LumiReWeighting.cc

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#ifndef PhysicsTools_Utilities_interface_LumiReWeighting_cc
#define PhysicsTools_Utilities_interface_LumiReWeighting_cc


#include "TRandom1.h"
#include "TRandom2.h"
#include "TRandom3.h"
#include "TStopwatch.h"
#include "TH1.h"
#include "TFile.h"
#include <iostream>
#include <string>
#include <algorithm>
#include <boost/shared_ptr.hpp>
#include "SimDataFormats/PileupSummaryInfo/interface/PileupSummaryInfo.h" 
#include "PhysicsTools/Utilities/interface/LumiReWeighting.h"
#include "DataFormats/Common/interface/Handle.h"
#include "DataFormats/Provenance/interface/ProcessHistory.h"
#include "DataFormats/Provenance/interface/Provenance.h"
#include "FWCore/Common/interface/EventBase.h"

using namespace edm;

LumiReWeighting::LumiReWeighting( std::string generatedFile,
           std::string dataFile,
           std::string GenHistName,
           std::string DataHistName,
           const edm::InputTag& PileupSumInfoInputTag ) :
      generatedFileName_( generatedFile), 
      dataFileName_     ( dataFile ), 
      GenHistName_      ( GenHistName ), 
      DataHistName_     ( DataHistName ),
      pileupSumInfoTag_ ( PileupSumInfoInputTag )
      {
    generatedFile_ = boost::shared_ptr<TFile>( new TFile(generatedFileName_.c_str()) ); //MC distribution
    dataFile_      = boost::shared_ptr<TFile>( new TFile(dataFileName_.c_str()) );      //Data distribution

    Data_distr_ = boost::shared_ptr<TH1>(  (static_cast<TH1*>(dataFile_->Get( DataHistName_.c_str() )->Clone() )) );
    MC_distr_ = boost::shared_ptr<TH1>(  (static_cast<TH1*>(generatedFile_->Get( GenHistName_.c_str() )->Clone() )) );

    // MC * data/MC = data, so the weights are data/MC:

    // normalize both histograms first

    Data_distr_->Scale( 1.0/ Data_distr_->Integral() );
    MC_distr_->Scale( 1.0/ MC_distr_->Integral() );

    weights_ = boost::shared_ptr<TH1>( static_cast<TH1*>(Data_distr_->Clone()) );

    weights_->SetName("lumiWeights");

    TH1* den = dynamic_cast<TH1*>(MC_distr_->Clone());

    //den->Scale(1.0/ den->Integral());

    weights_->Divide( den );  // so now the average weight should be 1.0

    std::cout << " Lumi/Pileup Reweighting: Computed Weights per In-Time Nint " << std::endl;

    int NBins = weights_->GetNbinsX();

    for(int ibin = 1; ibin<NBins+1; ++ibin){
      std::cout << "   " << ibin-1 << " " << weights_->GetBinContent(ibin) << std::endl;
    }


    FirstWarning_ = true;
    OldLumiSection_ = -1;
}

LumiReWeighting::LumiReWeighting(const std::vector< float >& MC_distr,const std::vector< float >& Lumi_distr, const edm::InputTag& PileupSumInfoInputTag ) :
      pileupSumInfoTag_ ( PileupSumInfoInputTag )
  {
  // no histograms for input: use vectors
  
  // now, make histograms out of them:

  // first, check they are the same size...

  if( MC_distr.size() != Lumi_distr.size() ){   

    std::cerr <<"ERROR: LumiReWeighting: input vectors have different sizes. Quitting... \n";
    return;

  }

  Int_t NBins = MC_distr.size();

  MC_distr_ = boost::shared_ptr<TH1> ( new TH1F("MC_distr","MC dist",NBins,-0.5, float(NBins)-0.5) );
  Data_distr_ = boost::shared_ptr<TH1> ( new TH1F("Data_distr","Data dist",NBins,-0.5, float(NBins)-0.5) );

  weights_ = boost::shared_ptr<TH1> ( new TH1F("luminumer","luminumer",NBins,-0.5, float(NBins)-0.5) );
  TH1* den = new TH1F("lumidenom","lumidenom",NBins,-0.5, float(NBins)-0.5) ;

  for(int ibin = 1; ibin<NBins+1; ++ibin ) {
    weights_->SetBinContent(ibin, Lumi_distr[ibin-1]);
    Data_distr_->SetBinContent(ibin, Lumi_distr[ibin-1]);
    den->SetBinContent(ibin,MC_distr[ibin-1]);
    MC_distr_->SetBinContent(ibin,MC_distr[ibin-1]);
  }

  // check integrals, make sure things are normalized

  float deltaH = weights_->Integral();
  if(fabs(1.0 - deltaH) > 0.02 ) { //*OOPS*...
    weights_->Scale( 1.0/ weights_->Integral() );
    Data_distr_->Scale( 1.0/ Data_distr_->Integral() );
  }
  float deltaMC = den->Integral();
  if(fabs(1.0 - deltaMC) > 0.02 ) {
    den->Scale(1.0/ den->Integral());
    MC_distr_->Scale(1.0/ MC_distr_->Integral());
  }

  weights_->Divide( den );  // so now the average weight should be 1.0    

  std::cout << " Lumi/Pileup Reweighting: Computed Weights per In-Time Nint " << std::endl;

  for(int ibin = 1; ibin<NBins+1; ++ibin){
    std::cout << "   " << ibin-1 << " " << weights_->GetBinContent(ibin) << std::endl;
  }

  FirstWarning_ = true;
  OldLumiSection_ = -1;
}

double LumiReWeighting::weight( int npv ) {
  int bin = weights_->GetXaxis()->FindBin( npv );
  return weights_->GetBinContent( bin );
}

double LumiReWeighting::weight( float npv ) {
  int bin = weights_->GetXaxis()->FindBin( npv );
  return weights_->GetBinContent( bin );
}



// This version of weight does all of the work for you, assuming you want to re-weight
// using the true number of interactions in the in-time beam crossing.


double LumiReWeighting::weight( const edm::EventBase &e ) {

  if(FirstWarning_) {
    e.processHistory();
    //    SetFirstFalse();
    FirstWarning_ = false;
  }
  Handle<std::vector< PileupSummaryInfo > >  PupInfo;
  e.getByLabel(pileupSumInfoTag_, PupInfo);

  std::vector<PileupSummaryInfo>::const_iterator PVI;

  int npv = -1;
  for(PVI = PupInfo->begin(); PVI != PupInfo->end(); ++PVI) {

    int BX = PVI->getBunchCrossing();

    if(BX == 0) { 
      npv = PVI->getPU_NumInteractions();
      continue;
    }

  }

  if(npv < 0) std::cerr << " no in-time beam crossing found\n! " ;

  return weight(npv);

}

// Use this routine to re-weight out-of-time pileup to match the in-time distribution
// As of May 2011, CMS is only sensitive to a bunch that is 50ns "late", which corresponds to
// BunchCrossing +1.  So, we use that here for re-weighting.

double LumiReWeighting::weightOOT( const edm::EventBase &e ) {


  //int Run = e.run();
  int LumiSection = e.luminosityBlock();
  // do some caching here, attempt to catch file boundaries

  if(LumiSection != OldLumiSection_){
    e.processHistory(); // keep the function call
    OldLumiSection_ = LumiSection;
  }
  // find the pileup summary information

  Handle<std::vector< PileupSummaryInfo > >  PupInfo;
  e.getByLabel(pileupSumInfoTag_, PupInfo);

  std::vector<PileupSummaryInfo>::const_iterator PVI;

  int npv = -1;
  int npv50ns = -1;

  for(PVI = PupInfo->begin(); PVI != PupInfo->end(); ++PVI) {

    int BX = PVI->getBunchCrossing();

    if(BX == 0) { 
      npv = PVI->getPU_NumInteractions();
    }

    if(BX == 1) { 
      npv50ns = PVI->getPU_NumInteractions();
    }

  }

  // Note: for the "uncorrelated" out-of-time pileup, reweighting is only done on the 50ns
  // "late" bunch (BX=+1), since that is basically the only one that matters in terms of 
  // energy deposition.  

  if(npv < 0) {
    std::cerr << " no in-time beam crossing found\n! " ;
    std::cerr << " Returning event weight=0\n! ";
    return 0.;
  }
  if(npv50ns < 0) {
    std::cerr << " no out-of-time beam crossing found\n! " ;
    std::cerr << " Returning event weight=0\n! ";
    return 0.;
  }

  int bin = weights_->GetXaxis()->FindBin( npv );

  double inTimeWeight = weights_->GetBinContent( bin );

  double TotalWeight = 1.0;

  TotalWeight = inTimeWeight;

  return TotalWeight;
 
}

#endif