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

 /**
  * \file CSCSegAlgoSK.cc
  *
  */
 
 #include "CSCSegAlgoSK.h"
 #include "CSCSegFit.h"
 #include "Geometry/CSCGeometry/interface/CSCLayer.h"
 #include "DataFormats/GeometryVector/interface/GlobalPoint.h"
 
 #include "FWCore/ParameterSet/interface/ParameterSet.h"
 #include "FWCore/MessageLogger/interface/MessageLogger.h"
 
 #include <algorithm>
 #include <cmath>
 #include <iostream>
 #include <string>
 
 CSCSegAlgoSK::CSCSegAlgoSK(const edm::ParameterSet& ps)
     : CSCSegmentAlgorithm(ps), myName("CSCSegAlgoSK"), sfit_(nullptr) {
   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");
   wideSeg = ps.getParameter<double>("wideSeg");
   minLayersApart = ps.getParameter<int>("minLayersApart");
 
   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'
                   << "wideSeg      = " << wideSeg << '\n'
                   << "minLayersApart = " << minLayersApart << std::endl;
 }
 
 std::vector<CSCSegment> CSCSegAlgoSK::run(const CSCChamber* aChamber, const ChamberHitContainer& rechits) {
   theChamber = aChamber;
   return buildSegments(rechits);
 }
 
 std::vector<CSCSegment> CSCSegAlgoSK::buildSegments(const ChamberHitContainer& urechits) {
   LogDebug("CSC") << "*********************************************";
   LogDebug("CSC") << "Start segment building in the new chamber: " << theChamber->specs()->chamberTypeName();
   LogDebug("CSC") << "*********************************************";
 
   ChamberHitContainer rechits = urechits;
   LayerIndex layerIndex(rechits.size());
 
   for (unsigned int i = 0; i < rechits.size(); i++) {
     layerIndex[i] = rechits[i]->cscDetId().layer();
   }
 
   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());
     }
   }
 
   //  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.
   // BUT... once a hit has been assigned to a segment, we don't consider
   // it again.
 
   // 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.
 
   // Initialize flags that a given hit has been allocated to a segment
   BoolContainer used(rechits.size(), false);
 
   // Define buffer for segments we build
   std::vector<CSCSegment> segments;
 
   // This is going to point to fits to hits, and its content will be used to create a CSCSegment
   sfit_ = nullptr;
 
   ChamberHitContainerCIt ib = rechits.begin();
   ChamberHitContainerCIt ie = rechits.end();
 
   // Possibly allow 2 passes, second widening scale factor for cuts
   windowScale = 1.;  // scale factor for cuts
 
   int npass = (wideSeg > 1.) ? 2 : 1;
 
   for (int ipass = 0; ipass < npass; ++ipass) {
     for (ChamberHitContainerCIt i1 = ib; i1 != ie; ++i1) {
       bool segok = false;
       if (used[i1 - ib])
         continue;
 
       int layer1 = layerIndex[i1 - ib];  //(*i1)->cscDetId().layer();
       const CSCRecHit2D* h1 = *i1;
 
       for (ChamberHitContainerCIt i2 = ie - 1; i2 != i1; --i2) {
         if (used[i2 - ib])
           continue;
 
         int layer2 = layerIndex[i2 - ib];  //(*i2)->cscDetId().layer();
 
         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(layer1);
           GlobalPoint gp1 = l1->toGlobal(h1->localPosition());
           const CSCLayer* l2 = theChamber->layer(layer2);
           GlobalPoint gp2 = l2->toGlobal(h2->localPosition());
           LogDebug("CSC") << "start new segment from hits "
                           << "h1: " << gp1 << " - h2: " << gp2 << "\n";
 
           //@@ TRY ADDING A HIT - AND FIT
           if (!addHit(h1, layer1)) {
             LogDebug("CSC") << "  failed to add hit h1\n";
             continue;
           }
 
           if (!addHit(h2, layer2)) {
             LogDebug("CSC") << "  failed to add hit h2\n";
             continue;
           }
 
           // Can only add hits if already have a segment
           if (sfit_)
             tryAddingHitsToSegment(rechits, used, layerIndex, i1, i2);
 
           // Check no. of hits on segment, and if enough flag them as used
           // and store the segment
           segok = isSegmentGood(rechits);
           if (segok) {
             flagHitsAsUsed(rechits, used);
             // Copy the proto_segment and its properties inside a CSCSegment.
             // Then fill the segment vector..
 
             if (proto_segment.empty()) {
               LogDebug("CSC") << "No segment has been found !!!\n";
             } else {
               // Create an actual CSCSegment - retrieve all info from the fit
               CSCSegment temp(
                   sfit_->hits(), sfit_->intercept(), sfit_->localdir(), sfit_->covarianceMatrix(), sfit_->chi2());
               delete sfit_;
               sfit_ = nullptr;
               LogDebug("CSC") << "Found a segment !!!\n";
               if (debugInfo)
                 dumpSegment(temp);
               segments.push_back(temp);
             }
           }
         }  //   h1 & h2 close
 
         if (segok)
           break;
       }  //  i2
     }  //  i1
 
     if (segments.size() > 1)
       break;  // only change window if no segments found
 
     // Increase cut windows by factor of wideSeg
     windowScale = wideSeg;
 
   }  //  ipass
 
   // Give the segments to the CSCChamber
   return segments;
 }
 
 void CSCSegAlgoSK::tryAddingHitsToSegment(const ChamberHitContainer& rechits,
                                           const BoolContainer& used,
                                           const LayerIndex& layerIndex,
                                           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 || used[i - ib])
       continue;
 
     int layer = layerIndex[i - ib];
     const CSCRecHit2D* h = *i;
     if (isHitNearSegment(h)) {
       GlobalPoint gp1 = theChamber->layer(layer)->toGlobal(h->localPosition());
       LogDebug("CSC") << "    hit at global " << gp1 << " is near segment\n.";
 
       // Don't consider alternate hits on layers holding the two starting points
       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 CSCSegAlgoSK::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 * windowScale)) ? true : false;  // +v
 }
 
 bool CSCSegAlgoSK::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 * windowScale)) ? true : false;  // +v
 }
 
 bool CSCSegAlgoSK::isHitNearSegment(const CSCRecHit2D* h) const {
   // Is hit near segment?
   // Requires deltaphi and rxy*deltaphi within ranges specified
   // in parameter set, 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 * windowScale << " ? "
                   << " and is |" << phidif << "|<" << dPhiFineMax * windowScale << " ?";
 
   return ((dRPhi < dRPhiFineMax * windowScale) && (fabs(phidif) < dPhiFineMax * windowScale)) ? true : false;  // +v
 }
 
 float CSCSegAlgoSK::phiAtZ(float z) const {
   if (!sfit_) {
     edm::LogVerbatim("CSCSegment") << "[CSCSegAlgoSK::phiAtZ] Segment fit undefined";
     return 0.;
   }
 
   // Returns a phi in [ 0, 2*pi )
   const CSCLayer* l1 = theChamber->layer((*(proto_segment.begin()))->cscDetId().layer());
   GlobalPoint gp = l1->toGlobal(sfit_->intercept());
   GlobalVector gv = l1->toGlobal(sfit_->localdir());
 
   LogTrace("CSCSegment") << "[CSCSegAlgoSK::phiAtZ] Global intercept = " << gp << ", direction = " << gv;
 
   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 CSCSegAlgoSK::dumpHits(const ChamberHitContainer& rechits) const {
   // Dump positions of RecHit's in each CSCChamber
   ChamberHitContainerCIt it;
   edm::LogInfo("CSCSegment") << "CSCChamber rechit dump.\n";
   for (it = rechits.begin(); it != rechits.end(); it++) {
     const CSCLayer* l1 = theChamber->layer((*it)->cscDetId().layer());
     GlobalPoint gp1 = l1->toGlobal((*it)->localPosition());
 
     edm::LogInfo("CSCSegment") << "Global pos.: " << gp1 << ", phi: " << gp1.phi()
                                << ". Local position: " << (*it)->localPosition()
                                << ", phi: " << (*it)->localPosition().phi() << ". Layer: " << (*it)->cscDetId().layer()
                                << "\n";
   }
 }
 
 bool CSCSegAlgoSK::isSegmentGood(const ChamberHitContainer& rechitsInChamber) const {
   // If the chamber has 20 hits or fewer, require at least 3 hits on segment
   // If the chamber has >20 hits require at least 4 hits
 
   bool ok = false;
 
   unsigned int iadd = (rechitsInChamber.size() > 20) ? 1 : 0;
 
   if (windowScale > 1.)
     iadd = 1;
 
   if (proto_segment.size() >= 3 + iadd)
     ok = true;
 
   return ok;
 }
 
 void CSCSegAlgoSK::flagHitsAsUsed(const ChamberHitContainer& rechitsInChamber, BoolContainer& used) const {
   // Flag hits on segment as used
   ChamberHitContainerCIt ib = rechitsInChamber.begin();
   ChamberHitContainerCIt hi, iu;
 
   for (hi = proto_segment.begin(); hi != proto_segment.end(); ++hi) {
     for (iu = ib; iu != rechitsInChamber.end(); ++iu) {
       if (*hi == *iu)
         used[iu - ib] = true;
     }
   }
 }
 
 bool CSCSegAlgoSK::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.
 
   ChamberHitContainer::const_iterator it;
 
   for (it = proto_segment.begin(); it != proto_segment.end(); it++)
     if (((*it)->cscDetId().layer() == layer) && (aHit != (*it)))
       return false;
 
   proto_segment.push_back(aHit);
 
   // make a fit
   updateParameters();
   return true;
 }
 
 void CSCSegAlgoSK::updateParameters(void) {
   // Delete input CSCSegFit, create a new one and make the fit
   delete sfit_;
   sfit_ = new CSCSegFit(theChamber, proto_segment);
   sfit_->fit();
 }
 
 bool CSCSegAlgoSK::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;
 }
 
 bool CSCSegAlgoSK::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 CSCSegAlgoSK::compareProtoSegment(const CSCRecHit2D* h, int layer) {
   // Copy the input CSCSegFit
   CSCSegFit* oldfit = new CSCSegFit(*sfit_);
 
   // May create a new fit
   bool ok = replaceHit(h, layer);
 
   if (ok) {
     LogDebug("CSCSegment") << "    hit in same layer as a hit on segment; try replacing old one..."
                            << " chi2 new: " << sfit_->chi2() << " old: " << oldfit->chi2() << "\n";
   }
 
   if ((sfit_->chi2() < oldfit->chi2()) && ok) {
     LogDebug("CSC") << "    segment with replaced hit is better.\n";
     delete oldfit;  // new fit is better
   } else {
     // keep original fit
     delete sfit_;    // now the new fit
     sfit_ = oldfit;  // reset to the original input fit
   }
 }
 
 void CSCSegAlgoSK::increaseProtoSegment(const CSCRecHit2D* h, int layer) {
   // Copy input fit
   CSCSegFit* oldfit = new CSCSegFit(*sfit_);
 
   // Creates a new fit
   bool ok = addHit(h, layer);
 
   if (ok) {
     LogDebug("CSCSegment") << "    hit in new layer: added to segment, new chi2: " << sfit_->chi2() << "\n";
   }
 
   //  int ndf = 2*proto_segment.size() - 4;
 
   //@@ TEST ON ndof<=0 IS JUST TO ACCEPT nhits=2 CASE??
   if (ok && ((sfit_->ndof() <= 0) || (sfit_->chi2() / sfit_->ndof() < chi2Max))) {
     LogDebug("CSCSegment") << "    segment with added hit is good.\n";
     delete oldfit;  // new fit is better
   } else {
     // reset to original fit
     delete sfit_;
     sfit_ = oldfit;
   }
 }
 
 void CSCSegAlgoSK::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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