gROOT->Reset();

#include "TChain.h"
#include "TTree.h"
#include "TObject.h"
#include "TArray.h"
#include "TFile.h"
#include "TList.h"
#include "TCanvas.h"
#include "TAxis.h"
#include "TH1.h"
#include "TMath.h"

void norm(TH1F* hist)
{
  
  // normalizes a 1-d histogram to its bin width and number of events
 
  hist->Sumw2(); 
  hist->Scale(1.0 / hist->Integral(),"width"); //new... Rene"s suggestion// 

 /* for (Int_t i=1; i<=hist->GetNbinsX(); ++i)
  {
    hist->SetBinContent(i, hist->GetBinContent(i) / hist->GetBinWidth(i));
    hist->SetBinError(i, hist->GetBinError(i) / hist->GetBinWidth(i));
  }*/
 
}

void style(TH1F* hist){
 //removes stat box and title. just for reduce the line numbers//
  hist->SetStats(kFALSE);
  hist->SetBit(TH1::kNoTitle);
}
void Draw_eff_draw(){

TFile *strangefile = TFile::Open("StrangeSpectra_perugia_900GeV_596700_event.root", "read");
TList *liststrange = strangefile-> Get("coutput");

//get Y histograms from root file. B: abs(y)>0.9 C:abs(y)>0.5 D:abs(y)>2.5
B_LAMBDA = (TH1F*)(liststrange->FindObject("fMCYLambdapt0y09")) ; 
C_LAMBDA = (TH1F*)(liststrange->FindObject("fMCYLambdapt0y05")) ; 
D_LAMBDA = (TH1F*)(liststrange->FindObject("fMCYLambdapt0y25")) ; 

//make sumw2 for division
B_LAMBDA->Sumw2();
C_LAMBDA->Sumw2();
D_LAMBDA->Sumw2();

//create a ratio histograms
//binning and x-axis range same as original the distributions at root file
TH1F *B_RATIO =new TH1F("B_RATIO", " Y distribution Lambda/Lambda Ratio for p_{T} >0 and Y>0.9",15,-3,3 ) ; 
B_RATIO->SetMarkerStyle(20);
TH1F *C_RATIO =new TH1F("C_RATIO", " Y distribution Lambda/Lambda Ratio for p_{T} >0 and Y>0.5",15,-3,3 ) ; 
C_RATIO->SetMarkerStyle(22);
TH1F *D_RATIO =new TH1F("D_RATIO", " Y distribution Lambda/Lambda Ratio for p_{T} >0 and Y>2.5",15,-3,3 ) ; 
D_RATIO->SetMarkerStyle(24);

B_RATIO->Divide(B_LAMBDA,B_LAMBDA);  //should give 1//
C_RATIO->Divide(C_LAMBDA,C_LAMBDA);  //should give 1//
D_RATIO->Divide(D_LAMBDA,D_LAMBDA);  //should give 1//

//copy ratio histograms for normalization 
TH1F *B_RATIOnorm = new TH1F(*B_RATIO);   
TH1F *C_RATIOnorm = new TH1F(*C_RATIO);   
TH1F *D_RATIOnorm = new TH1F(*D_RATIO);   

//normalize histograms
norm(B_RATIOnorm);   norm(C_RATIOnorm);  norm(D_RATIOnorm);

//remove stat boxes and titles
style(B_RATIO);      style(C_RATIO);     style(D_RATIO);
style(B_RATIOnorm);  style(C_RATIOnorm); style(D_RATIOnorm);

//draw ratio histograms
TCanvas *c1 = new TCanvas("c1","+1+ ORIGINAL");
B_RATIO->GetYaxis()->SetRangeUser(0,1.5);
B_RATIO->Draw("e1p");
C_RATIO->Draw("e1psame");
D_RATIO->Draw("e1psame");
c1->BuildLegend(0.29,0.78,0.99,0.97);
c1->SaveAs("before_normalization.png");

//draw normalized ratio histograms
TCanvas *c2_normalized = new TCanvas("c2_normalized","+2+ NORMALIZED");
B_RATIOnorm->GetYaxis()->SetRangeUser(0,1.4);
B_RATIOnorm->Draw("e1p");
C_RATIOnorm->Draw("e1psame");
D_RATIOnorm->Draw("e1psame");
c2_normalized->BuildLegend(0.29,0.78,0.99,0.97);
c2_normalized->SaveAs("after_normalization.png");
}