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File indexing completed on 2024-09-07 04:37:39

 /**
  * \file CSCSegAlgoTC.cc
  *
  * Last update: 13.02.2015
  *
  */
 
 #include "CSCSegAlgoTC.h"
 #include "CSCSegFit.h"
 
 #include "DataFormats/CSCRecHit/interface/CSCSegment.h"
 #include "DataFormats/GeometryVector/interface/GlobalPoint.h"
 
 #include "Geometry/CSCGeometry/interface/CSCLayer.h"
 
 #include "FWCore/ParameterSet/interface/ParameterSet.h"
 #include "FWCore/MessageLogger/interface/MessageLogger.h"
 
 #include "CommonTools/Statistics/interface/ChiSquaredProbability.h"
 
 #include <algorithm>
 #include <cmath>
 #include <iostream>
 #include <string>
 
 CSCSegAlgoTC::CSCSegAlgoTC(const edm::ParameterSet& ps)
     : CSCSegmentAlgorithm(ps), sfit_(nullptr), myName("CSCSegAlgoTC") {
   debugInfo = ps.getUntrackedParameter<bool>("verboseInfo");
 
   dRPhiMax = ps.getParameter<double>("dRPhiMax");
   dPhiMax = ps.getParameter<double>("dPhiMax");
   dRPhiFineMax = ps.getParameter<double>("dRPhiFineMax");
   dPhiFineMax = ps.getParameter<double>("dPhiFineMax");
   chi2Max = ps.getParameter<double>("chi2Max");
   chi2ndfProbMin = ps.getParameter<double>("chi2ndfProbMin");
   minLayersApart = ps.getParameter<int>("minLayersApart");
   SegmentSorting = ps.getParameter<int>("SegmentSorting");
 
   LogDebug("CSC") << myName << " has algorithm cuts set to: \n"
                   << "--------------------------------------------------------------------\n"
                   << "dRPhiMax     = " << dRPhiMax << '\n'
                   << "dPhiMax      = " << dPhiMax << '\n'
                   << "dRPhiFineMax = " << dRPhiFineMax << '\n'
                   << "dPhiFineMax  = " << dPhiFineMax << '\n'
                   << "chi2Max      = " << chi2Max << '\n'
                   << "chi2ndfProbMin = " << chi2ndfProbMin << '\n'
                   << "minLayersApart = " << minLayersApart << '\n'
                   << "SegmentSorting = " << SegmentSorting << std::endl;
 }
 
 std::vector<CSCSegment> CSCSegAlgoTC::run(const CSCChamber* aChamber, const ChamberHitContainer& rechits) {
   theChamber = aChamber;
 
   return buildSegments(rechits);
 }
 
 std::vector<CSCSegment> CSCSegAlgoTC::buildSegments(const ChamberHitContainer& urechits) {
   //  ChamberHitContainer rechits = urechits;
   ChamberHitContainer rechits(urechits);
 
   //  edm::LogVerbatim("CSCSegment") << "[CSCSegAlgoTC::buildSegments] start building segments in " << theChamber->id();
   //  edm::LogVerbatim("CSCSegment") << "[CSCSegAlgoTC::buildSegments] size of rechit container = " << rechits.size();
 
   if (rechits.size() < 2) {
     LogDebug("CSC") << myName << ": " << rechits.size() << "     hit(s) in chamber is not enough to build a segment.\n";
     return std::vector<CSCSegment>();
   }
 
   LayerIndex layerIndex(rechits.size());
 
   for (size_t i = 0; i < rechits.size(); ++i) {
     short ilay = rechits[i]->cscDetId().layer();
     layerIndex[i] = ilay;
     //    edm::LogVerbatim("CSCSegment") << "layerIndex[" << i << "] should   be " << rechits[i]->cscDetId().layer();
     //    edm::LogVerbatim("CSCSegment") << "layerIndex[" << i << "] actually is " << layerIndex[i];
   }
 
   double z1 = theChamber->layer(1)->position().z();
   double z6 = theChamber->layer(6)->position().z();
 
   if (z1 > 0.) {
     if (z1 > z6) {
       reverse(layerIndex.begin(), layerIndex.end());
       reverse(rechits.begin(), rechits.end());
     }
   } else if (z1 < 0.) {
     if (z1 < z6) {
       reverse(layerIndex.begin(), layerIndex.end());
       reverse(rechits.begin(), rechits.end());
     }
   }
 
   // Dump rechits after sorting?
   //  if (debugInfo) dumpHits(rechits);
 
   //  if (rechits.size() < 2) {
   //    LogDebug("CSC") << myName << ": " << rechits.size() <<
   //      "  hit(s) in chamber is not enough to build a segment.\n";
   //    return std::vector<CSCSegment>();
   //  }
 
   // We have at least 2 hits. We intend to try all possible pairs of hits to start
   // segment building. 'All possible' means each hit lies on different layers in the chamber.
   // For now we don't care whether a hit has already been allocated to another segment;
   // we'll sort that out after building all possible segments.
 
   // Choose first hit (as close to IP as possible) h1 and
   // second hit (as far from IP as possible) h2
   // To do this we iterate over hits in the chamber by layer - pick two layers.
   // @@ Require the two layers are at least 3 layers apart. May need tuning?
   // Then we iterate over hits within each of these layers and pick h1 and h2 from these.
   // If they are 'close enough' we build an empty segment.
   // Then try adding hits to this segment.
 
   // Define buffer for segments we build (at the end we'll sort them somehow, and remove
   // those which share hits with better-quality segments.
 
   std::vector<CSCSegment> segments;
 
   sfit_ = nullptr;
 
   ChamberHitContainerCIt ib = rechits.begin();
   ChamberHitContainerCIt ie = rechits.end();
 
   for (ChamberHitContainerCIt i1 = ib; i1 != ie; ++i1) {
     int layer1 = layerIndex[i1 - ib];
 
     const CSCRecHit2D* h1 = *i1;
 
     for (ChamberHitContainerCIt i2 = ie - 1; i2 != i1; --i2) {
       int layer2 = layerIndex[i2 - ib];
 
       if (abs(layer2 - layer1) < minLayersApart)
         break;
 
       const CSCRecHit2D* h2 = *i2;
 
       if (areHitsCloseInLocalX(h1, h2) && areHitsCloseInGlobalPhi(h1, h2)) {
         proto_segment.clear();
 
         const CSCLayer* l1 = theChamber->layer(h1->cscDetId().layer());
         GlobalPoint gp1 = l1->toGlobal(h1->localPosition());
         const CSCLayer* l2 = theChamber->layer(h2->cscDetId().layer());
         GlobalPoint gp2 = l2->toGlobal(h2->localPosition());
         LogDebug("CSCSegment") << "start new segment from hits "
                                << "h1: " << gp1 << " - h2: " << gp2 << "\n";
         //  edm::LogVerbatim("CSCSegment") << "start new segment from hits " << "h1: " << gp1 << " - h2: " << gp2;
         //  edm::LogVerbatim("CSCSegment") << "on layers " << layer1 << " and " << layer2;
 
         if (!addHit(h1, layer1)) {
           LogDebug("CSCSegment") << "  failed to add hit h1\n";
           continue;
         }
 
         if (!addHit(h2, layer2)) {
           LogDebug("CSCSegment") << "  failed to add hit h2\n";
           continue;
         }
 
         if (sfit_)
           tryAddingHitsToSegment(rechits, i1, i2);  // can only add hits if there's a segment
 
         // if a segment has been found push back it into the segment collection
         if (proto_segment.empty()) {
           LogDebug("CSCSegment") << "No segment found.\n";
           //      edm::LogVerbatim("CSCSegment") << "No segment found.";
         } else {
           //@@ THIS IS GOING TO BE TRICKY - CREATING MANY FITS ON HEAP
           //@@ BUT MEMBER VARIABLE JUST POINTS TO MOST RECENT ONE
           candidates.push_back(sfit_);  // store the current fit
           LogDebug("CSCSegment") << "Found a segment.\n";
           //      edm::LogVerbatim("CSCSegment") << "Found a segment.";
         }
       }
     }
   }
 
   //  edm::LogVerbatim("CSCSegment") << "[CSCSegAlgoTC::buildSegments] no. of candidates before pruning = " << candidates.size();
 
   // We've built all possible segments. Now pick the best, non-overlapping subset.
   pruneTheSegments(rechits);
 
   // Create CSCSegments for the surviving candidates
   for (unsigned int i = 0; i < candidates.size(); ++i) {
     CSCSegFit* sfit = candidates[i];
     //    edm::LogVerbatim("CSCSegment") << "candidate fit " << i+1 << " of " << candidates.size() << " is at " << sfit;
     //    if ( !sfit ) {
     //      edm::LogVerbatim("CSCSegment") << "stored a null pointer for element " << i+1 << " of " << candidates.size();
     //      continue;
     //    }
     CSCSegment temp(sfit->hits(), sfit->intercept(), sfit->localdir(), sfit->covarianceMatrix(), sfit->chi2());
     delete sfit;
     segments.push_back(temp);
     if (debugInfo)
       dumpSegment(temp);
   }
 
   // reset member variables
   candidates.clear();
   sfit_ = nullptr;
 
   //  edm::LogVerbatim("CSCSegment") << "[CSCSegAlgoTC::buildSegments] no. of segments returned = " << segments.size();
 
   return segments;
 }
 
 void CSCSegAlgoTC::tryAddingHitsToSegment(const ChamberHitContainer& rechits,
                                           const ChamberHitContainerCIt i1,
                                           const ChamberHitContainerCIt i2) {
   // Iterate over the layers with hits in the chamber
   // Skip the layers containing the segment endpoints
   // Test each hit on the other layers to see if it is near the segment
   // If it is, see whether there is already a hit on the segment from the same layer
   //    - if so, and there are more than 2 hits on the segment, copy the segment,
   //      replace the old hit with the new hit. If the new segment chi2 is better
   //      then replace the original segment with the new one (by swap)
   //    - if not, copy the segment, add the hit. If the new chi2/dof is still satisfactory
   //      then replace the original segment with the new one (by swap)
 
   ChamberHitContainerCIt ib = rechits.begin();
   ChamberHitContainerCIt ie = rechits.end();
 
   for (ChamberHitContainerCIt i = ib; i != ie; ++i) {
     if (i == i1 || i == i2)
       continue;
 
     int layer = (*i)->cscDetId().layer();
     const CSCRecHit2D* h = *i;
 
     if (isHitNearSegment(h)) {
       const CSCLayer* l1 = theChamber->layer(h->cscDetId().layer());
       GlobalPoint gp1 = l1->toGlobal(h->localPosition());
       LogDebug("CSC") << "    hit at global " << gp1 << " is near segment\n.";
 
       if (hasHitOnLayer(layer)) {
         if (proto_segment.size() <= 2) {
           LogDebug("CSC") << "    " << proto_segment.size() << " hits on segment...skip hit on same layer.\n";
           continue;
         }
 
         compareProtoSegment(h, layer);
       } else
         increaseProtoSegment(h, layer);
     }  // h & seg close
   }  // i
 }
 
 bool CSCSegAlgoTC::addHit(const CSCRecHit2D* aHit, int layer) {
   // Return true if hit was added successfully
   // (and then parameters are updated).
   // Return false if there is already a hit on the same layer, or insert failed.
 
   bool ok = true;
   ChamberHitContainer::const_iterator it;
 
   for (it = proto_segment.begin(); it != proto_segment.end(); it++)
     if (((*it)->cscDetId().layer() == layer) && (aHit != *it))
       return false;
 
   if (ok) {
     proto_segment.push_back(aHit);
     updateParameters();
   }
   return ok;
 }
 
 bool CSCSegAlgoTC::replaceHit(const CSCRecHit2D* h, int layer) {
   // replace a hit from a layer
   ChamberHitContainer::iterator it;
   for (it = proto_segment.begin(); it != proto_segment.end();) {
     if ((*it)->cscDetId().layer() == layer)
       it = proto_segment.erase(it);
     else
       ++it;
   }
 
   return addHit(h, layer);
 }
 
 void CSCSegAlgoTC::updateParameters(void) {
   //@@ DO NOT DELETE EXISTING FIT SINCE WE SAVE IT!!
   //  delete sfit_;
   sfit_ = new CSCSegFit(theChamber, proto_segment);
   sfit_->fit();
 }
 
 float CSCSegAlgoTC::phiAtZ(float z) const {
   // Returns a phi in [ 0, 2*pi )
   const CSCLayer* l1 = theChamber->layer(1);
   GlobalPoint gp = l1->toGlobal(sfit_->intercept());
   GlobalVector gv = l1->toGlobal(sfit_->localdir());
 
   float x = gp.x() + (gv.x() / gv.z()) * (z - gp.z());
   float y = gp.y() + (gv.y() / gv.z()) * (z - gp.z());
   float phi = atan2(y, x);
   if (phi < 0.f)
     phi += 2. * M_PI;
 
   return phi;
 }
 
 void CSCSegAlgoTC::compareProtoSegment(const CSCRecHit2D* h, int layer) {
   // Save copy of current fit
   CSCSegFit* oldfit = new CSCSegFit(*sfit_);
 
   bool ok = replaceHit(h, layer);  // possible new fit
 
   if (ok) {
     LogDebug("CSC") << "    hit in same layer as a hit on segment; try replacing old one..."
                     << " chi2 new: " << sfit_->chi2() << " old: " << oldfit->chi2() << "\n";
   }
 
   if (ok && (sfit_->chi2() < oldfit->chi2())) {
     LogDebug("CSC") << "    segment with replaced hit is better.\n";
     delete oldfit;  // new fit is better
   } else {
     delete sfit_;    // new fit is worse
     sfit_ = oldfit;  // restore original fit
   }
 }
 
 void CSCSegAlgoTC::increaseProtoSegment(const CSCRecHit2D* h, int layer) {
   // save copy of input fit
   CSCSegFit* oldfit = new CSCSegFit(*sfit_);
 
   bool ok = addHit(h, layer);  // possible new fit
 
   if (ok) {
     LogDebug("CSC") << "    hit in new layer: added to segment, new chi2: " << sfit_->chi2() << "\n";
   }
 
   //  int ndf = 2*proto_segment.size() - 4;
 
   if (ok && ((sfit_->chi2() <= 0) || (sfit_->chi2() / sfit_->ndof() < chi2Max))) {
     LogDebug("CSC") << "    segment with added hit is good.\n";
     delete oldfit;  // new fit is better
   } else {
     delete sfit_;    // new fit is worse
     sfit_ = oldfit;  // restore original fit
   }
 }
 
 bool CSCSegAlgoTC::areHitsCloseInLocalX(const CSCRecHit2D* h1, const CSCRecHit2D* h2) const {
   float deltaX = (h1->localPosition() - h2->localPosition()).x();
   LogDebug("CSC") << "    Hits at local x= " << h1->localPosition().x() << ", " << h2->localPosition().x()
                   << " have separation= " << deltaX;
   return (fabs(deltaX) < (dRPhiMax)) ? true : false;  // +v
 }
 
 bool CSCSegAlgoTC::areHitsCloseInGlobalPhi(const CSCRecHit2D* h1, const CSCRecHit2D* h2) const {
   const CSCLayer* l1 = theChamber->layer(h1->cscDetId().layer());
   GlobalPoint gp1 = l1->toGlobal(h1->localPosition());
   const CSCLayer* l2 = theChamber->layer(h2->cscDetId().layer());
   GlobalPoint gp2 = l2->toGlobal(h2->localPosition());
 
   float h1p = gp1.phi();
   float h2p = gp2.phi();
   float dphi12 = h1p - h2p;
 
   // Into range [-pi, pi) (phi() returns values in this range)
   if (dphi12 < -M_PI)
     dphi12 += 2. * M_PI;
   if (dphi12 > M_PI)
     dphi12 -= 2. * M_PI;
   LogDebug("CSC") << "    Hits at global phi= " << h1p << ", " << h2p << " have separation= " << dphi12;
   return (fabs(dphi12) < dPhiMax) ? true : false;  // +v
 }
 
 bool CSCSegAlgoTC::isHitNearSegment(const CSCRecHit2D* h) const {
   // Is hit near segment?
   // Requires deltaphi and rxy*deltaphi within ranges specified
   // in orcarc, or by default, where rxy=sqrt(x**2+y**2) of hit itself.
   // Note that to make intuitive cuts on delta(phi) one must work in
   // phi range (-pi, +pi] not [0, 2pi
 
   const CSCLayer* l1 = theChamber->layer(h->cscDetId().layer());
   GlobalPoint hp = l1->toGlobal(h->localPosition());
 
   float hphi = hp.phi();  // in (-pi, +pi]
   if (hphi < 0.)
     hphi += 2. * M_PI;          // into range [0, 2pi)
   float sphi = phiAtZ(hp.z());  // in [0, 2*pi)
   float phidif = sphi - hphi;
   if (phidif < 0.)
     phidif += 2. * M_PI;  // into range [0, 2pi)
   if (phidif > M_PI)
     phidif -= 2. * M_PI;  // into range (-pi, pi]
 
   float dRPhi = fabs(phidif) * hp.perp();
   LogDebug("CSC") << "    is hit at phi_h= " << hphi << " near segment phi_seg= " << sphi << "? is " << dRPhi << "<"
                   << dRPhiFineMax << " ? "
                   << " and is |" << phidif << "|<" << dPhiFineMax << " ?";
 
   return ((dRPhi < dRPhiFineMax) && (fabs(phidif) < dPhiFineMax)) ? true : false;  // +v
 }
 
 bool CSCSegAlgoTC::hasHitOnLayer(int layer) const {
   // Is there is already a hit on this layer?
   ChamberHitContainerCIt it;
 
   for (it = proto_segment.begin(); it != proto_segment.end(); it++)
     if ((*it)->cscDetId().layer() == layer)
       return true;
 
   return false;
 }
 
 void CSCSegAlgoTC::dumpHits(const ChamberHitContainer& rechits) const {
   // Dump positions of RecHit's in each CSCChamber
   ChamberHitContainerCIt it;
 
   for (it = rechits.begin(); it != rechits.end(); it++) {
     const CSCLayer* l1 = theChamber->layer((*it)->cscDetId().layer());
     GlobalPoint gp1 = l1->toGlobal((*it)->localPosition());
 
     LogDebug("CSC") << "Global pos.: " << gp1 << ", phi: " << gp1.phi()
                     << ". Local position: " << (*it)->localPosition() << ", phi: " << (*it)->localPosition().phi()
                     << ". Layer: " << (*it)->cscDetId().layer() << "\n";
   }
 }
 
 bool CSCSegAlgoTC::isSegmentGood(std::vector<CSCSegFit*>::iterator seg,
                                  const ChamberHitContainer& rechitsInChamber,
                                  BoolContainer& used) const {
   // Apply any selection cuts to segment
 
   // 1) Require a minimum no. of hits
   //   (@@ THESE VALUES SHOULD BECOME PARAMETERS?)
 
   // 2) Ensure no hits on segment are already assigned to another segment
   //    (typically of higher quality)
 
   size_t iadd = (rechitsInChamber.size() > 20) ? 1 : 0;
 
   size_t nhits = (*seg)->nhits();
 
   if (nhits < 3 + iadd)
     return false;
 
   // Additional part of alternative segment selection scheme: reject
   // segments with a chi2 probability of less than chi2ndfProbMin. Relies on list
   // being sorted with "SegmentSorting == 2", that is first by nrechits and then
   // by chi2prob in subgroups of same no. of rechits.
 
   if (SegmentSorting == 2) {
     double chi2t = (*seg)->chi2();
     double ndoft = 2 * nhits - 4;
     if (chi2t > 0 && ndoft > 0) {
       if (ChiSquaredProbability(chi2t, ndoft) < chi2ndfProbMin) {
         return false;
       }
     } else {
       return false;
     }
   }
 
   ChamberHitContainer hits_ = (*seg)->hits();
 
   for (size_t ish = 0; ish < nhits; ++ish) {
     ChamberHitContainerCIt ib = rechitsInChamber.begin();
 
     for (ChamberHitContainerCIt ic = ib; ic != rechitsInChamber.end(); ++ic) {
       if ((hits_[ish] == (*ic)) && used[ic - ib])
         return false;
     }
   }
 
   return true;
 }
 
 void CSCSegAlgoTC::flagHitsAsUsed(std::vector<CSCSegFit*>::iterator seg,
                                   const ChamberHitContainer& rechitsInChamber,
                                   BoolContainer& used) const {
   // Flag hits on segment as used
 
   ChamberHitContainerCIt ib = rechitsInChamber.begin();
   ChamberHitContainer hits = (*seg)->hits();
 
   for (size_t ish = 0; ish < hits.size(); ++ish) {
     for (ChamberHitContainerCIt iu = ib; iu != rechitsInChamber.end(); ++iu)
       if (hits[ish] == (*iu))
         used[iu - ib] = true;
   }
 }
 
 void CSCSegAlgoTC::pruneTheSegments(const ChamberHitContainer& rechitsInChamber) {
   // Sort the segment store according to segment 'quality' (chi2/#hits ?) and
   // remove any segments which contain hits assigned to higher-quality segments.
 
   if (candidates.empty())
     return;
 
   // Initialize flags that a given hit has been allocated to a segment
   BoolContainer used(rechitsInChamber.size(), false);
 
   // Sort by chi2/#hits
   segmentSort();
 
   // Select best quality segments, requiring hits are assigned to just one segment
   // Want to erase the bad segments, so the iterator must be incremented
   // inside the loop, and only when the erase is not called
 
   std::vector<CSCSegFit*>::iterator is;
 
   for (is = candidates.begin(); is != candidates.end();) {
     bool goodSegment = isSegmentGood(is, rechitsInChamber, used);
 
     if (goodSegment) {
       LogDebug("CSC") << "Accepting segment: ";
       flagHitsAsUsed(is, rechitsInChamber, used);
       ++is;
     } else {
       LogDebug("CSC") << "Rejecting segment: ";
       delete *is;                 // delete the CSCSegFit*
       is = candidates.erase(is);  // erase the element in container
     }
   }
 }
 
 void CSCSegAlgoTC::segmentSort() {
   // The segment collection is sorted according to e.g. chi2/#hits
 
   for (size_t i = 0; i < candidates.size() - 1; ++i) {
     for (size_t j = i + 1; j < candidates.size(); ++j) {
       size_t ni = (candidates[i]->hits()).size();
       size_t nj = (candidates[j]->hits()).size();
 
       // Sort criterion: first sort by no. of rechits, then in groups of rechits by chi2prob
       if (SegmentSorting == 2) {
         if (nj > ni) {  // sort by no. of rechits
           CSCSegFit* temp = candidates[j];
           candidates[j] = candidates[i];
           candidates[i] = temp;
         }
         // sort by chi2 probability in subgroups with equal nr of rechits
         //  if(chi2s[i] != 0. && 2*n2-4 > 0 ) {
         if (candidates[i]->chi2() > 0 && candidates[i]->ndof() > 0) {
           if (nj == ni && (ChiSquaredProbability(candidates[i]->chi2(), (double)(candidates[i]->ndof())) <
                            ChiSquaredProbability(candidates[j]->chi2(), (double)(candidates[j]->ndof())))) {
             CSCSegFit* temp = candidates[j];
             candidates[j] = candidates[i];
             candidates[i] = temp;
           }
         }
       } else if (SegmentSorting == 1) {
         if ((candidates[i]->chi2() / ni) > (candidates[j]->chi2() / nj)) {
           CSCSegFit* temp = candidates[j];
           candidates[j] = candidates[i];
           candidates[i] = temp;
         }
       } else {
         LogDebug("CSC") << "No valid segment sorting specified. Algorithm misconfigured! \n";
       }
     }
   }
 }
 
 void CSCSegAlgoTC::dumpSegment(const CSCSegment& seg) const {
   edm::LogVerbatim("CSCSegment") << "CSCSegment in " << theChamber->id() << "\nlocal position = " << seg.localPosition()
                                  << "\nerror = " << seg.localPositionError()
                                  << "\nlocal direction = " << seg.localDirection()
                                  << "\nerror =" << seg.localDirectionError() << "\ncovariance matrix"
                                  << seg.parametersError() << "chi2/ndf = " << seg.chi2() << "/"
                                  << seg.degreesOfFreedom() << "\n#rechits = " << seg.specificRecHits().size()
                                  << "\ntime = " << seg.time();
 }

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