functions.cxx

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#include "eicsmear/functions.h"

#include <cmath>
#include <fstream>
#include <set>
#include <sstream>
#include <string>

#include <TLorentzVector.h>
#include <TMath.h>
#include <TParticlePDG.h>
#include <TVector2.h>
#include <TVector3.h>

#include "eicsmear/erhic/EventMC.h"
#include "eicsmear/erhic/ParticleMC.h"

char getFirstNonBlank(const std::string& line) {
  char first('\0');  // NULL character by default
                      // Find the index first non-blank character.
  size_t index = line.find_first_not_of(" \t");

  if (index != std::string::npos) {
    first = line.at(index);
  }  // if

  return first;
}

double
computeHermesPhiH(const TLorentzVector& hadronInPrf,
                  const TLorentzVector& leptonInPrf,
                  const TLorentzVector& photonInPrf) {
  const TVector3& q = photonInPrf.Vect();
  const TVector3& k = leptonInPrf.Vect();
  const TVector3& Ph = hadronInPrf.Vect();
  const TVector3& qCrossK = q.Cross(k);
  const TVector3& qCrossPh = q.Cross(Ph);
  // Used to determine spin direction:
  double qCrossKDotPh = qCrossK.Dot(Ph);
  if (::fabs(qCrossKDotPh) < 1.0e-5) return -999.0;

  // First get phi in the range [0,pi]:
  double phi = TMath::ACos(qCrossK.Dot(qCrossPh)
                           / qCrossK.Mag()
                           / qCrossPh.Mag());

  // Handle spin direction to get result in range [-pi,pi] by
  // scaling by [-1,+1], depending on hemisphere.
  phi *= qCrossKDotPh / ::fabs(qCrossKDotPh);

  return TVector2::Phi_0_2pi(phi);
}

//
// class EventToDot.
//

struct Pair {
  int a;
  int b;
  Pair(int x, int y) : a(x), b(y) { }
  // Less-than operator required for entry in sorted container.
  bool operator<(const Pair& other) const {
    if (other.a == a) return b < other.b;
    return a < other.a;
  }
};


void EventToDot::Generate(const erhic::EventMC& event,
                          const std::string& name) const {
  std::ofstream file(name.c_str());
  std::ostringstream oss;

  file << "digraph G {" << std::endl;
  oss << "   label = \"Event " << event.GetN() << "\"';";
  file << oss.str() << std::endl;

  std::set<Pair> pairs;

  // Keep track of which particles we use in the diagram
  // so we can set node attributes at the end.
  // Use a set to avoid worrying about adding duplicates.
  std::set<const erhic::ParticleMC*> used;

  // Loop over all tracks in the event and accumulate indices giving
  // parent/child relationships.
  // We look from parent->child and child->parent because they
  // aren't always fully indexed both ways.
  for (unsigned i(0); i < event.GetNTracks(); ++i) {
    // Check parent of particle
    const erhic::ParticleMC* parent = event.GetTrack(i)->GetParent();
    if (parent) {
      pairs.insert(Pair(parent->GetIndex(), event.GetTrack(i)->GetIndex()));
      used.insert(parent);
      used.insert(event.GetTrack(i));
    }  // if
    // Check children of particle
    for (unsigned j(0); j < event.GetTrack(i)->GetNChildren(); ++j) {
      pairs.insert(Pair(event.GetTrack(i)->GetIndex(),
                        event.GetTrack(i)->GetChild(j)->GetIndex()));
      used.insert(event.GetTrack(i));
      used.insert(event.GetTrack(i)->GetChild(j));
    }  // for
  }  // for
  // Insert relationships between particles.
  for (std::set<Pair>::const_iterator i = pairs.begin();
      i != pairs.end();
      ++i) {
    const erhic::ParticleMC* a = event.GetTrack(i->a - 1);
    const erhic::ParticleMC* b = event.GetTrack(i->b - 1);
    oss.str("");
    oss << "   " << a->GetIndex() << " -> " <<
    b->GetIndex();
    file << oss.str() << std::endl;
  }  // for
  file << "#   Node attributes" << std::endl;
  // Apply labels, formatting to used particles.
  for (std::set<const erhic::ParticleMC*>::const_iterator i = used.begin();
      i != used.end();
      ++i) {
    std::string shape("ellipse");
    if ((*i)->GetStatus() == 1) {
      shape = "box";
    }  // if
    if ((*i)->GetIndex() < 3) {
      shape = "diamond";
    }  // if
    oss.str("");
    oss << "   " << (*i)->GetIndex() << " [label=\"" << (*i)->GetIndex() << " ";
    if ((*i)->Id().Info()) {
      oss << (*i)->Id().Info()->GetName();
    } else {
      oss << "unknown PDG " << (*i)->Id().Code();
    }  // if
    oss << "\", shape=" << shape << "];";
    file << oss.str() << std::endl;
  }  // for
  file << "}";
}