Reweight.cc

#ifndef Reweight_h
#define Reweight_h

#include <stdio.h>
#include <iostream>

#include "TFile.h"
#include "TH1D.h"
#include "TH1F.h"

class ReweightPU {

  public:

      ReweightPU(TString filenameData) {

      fileData_ = 0;
      fileData_ = new TFile(filenameData, "READ");

      if (!fileData_) {
        cout << "\n\n Data file of the Nvtx reweighting could not be opened!" << endl;
      }

      h_Data_ = 0;
      h_Data_ = (TH1D*)fileData_->Get("pileup");
      if (!h_Data_) cout << "Can't open PU data reweight histo";

// Distribution used for Summer2012 MC.

      Double_t Summer2012_S10[60] = {
                         2.560E-06,
                         5.239E-06,
                         1.420E-05,
                         5.005E-05,
                         1.001E-04,
                         2.705E-04,
                         1.999E-03,
                         6.097E-03,
                         1.046E-02,
                         1.383E-02,
                         1.685E-02,
                         2.055E-02,
                         2.572E-02,
                         3.262E-02,
                         4.121E-02,
                         4.977E-02,
                         5.539E-02,
                         5.725E-02,
                         5.607E-02,
                         5.312E-02,
                         5.008E-02,
                         4.763E-02,
                         4.558E-02,
                         4.363E-02,
                         4.159E-02,
                         3.933E-02,
                         3.681E-02,
                         3.406E-02,
                         3.116E-02,
                         2.818E-02,
                         2.519E-02,
                         2.226E-02,
                         1.946E-02,
                         1.682E-02,
                         1.437E-02,
                         1.215E-02,
                         1.016E-02,
                         8.400E-03,
                         6.873E-03,
                         5.564E-03,
                         4.457E-03,
                         3.533E-03,
                         2.772E-03,
                         2.154E-03,
                         1.656E-03,
                         1.261E-03,
                         9.513E-04,
                         7.107E-04,
                         5.259E-04,
                         3.856E-04,
                         2.801E-04,
                         2.017E-04,
                         1.439E-04,
                         1.017E-04,
                         7.126E-05,
                         4.948E-05,
                         3.405E-05,
                         2.322E-05,
                         1.570E-05,
                         5.005E-06};

      h_MCmod_ = (TH1D*)h_Data_->Clone("h_MCmod_");
      for (Int_t i = 1; i < 61; i++) {
        h_MCmod_->SetBinContent(i, Summer2012_S10[i-1]);
      }

      double int_MC_ = h_MCmod_->Integral();
      double int_Data_ = h_Data_->Integral();

      h_Data_->Divide(h_MCmod_);
      h_Data_->Scale(int_MC_ / int_Data_);

/*
      cout << endl;
      for (Int_t i = 1; i < 61; i++)
        cout << h_Data_->GetBinContent(i) <<endl;
*/
    }

    ~ReweightPU() {
      delete fileData_;
      delete h_MCmod_;
      delete h_Data_;
    }

    double GetWeight(double nvtx) {
      
      return h_Data_->GetBinContent( h_Data_->FindBin(nvtx) );

    }

  private:

    TFile* fileData_;

    TH1D* h_MCmod_;
    TH1D* h_Data_;
};

#endif