// Ottimizza Significanza Statistica con un taglio sulla variabile var2
#include <TLegend.h>
#include <TH1.h>
#include <TH1F.h>
#include <TMath>
void Ottim_Signif_1D()
{
  gROOT->Reset();
  
  
  gStyle->SetHistLineColor(4);

  TFile *f = new TFile("mva1_sample.root");

  TTree* signalTree = (TTree*)f->Get("signal");
  TTree* bkgTree = (TTree*)f->Get("bkg");

  Double_t var1, var2, eff_s,rej_b, FOM, vcut, vcut0 = 0.05;  
  Int_t i, ns, nbkg, ntot;
  
  Double_t varMin=0.0, varMax = 1.1;
  
  signalTree->SetBranchAddress("var1",&var1);
  signalTree->SetBranchAddress("var2",&var2);
  
  bkgTree->SetBranchAddress("var1",&var1);
  bkgTree->SetBranchAddress("var2",&var2);

  Int_t n_sigEntries = (Int_t)signalTree->GetEntries();
  cout << "Num. of signal entries: " << n_sigEntries << endl;
  
  Int_t n_bkgEntries = (Int_t)bkgTree->GetEntries();
  cout << "Num. of background entries: " << n_bkgEntries << endl;
 
  TCanvas* c1= new TCanvas("c1","Istogrammi",1);
  
  c1->Divide(2);  
  TPad* c1_1 =   c1->cd(1);
  c1_1->SetLogy();



  TH1F* h1 = new TH1F ("h1", "var1", 50,0.0, 1.4);
  TH1F* h1s = new TH1F ("h1s", "var2", 50,0.0, 1.4);

  h1->SetLineColor(1);
  h1->SetLineStyle(1);
  h1->SetStats(kFALSE);
  h1->GetXaxis()->SetTitle("var1");
  h1->GetYaxis()->SetTitle("Events/bin");
  
  signalTree-> Draw("var1>>h1");  
  
  h1s->SetLineColor(2);
  h1s->TH1F::SetLineStyle(2);
  bkgTree-> Draw("var1>>h1s", "","SAME");
  
  TLegend *leg  = new TLegend(0.75, 0.75, 0.89, 0.89);
  leg -> AddEntry(h1,"Signal");
  leg->AddEntry(h1s, "Bkg");
  leg->SetFillColor(0);
  leg->SetTextSize(0.04);
  leg->Draw();

  
  c1->cd(2);  
  TH1F* h2 = new TH1F ("h2", "va2", 50,0.0, 1.1);
  TH1F* h2s = new TH1F ("h2s", "var2", 50,0.0, 1.1);
  
  h2->SetLineColor(2);
  h2->SetLineStyle(2);
  h2->SetStats(kFALSE);  
  h2->GetXaxis()->SetTitle("var2");
  h2->GetYaxis()->SetTitle("Events/bin");
  bkgTree-> Draw("var2>>h2");  
       
  h2s->SetLineColor(1);
  h2s->TH1F::SetLineStyle(1);
  signalTree-> Draw("var2>>h2s","","SAME");  


  TLegend *leg2  = new TLegend(0.75, 0.75, 0.89, 0.89);
  leg2 -> AddEntry(h2s,"Signal");
  leg2->AddEntry(h2, "Bkg");
  leg2->SetFillColor(0);
  leg2->SetTextSize(0.04);
  leg2->Draw();

//Optimizing  signal statistical significance 

   TCanvas* c2 = new TCanvas("c2","eff_s",200,30,700,500);
   TCanvas* c3 = new TCanvas("c3","rej_b",200,30,700,500);
   TCanvas* c4 = new TCanvas("c4","FOM",220,50,700,500);
   TCanvas* c5 = new TCanvas("c5","ROC",240,70,700,500);
  

  


  TGraph *effs = new TGraph();
  TGraph *effss = new TGraph();
  TGraph *bkgRej = new TGraph();
  TGraph *FOMg = new TGraph();
  TGraph *ROC = new TGraph();

  
  const Int_t ncuts = int((varMax-varMin)/vcut0);

		for (i=0; i<ncuts; i++)
		{
		stringstream buffer;
		buffer << "var2<" << vcut;
		ns = signalTree-> Draw("var2", (buffer.str()) .c_str());
		nbkg = bkgTree-> Draw("var2", (buffer.str()) .c_str());

		eff_s = Double_t(ns)/Double_t(n_sigEntries);
		effs->SetPoint(i, vcut, eff_s);
		effss->SetPoint(i, vcut, eff_s);
		
		rej_b = (Double_t(n_bkgEntries) -Double_t(nbkg))/Double_t(n_bkgEntries); 
		bkgRej -> SetPoint(i, vcut, rej_b);
		
		ntot = ns + nbkg;
		if(ntot<1) ntot=1;
		if(nbkg <1) nbkg=1;
		
		FOM = Double_t (ns)/sqrt(ntot);
//		FOM = Double_t(ns)/sqrt(nbkg);
		FOMg-> SetPoint(i, vcut, FOM);  
		ROC -> SetPoint(i, eff_s, rej_b);
		
		vcut = (i+1)*vcut0;
		}

  
 
  c2 ->cd();
  effs ->SetTitle("Signal ");
  effs->GetXaxis()->SetTitle("var2");
  effs->GetYaxis()->SetTitle("Signal Efficiency");
  effs ->SetFillColor(35);
  effs ->SetMarkerStyle(21);
  effs->SetMarkerColor(4);
  effs->Draw("APL");


 
  c3 ->cd();
  bkgRej->GetXaxis()->SetTitle("var2");
  bkgRej->GetYaxis()->SetTitle("Bkg Rejection Efficiency");
  bkgRej ->SetFillColor(35);
  bkgRej ->SetTitle("Background Rejection");
  bkgRej ->SetMarkerStyle(21);
  bkgRej->SetMarkerColor(2);
  bkgRej->Draw("APL");
  
  
  c4 ->cd();
  FOMg->GetXaxis()->SetTitle("var2");
  FOMg->GetYaxis()->SetTitle("FOM");

  FOMg ->SetFillColor(35);
  FOMg->SetMarkerColor(3);
  FOMg ->SetTitle("FOM");
  FOMg ->SetMarkerStyle(21);
  FOMg->Draw("APC");
  
  c5 ->cd();
  ROC->GetXaxis()->SetTitle("var2");
  ROC->GetYaxis()->SetTitle("ROC");
  ROC ->SetFillColor(35);
  ROC ->SetTitle("ROC");
  ROC ->SetMarkerStyle(21);
  ROC->SetMarkerColor(3);
  ROC->Draw("APC");
   
  

  TCanvas* all = new TCanvas ("all","All in one");
  all->Divide(2,2);
  all_1->cd();
  effss->GetYaxis()->SetTitle("Efficiency");
  effss ->SetTitle("Signal Efficiency and Background Rejection");
  effss ->SetMarkerStyle(21);
  effss->SetMarkerColor(1);
  effss->Draw("APL");   
   
  bkgRej ->SetFillColor(35);

  bkgRej ->SetMarkerStyle(21);
  bkgRej->SetLineColor(2);
  bkgRej->SetMarkerColor(2);

  bkgRej -> Draw("PL");
  leg = new TLegend(0.60, 0.80, 0.88, 0.88);
  leg->SetHeader("Black=S; Red=B");
  leg->SetTextSize(0.05);	
  leg->Draw();
	   
    
  all_2->cd();
  FOMg->SetMarkerColor(3);
  FOMg->Draw("APL");
  all_3->cd();
  ROC->GetYaxis()->SetTitle("Background Rejection");
  ROC->GetXaxis()->SetTitle("Signal Efficiency");
  ROC->SetMarkerColor(4);
  
  ROC->Draw("APL");
}