TopologyFastSimulation.cxx

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// Copyright 2019-2020 CERN and copyright holders of ALICE O2.
// See https://alice-o2.web.cern.ch/copyright for details of the copyright holders.
// All rights not expressly granted are reserved.
//
// This software is distributed under the terms of the GNU General Public
// License v3 (GPL Version 3), copied verbatim in the file "COPYING".
//
// In applying this license CERN does not waive the privileges and immunities
// granted to it by virtue of its status as an Intergovernmental Organization
// or submit itself to any jurisdiction.
 
 
#include "ITSMFTReconstruction/TopologyFastSimulation.h"
#include <algorithm>
 
ClassImp(o2::itsmft::TopologyFastSimulation);
 
namespace o2
{
namespace itsmft
{
TopologyFastSimulation::TopologyFastSimulation(std::string fileName, unsigned seed)
{
  mDictionary.readFromFile(fileName);
  double tot_freq = 0.;
  int dictSize = mDictionary.getSize();
  mFreqArray.reserve(dictSize);
  for (int iKey = 0; iKey < dictSize; iKey++) {
    tot_freq += mDictionary.getFrequency(iKey);
    mFreqArray[iKey] = tot_freq;
  }
  mGenerator = std::mt19937(seed);
  mDistribution = std::uniform_real_distribution<double>(0.0, 1.0);
}
 
int TopologyFastSimulation::getRandom()
{
  double rnd = mDistribution(mGenerator);
  auto ind = std::upper_bound(mFreqArray.begin(), mFreqArray.end(), rnd,
                              [](const double& comp1, const double& comp2) { return comp1 < comp2; });
  return std::distance(mFreqArray.begin(), ind);
}
} // namespace itsmft
} // namespace o2