluster_index++) {
            float nsig =
                (cls[subcluster_index] - expectedADC) /
                (expectedADC *
                 fractionalWidth_);  // 20% uncertainty? realistic from Landau?
            float clQest = 1.f / (1.f + std::exp(nsig)) + 1e-6f;  // 1./(1.+exp(x*x-3*3))
            float clDest = 1.f / (distanceMap[pixel_index][subcluster_index] + 0.05f);

            if (verbose)
              std::cout << " Q: " << clQest << " D: " << clDest << " "
                        << distanceMap[pixel_index][subcluster_index] << std::endl;
            float est = clQest * clDest;
            if (est > maxEst) {
              cl = subcluster_index;
              maxEst = est;
            }
          }
          cls[cl] += subpixel->second.adc;
          clusterForPixel[subpixel_counter] = cl;
          weightOfPixel[subpixel_counter] = maxEst;
          if (verbose)
            std::cout << "Pixel weight j cl " << weightOfPixel[subpixel_counter]
                      << " " << subpixel_counter
                      << " " << cl << std::endl;
        }
      }
    }
    // Recompute cluster centers
    stop = true;
    for (unsigned int subcluster_index = 0;
         subcluster_index < meanExp; subcluster_index++) {
      if (std::abs(clx[subcluster_index] - oldclx[subcluster_index]) > 0.01f)
        stop = false;  // still moving
      if (std::abs(cly[subcluster_index] - oldcly[subcluster_index]) > 0.01f)
        stop = false;
      oldclx[subcluster_index] = clx[subcluster_index];
      oldcly[subcluster_index] = cly[subcluster_index];
      clx[subcluster_index] = 0;
      cly[subcluster_index] = 0;
      cls[subcluster_index] = 1e-99;
    }
    for (unsigned int pixel_index = 0;
         pixel_index < pixels.size(); pixel_index++) {
      if (clusterForPixel[pixel_index] < 0) continue;
      if (verbose)
        std::cout << "j " << pixel_index << " x " << pixels[pixel_index].second.x << " * y "
                  << pixels[pixel_index].second.y << " * ADC "
                  << pixels[pixel_index].second.adc << " * W "
                  << weightOfPixel[pixel_index] << std::endl;
      clx[clusterForPixel[pixel_index]] += pixels[pixel_index].second.x * pixels[pixel_index].second.adc;
      cly[clusterForPixel[pixel_index]] += pixels[pixel_index].second.y * pixels[pixel_index].second.adc;
      cls[clusterForPixel[pixel_index]] += pixels[pixel_index].second.adc;
    }
    for (unsigned int subcluster_index = 0;
         subcluster_index < meanExp; subcluster_index++) {
      if (cls[subcluster_index] != 0) {
        clx[subcluster_index] /= cls[subcluster_index];
        cly[subcluster_index] /= cls[subcluster_index];
      }
      if (verbose)
        std::cout << "Center for cluster " << subcluster_index << " x,y "
                  << clx[subcluster_index] << " "
                  << cly[subcluster_index] << std::endl;
      cls[subcluster_index] = 0;
    }
  }
  if (verbose) std::cout << "maxstep " << remainingSteps << std::endl;
  // accumulate pixel with same cl
  std::vector<std::vector<SiPixelCluster::Pixel> > pixelsForCl(meanExp);
  for (int cl = 0; cl < (int)meanExp; cl++) {
    for (unsigned int j = 0; j < pixels.size(); j++) {
      if (clusterForPixel[j] == cl and
          pixels[j].second.adc != 0) {  // for each pixel of cluster
                                        // cl find the other pixels
                                        // with same x,y and
                                        // accumulate+reset their adc
        for (unsigned int k = j + 1; k < pixels.size(); k++) {
          if (pixels[k].second.adc != 0
              and pixels[k].second.x == pixels[j].second.x
              and pixels[k].second.y == pixels[j].second.y
              and clusterForPixel[k] == cl) {
            if (verbose)
              std::cout << "Resetting all sub-pixel for location "
                        << pixels[k].second.x << ", " << pixels[k].second.y
                        << " at index " << k << " associated to cl "
                        << clusterForPixel[k] << std::endl;
            pixels[j].second.adc += pixels[k].second.adc;
            pixels[k].second.adc = 0;
          }
        }
        for (unsigned int p = 0; p < pixels.size(); ++p)
          if (verbose)
            std::cout << "index, x, y, ADC: " << p << ", "
                      << pixels[p].second.x << ", " << pixels[p].second.y
                      << ", " << pixels[p].second.adc
                      << " associated to cl " << clusterForPixel[p] << std::endl
                      << "Adding pixel " << pixels[j].second.x << ", " << pixels[j].second.y
                  << " to cluster " << cl << std::endl;
        pixelsForCl[cl].push_back(pixels[j].second);
      }
    }
  }

  //    std::vector<std::vector<std::vector<SiPixelCluster::PixelPos *> > >
  //pixelMap(meanExp,std::vector<std::vector<SiPixelCluster::PixelPos *>
  //>(512,std::vector<SiPixelCluster::Pixel *>(512,0)));

  for (int cl = 0; cl < (int)meanExp; cl++) {
    if (verbose) std::cout << "Pixels of cl " << cl << " ";
    for (unsigned int j = 0; j < pixelsForCl[cl].size(); j++) {
        SiPixelCluster::PixelPos newpix(pixelsForCl[cl][j].x,
                                        pixelsForCl[cl][j].y);
      if (verbose)
        std::cout << pixelsForCl[cl][j].x << "," << pixelsForCl[cl][j].y << "|";
      if (j==0) {
        output.emplace_back(newpix, pixelsForCl[cl][j].adc);
      } else {
        output.back().add(newpix, pixelsForCl[cl][j].adc);
      }
    }
    if (verbose) std::cout << std::endl;
    if (!pixelsForCl[cl].empty()) {
      if (forceXError_ > 0) output.back().setSplitClusterErrorX(forceXError_);
      if (forceYError_ > 0) output.back().setSplitClusterErrorY(forceYError_);
    }
  }
  //    if(verbose) std::cout << "Weights" << std::endl;
  //    if(verbose) print(theWeights,aCluster,1);
  //    if(verbose) std::cout << "Unused charge" << std::endl;
  //    if(verbose) print(theBufferResidual,aCluster);

  return output;
}

#include "FWCore/PluginManager/interface/ModuleDef.h"
#include "FWCore/Framework/interface/MakerMacros.h"
DEFINE_FWK_MODULE(JetCoreClusterSplitter);