HemisphereAlgo.cc

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#include "PhysicsTools/PatAlgos/interface/HemisphereAlgo.h"

#include "FWCore/MessageLogger/interface/MessageLogger.h"

#include "DataFormats/Math/interface/deltaPhi.h"
#include "DataFormats/Math/interface/deltaR.h"

using namespace std;
using std::vector;

HemisphereAlgo::HemisphereAlgo(const std::vector<reco::CandidatePtr>& componentPtr_,
                               const int seed_method,
                               const int hemisphere_association_method)
    : Object(componentPtr_),
      Object_Group(),
      Axis1(),
      Axis2(),
      seed_meth(seed_method),
      hemi_meth(hemisphere_association_method),
      status(0) {
  for (int i = 0; i < (int)Object.size(); i++) {
    Object_Noseed.push_back(0);
  }
}

vector<float> HemisphereAlgo::getAxis1() {
  if (status != 1) {
    this->reconstruct();
  }
  return Axis1;
}
vector<float> HemisphereAlgo::getAxis2() {
  if (status != 1) {
    this->reconstruct();
  }
  return Axis2;
}

vector<int> HemisphereAlgo::getGrouping() {
  if (status != 1) {
    this->reconstruct();
  }
  return Object_Group;
}

int HemisphereAlgo::reconstruct() {
  int vsize = (int)Object.size();

  LogDebug("HemisphereAlgo") << " HemisphereAlgo method ";

  Object_Group.clear();
  Axis1.clear();
  Axis2.clear();

  for (int j = 0; j < vsize; j++) {
    Object_Group.push_back(0);
  }

  for (int j = 0; j < 5; j++) {
    Axis1.push_back(0);
    Axis2.push_back(0);
  }

  for (int i = 0; i < vsize; i++) {
    if ((*(Object)[i]).p() > (*Object[i]).energy() + 0.001) {
      edm::LogWarning("HemisphereAlgo") << "Object " << i << " has E = " << (*Object[i]).energy()
                                        << " less than P = " << (*Object[i]).p();
    }
  }

  LogDebug("HemisphereAlgo") << " Seeding method = " << seed_meth;
  int I_Max = -1;
  int J_Max = -1;

  if (seed_meth == 1) {
    float P_Max = 0.;
    float DeltaRP_Max = 0.;

    // take highest momentum object as first axis
    for (int i = 0; i < vsize; i++) {
      Object_Group[i] = 0;
      if (Object_Noseed[i] == 0 && P_Max < (*Object[i]).p()) {
        P_Max = (*Object[i]).p();
        I_Max = i;
      }
    }

    Axis1[0] = (*Object[I_Max]).px() / (*Object[I_Max]).p();
    Axis1[1] = (*Object[I_Max]).py() / (*Object[I_Max]).p();
    Axis1[2] = (*Object[I_Max]).pz() / (*Object[I_Max]).p();
    Axis1[3] = (*Object[I_Max]).p();
    Axis1[4] = (*Object[I_Max]).energy();

    // take as second axis
    for (int i = 0; i < vsize; i++) {
      float DeltaR = deltaR((*Object[i]).eta(), (*Object[i]).phi(), (*Object[I_Max]).eta(), (*Object[I_Max]).phi());

      if (Object_Noseed[i] == 0 && DeltaR > 0.5) {
        float DeltaRP = DeltaR * (*Object[i]).p();
        if (DeltaRP > DeltaRP_Max) {
          DeltaRP_Max = DeltaRP;
          J_Max = i;
        }
      }
    }

    if (J_Max >= 0) {
      Axis2[0] = (*Object[J_Max]).px() / (*Object[J_Max]).p();
      Axis2[1] = (*Object[J_Max]).py() / (*Object[J_Max]).p();
      Axis2[2] = (*Object[J_Max]).pz() / (*Object[J_Max]).p();
      Axis2[3] = (*Object[J_Max]).p();
      Axis2[4] = (*Object[J_Max]).energy();

    } else {
      return 0;
    }
    LogDebug("HemisphereAlgo") << " Axis 1 is Object = " << I_Max;
    LogDebug("HemisphereAlgo") << " Axis 2 is Object = " << J_Max;

  } else if ((seed_meth == 2) | (seed_meth == 3)) {
    float Mass_Max = 0.;
    float InvariantMass = 0.;

    // maximize the invariant mass of two objects
    for (int i = 0; i < vsize; i++) {
      Object_Group[i] = 0;
      if (Object_Noseed[i] == 0) {
        for (int j = i + 1; j < vsize; j++) {
          if (Object_Noseed[j] == 0) {
            // either the invariant mass
            if (seed_meth == 2) {
              InvariantMass =
                  ((*Object[i]).energy() + (*Object[j]).energy()) * ((*Object[i]).energy() + (*Object[j]).energy()) -
                  ((*Object[i]).px() + (*Object[j]).px()) * ((*Object[i]).px() + (*Object[j]).px()) -
                  ((*Object[i]).py() + (*Object[j]).py()) * ((*Object[i]).py() + (*Object[j]).py()) -
                  ((*Object[i]).pz() + (*Object[j]).pz()) * ((*Object[i]).pz() + (*Object[j]).pz());
            }
            // or the transverse mass
            else if (seed_meth == 3) {
              float pti = sqrt((*Object[i]).px() * (*Object[i]).px() + (*Object[i]).py() * (*Object[i]).py());
              float ptj = sqrt((*Object[j]).px() * (*Object[j]).px() + (*Object[j]).py() * (*Object[j]).py());
              InvariantMass =
                  2. * (pti * ptj - (*Object[i]).px() * (*Object[j]).px() - (*Object[i]).py() * (*Object[j]).py());
            }
            if (Mass_Max < InvariantMass) {
              Mass_Max = InvariantMass;
              I_Max = i;
              J_Max = j;
            }
          }
        }
      }
    }

    if (J_Max > 0) {
      Axis1[0] = (*Object[I_Max]).px() / (*Object[I_Max]).p();
      Axis1[1] = (*Object[I_Max]).py() / (*Object[I_Max]).p();
      Axis1[2] = (*Object[I_Max]).pz() / (*Object[I_Max]).p();

      Axis1[3] = (*Object[I_Max]).p();
      Axis1[4] = (*Object[I_Max]).energy();

      Axis2[0] = (*Object[J_Max]).px() / (*Object[J_Max]).p();
      Axis2[1] = (*Object[J_Max]).py() / (*Object[J_Max]).p();
      Axis2[2] = (*Object[J_Max]).pz() / (*Object[J_Max]).p();

      Axis2[3] = (*Object[J_Max]).p();
      Axis2[4] = (*Object[J_Max]).energy();

    } else {
      return 0;
    }
    LogDebug("HemisphereAlgo") << " Axis 1 is Object = " << I_Max;
    LogDebug("HemisphereAlgo") << " Axis 2 is Object = " << J_Max;

  } else {
    throw cms::Exception("Configuration") << "Please give a valid seeding method!";
  }

  // seeding done
  // now do the hemisphere association

  LogDebug("HemisphereAlgo") << " Association method = " << hemi_meth;

  int numLoop = 0;
  bool I_Move = true;

  while (I_Move && (numLoop < 100)) {
    I_Move = false;
    numLoop++;
    LogDebug("HemisphereAlgo") << " Iteration = " << numLoop;

    float Sum1_Px = 0.;
    float Sum1_Py = 0.;
    float Sum1_Pz = 0.;
    float Sum1_E = 0.;
    float Sum2_Px = 0.;
    float Sum2_Py = 0.;
    float Sum2_Pz = 0.;
    float Sum2_E = 0.;

    if (hemi_meth == 1) {
      for (int i = 0; i < vsize; i++) {
        float P_Long1 = (*Object[i]).px() * Axis1[0] + (*Object[i]).py() * Axis1[1] + (*Object[i]).pz() * Axis1[2];
        float P_Long2 = (*Object[i]).px() * Axis2[0] + (*Object[i]).py() * Axis2[1] + (*Object[i]).pz() * Axis2[2];
        if (P_Long1 >= P_Long2) {
          if (Object_Group[i] != 1) {
            I_Move = true;
          }
          Object_Group[i] = 1;
          Sum1_Px += (*Object[i]).px();
          Sum1_Py += (*Object[i]).py();
          Sum1_Pz += (*Object[i]).pz();
          Sum1_E += (*Object[i]).energy();
        } else {
          if (Object_Group[i] != 2) {
            I_Move = true;
          }
          Object_Group[i] = 2;
          Sum2_Px += (*Object[i]).px();
          Sum2_Py += (*Object[i]).py();
          Sum2_Pz += (*Object[i]).pz();
          Sum2_E += (*Object[i]).energy();
        }
      }

    } else if (hemi_meth == 2 || hemi_meth == 3) {
      for (int i = 0; i < vsize; i++) {
        if (i == I_Max) {
          Object_Group[i] = 1;
          Sum1_Px += (*Object[i]).px();
          Sum1_Py += (*Object[i]).py();
          Sum1_Pz += (*Object[i]).pz();
          Sum1_E += (*Object[i]).energy();
        } else if (i == J_Max) {
          Object_Group[i] = 2;
          Sum2_Px += (*Object[i]).px();
          Sum2_Py += (*Object[i]).py();
          Sum2_Pz += (*Object[i]).pz();
          Sum2_E += (*Object[i]).energy();
        } else {
          if (!I_Move) {
            float NewAxis1_Px = Axis1[0] * Axis1[3];
            float NewAxis1_Py = Axis1[1] * Axis1[3];
            float NewAxis1_Pz = Axis1[2] * Axis1[3];
            float NewAxis1_E = Axis1[4];

            float NewAxis2_Px = Axis2[0] * Axis2[3];
            float NewAxis2_Py = Axis2[1] * Axis2[3];
            float NewAxis2_Pz = Axis2[2] * Axis2[3];
            float NewAxis2_E = Axis2[4];

            if (Object_Group[i] == 1) {
              NewAxis1_Px = NewAxis1_Px - (*Object[i]).px();
              NewAxis1_Py = NewAxis1_Py - (*Object[i]).py();
              NewAxis1_Pz = NewAxis1_Pz - (*Object[i]).pz();
              NewAxis1_E = NewAxis1_E - (*Object[i]).energy();

            } else if (Object_Group[i] == 2) {
              NewAxis2_Px = NewAxis2_Px - (*Object[i]).px();
              NewAxis2_Py = NewAxis2_Py - (*Object[i]).py();
              NewAxis2_Pz = NewAxis2_Pz - (*Object[i]).pz();
              NewAxis2_E = NewAxis2_E - (*Object[i]).energy();
            }

            float mass1 =
                NewAxis1_E -
                (((*Object[i]).px() * NewAxis1_Px + (*Object[i]).py() * NewAxis1_Py + (*Object[i]).pz() * NewAxis1_Pz) /
                 (*Object[i]).p());

            float mass2 =
                NewAxis2_E -
                (((*Object[i]).px() * NewAxis2_Px + (*Object[i]).py() * NewAxis2_Py + (*Object[i]).pz() * NewAxis2_Pz) /
                 (*Object[i]).p());

            if (hemi_meth == 3) {
              mass1 *= NewAxis1_E / ((NewAxis1_E + (*Object[i]).energy()) * (NewAxis1_E + (*Object[i]).energy()));

              mass2 *= NewAxis2_E / ((NewAxis2_E + (*Object[i]).energy()) * (NewAxis2_E + (*Object[i]).energy()));
            }

            if (mass1 < mass2) {
              if (Object_Group[i] != 1) {
                I_Move = true;
              }
              Object_Group[i] = 1;

              Sum1_Px += (*Object[i]).px();
              Sum1_Py += (*Object[i]).py();
              Sum1_Pz += (*Object[i]).pz();
              Sum1_E += (*Object[i]).energy();
            } else {
              if (Object_Group[i] != 2) {
                I_Move = true;
              }
              Object_Group[i] = 2;
              Sum2_Px += (*Object[i]).px();
              Sum2_Py += (*Object[i]).py();
              Sum2_Pz += (*Object[i]).pz();
              Sum2_E += (*Object[i]).energy();
            }

          } else {
            if (Object_Group[i] == 1) {
              Sum1_Px += (*Object[i]).px();
              Sum1_Py += (*Object[i]).py();
              Sum1_Pz += (*Object[i]).pz();
              Sum1_E += (*Object[i]).energy();
            }
            if (Object_Group[i] == 2) {
              Sum2_Px += (*Object[i]).px();
              Sum2_Py += (*Object[i]).py();
              Sum2_Pz += (*Object[i]).pz();
              Sum2_E += (*Object[i]).energy();
            }
          }
        }
      }
    } else {
      throw cms::Exception("Configuration") << "Please give a valid hemisphere association method!";
    }

    // recomputing the axes

    Axis1[3] = sqrt(Sum1_Px * Sum1_Px + Sum1_Py * Sum1_Py + Sum1_Pz * Sum1_Pz);
    if (Axis1[3] < 0.0001) {
      edm::LogWarning("HemisphereAlgo") << "ZERO objects in group 1! ";
    } else {
      Axis1[0] = Sum1_Px / Axis1[3];
      Axis1[1] = Sum1_Py / Axis1[3];
      Axis1[2] = Sum1_Pz / Axis1[3];
      Axis1[4] = Sum1_E;
    }

    Axis2[3] = sqrt(Sum2_Px * Sum2_Px + Sum2_Py * Sum2_Py + Sum2_Pz * Sum2_Pz);
    if (Axis2[3] < 0.0001) {
      edm::LogWarning("HemisphereAlgo") << "ZERO objects in group 2!";
    } else {
      Axis2[0] = Sum2_Px / Axis2[3];
      Axis2[1] = Sum2_Py / Axis2[3];
      Axis2[2] = Sum2_Pz / Axis2[3];
      Axis2[4] = Sum2_E;
    }

    LogDebug("HemisphereAlgo") << " Grouping = ";
    for (int i = 0; i < vsize; i++) {
      LogTrace("HemisphereAlgo") << "  " << Object_Group[i];
    }
    LogTrace("HemisphereAlgo") << std::endl;
  }

  status = 1;
  return 1;
}