ThinNegativeEnergyNeutralPFOsAlg.cxx

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/*
  Copyright (C) 2002-2022 CERN for the benefit of the ATLAS collaboration
*/
 
// ThinNegativeEnergyNeutralPFOsAlg.cxx
// Author: Chris Young <christopher.young@cern.ch>
// based on similar code by Karsten Koeneke <karsten.koeneke@cern.ch>
// and James Catmore <James.Catmore@cern.ch>
// Uses thinning service to remove Neutral PFOs with negative energy
// Intended for use in ESD->AOD in reconstruction - use other tools
// for analysis (Expression evaluation is not used here)
 
// EventUtils includes
#include "ThinNegativeEnergyNeutralPFOsAlg.h"
#include "xAODPFlow/PFOContainer.h"
 
// STL includes
#include <algorithm>
 
// FrameWork includes
#include "Gaudi/Property.h"
#include "GaudiKernel/ThreadLocalContext.h"
#include "StoreGate/ThinningHandle.h"

// Public methods:
 
// Constructors
ThinNegativeEnergyNeutralPFOsAlg::ThinNegativeEnergyNeutralPFOsAlg(
  const std::string& name,
  ISvcLocator* pSvcLocator)
  : AthReentrantAlgorithm(name, pSvcLocator)
  , m_nEventsProcessed(0)
  , m_nNeutralPFOsProcessed(0)
  , m_nNeutralPFOsThinned(0)
{
}
 
// Athena Algorithm's Hooks
StatusCode
ThinNegativeEnergyNeutralPFOsAlg::initialize()
{
  ATH_MSG_DEBUG("Initializing " << name() << "...");
 
  // Print out the used configuration
  ATH_MSG_DEBUG(" using = " << m_streamName);
 
  // Is truth thinning required?
  if (!m_doThinning) {
    ATH_MSG_INFO("Negative energy NeutralPFO thinning not required");
  } else {
    ATH_MSG_INFO("Negative energy NeutralPFOs will be thinned");
  }
 
  if (m_doThinning && m_streamName.empty()) {
    ATH_MSG_ERROR("StreamName property has not been initialized.");
    return StatusCode::FAILURE;
  }
  ATH_CHECK(m_neutralPFOsKey.initialize(
    m_streamName, m_doThinning && !m_neutralPFOsKey.key().empty()));
  ATH_CHECK(m_LCNeutralPFOsKey.initialize(
    m_streamName, m_doThinning && !m_LCNeutralPFOsKey.key().empty()));
 
  // Initialize the counters to zero
  m_nEventsProcessed = 0;
  m_nNeutralPFOsProcessed = 0;
  m_nNeutralPFOsThinned = 0;
 
  ATH_MSG_DEBUG("==> done with initialize " << name() << "...");
 
  return StatusCode::SUCCESS;
}
 
StatusCode
ThinNegativeEnergyNeutralPFOsAlg::finalize()
{
  ATH_MSG_DEBUG("Finalizing " << name() << "...");
  ATH_MSG_INFO("Processed " << m_nEventsProcessed << " events containing "
                            << m_nNeutralPFOsProcessed << " NeutralPFOs");
  ATH_MSG_INFO("Removed " << m_nNeutralPFOsThinned
                          << " negative energy NeutralPFOs ");
  return StatusCode::SUCCESS;
}
 
StatusCode
ThinNegativeEnergyNeutralPFOsAlg::execute(const EventContext& ctx) const
{
  // Increase the event counter
  m_nEventsProcessed.fetch_add(1, std::memory_order_relaxed);
 
  // Is truth thinning required?
  if (!m_doThinning || m_neutralPFOsKey.key().empty()) {
    return StatusCode::SUCCESS;
  }
 
  SG::ThinningHandle<xAOD::FlowElementContainer> neutralFEs(m_neutralPFOsKey,
                                                            ctx);
  std::vector<bool> mask;
  int nNeutralFEs = neutralFEs->size();
  m_nNeutralPFOsProcessed.fetch_add(nNeutralFEs, std::memory_order_relaxed);
  mask.assign(nNeutralFEs, false);
 
  unsigned long int nNeutralPFOsThinned = 0;
  for (int i = 0; i < nNeutralFEs; i++) {
    const xAOD::FlowElement* neutralFE = (*neutralFEs)[i];
    if (neutralFE->pt() > 0.0)
      mask[i] = true;
    else {
      ++nNeutralPFOsThinned;
    }
  }
 
  m_nNeutralPFOsThinned.fetch_add(nNeutralPFOsThinned,
                                  std::memory_order_relaxed);
  neutralFEs.keep(mask);
 
  if (!m_LCNeutralPFOsKey.key().empty()) {
    SG::ThinningHandle<xAOD::FlowElementContainer> LCNeutralFEs(
      m_LCNeutralPFOsKey, ctx);
    // LC PFOs are thinned based on the energy of the (EM-scale) originals
    LCNeutralFEs.keep(mask);
  }
  return StatusCode::SUCCESS;
}