PunchThroughPDFCreator.cxx

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/*
  Copyright (C) 2002-2024 CERN for the benefit of the ATLAS collaboration
*/

// PunchThroughPDFCreator.cxx, (c) ATLAS Detector software
 
// class header
#include "PunchThroughPDFCreator.h"
 
// std
#include <algorithm>
 
// Random number generators
#include "CLHEP/Random/RandFlat.h"
 
// ROOT
#include "TH1F.h"
 
PunchThroughPDFCreator::~PunchThroughPDFCreator() {
  for(auto & each_outter : m_energy_eta_hists1D) {
    for(auto & each_inner : each_outter.second) {
      delete each_inner.second;
    }
  }
}
 
void PunchThroughPDFCreator::addToEnergyEtaHist1DMap(int energy, int etaMin, TH1 *hist) {
  // Make a local copy
  TH1* localHist = (TH1*) hist->Clone();
  localHist->SetDirectory(0);
 
  if(m_energy_eta_hists1D.find(energy) != m_energy_eta_hists1D.end()){ //if energy entry exists, insert into inner eta map
    (m_energy_eta_hists1D.find(energy)->second).insert(std::make_pair(etaMin, localHist));
  }
  else{ //if energy entry does not exist create new full energy entry
    std::map< int, TH1*> inner;
    inner.insert(std::make_pair(etaMin, localHist));
    m_energy_eta_hists1D.insert(std::make_pair(energy, inner));
  }
}
 
double PunchThroughPDFCreator::getRand(CLHEP::HepRandomEngine* rndmEngine, const std::vector<int>& inputParameters) const
{
 
    //define variable to return from getRand call, should never return zero
    float randomHist = 0.;
 
    if( m_energy_eta_hists1D.find(inputParameters.at(0)) == m_energy_eta_hists1D.end()) {
        //this should never be reached
        return 0.;
    }
 
    const std::map< int, TH1*>& etaMin_hists = m_energy_eta_hists1D.at(inputParameters.at(0));
 
    if( etaMin_hists.find(inputParameters.at(1)) == etaMin_hists.end()) {
        //this should never be reached
        return 0.;
    }
 
    //get the chosen histogram from the map
    TH1*  hist = etaMin_hists.at(inputParameters.at(1));
 
    //Draw randomly from the histogram CDF distribution.
    double randomShoot = CLHEP::RandFlat::shoot(rndmEngine);
 
    //first select the matching CDF bin
    int iBinSelect = 0;
    for(int iBin = 0; iBin < hist->GetNbinsX(); iBin ++){
        iBinSelect = iBin;
        if(hist->GetBinContent(iBin) > randomShoot){
            break;
        }
    }
 
    //Select random value within bin
    randomHist = CLHEP::RandFlat::shoot(rndmEngine, hist->GetBinLowEdge(iBinSelect) , hist->GetBinLowEdge(iBinSelect+1));
 
    return randomHist;
 
}