puHisto

   /*Data
   JSON=Cert_271036-284044_13TeV_23Sep2016ReReco_Collisions16_JSON.txt
   PUJSON=pileup_latest.txt

  The latest and greatest effective minimum bias cross section, to my knowledge it is 69.2 ± 4.6%  
  MINBIAS=69200
  MINBIASP=72383.2
  MINBIASM=66016.8

  pileupCalc.py -i ${JSON} --inputLumiJSON $PUJSON  --calcMode true --minBiasXsec $MINBIAS --maxPileupBin 50 --numPileupBins 50  outputData.root
  pileupCalc.py -i ${JSON} --inputLumiJSON $PUJSON  --calcMode true --minBiasXsec $MINBIASP --maxPileupBin 50 --numPileupBins 50  outputDataP.root
  pileupCalc.py -i ${JSON} --inputLumiJSON $PUJSON  --calcMode true --minBiasXsec $MINBIASM --maxPileupBin 50 --numPileupBins 50  outputDataM.root

  MC
  python script is:
  from SimGeneral.MixingModule import mix_2016_25ns_Moriond17MC_PoissonOOTPU_cfi as pu

  import ROOT
  n=len(pu.mix.input.nbPileupEvents.probValue )
  x=pu.mix.input.nbPileupEvents.probValue

  f= ROOT.TFile("mcpu.root","recreate")
  pu = ROOT.TH1F("pileup","pileip",n,0,n)

   for i in xrange(0,n) :
   print i
   pu.SetBinContent(i+1,x[i]) 


  pu.Write()
  f.Write()
*/
  
   
   {
   TFile* fileMC = new TFile("mcpu.root");
   TH1D* pileUpMC = (TH1D*)fileMC->Get("pileup");

   TFile* fileData = new TFile("outputData.root");
   TH1D* pileUpData = (TH1D*)fileData->Get("pileup");

   pileUpData->Sumw2();
   pileUpMC->Sumw2();

   pileUpMC->Scale(1./pileUpMC->Integral());
   pileUpData->Scale(1./pileUpData->Integral());


   TH1D* puw = new TH1D("puw","puw”,75,0,75);
   puw->Divide(hpileUpData,hpileUpMC);

   TFile* filePuw = new TFile("puWeights_23Sept.root","recreate");
   puw->Write();
   filePuw->Close();
   
   }