// Example displaying a 2D histogram with its two projections.

{
   TCanvas *c1 = new TCanvas("c1", "c1",900,900);

   gStyle->SetOptStat(0);
   
   // Create the three pads
   TPad *center_pad = new TPad("center_pad", "center_pad",0.0,0.0,0.6,0.6);
   center_pad->Draw();

   right_pad = new TPad("right_pad", "right_pad",0.55,0.0,1.0,0.6);
   right_pad->Draw();

   top_pad = new TPad("top_pad", "top_pad",0.0,0.55,0.6,1.0);
   top_pad->Draw();

   // Create, fill and project a 2D histogram.
   TH2F *h2 = new TH2F("h2","",100, 0, 3.5, 100, 0, 3.5);
   h2->GetXaxis()->SetTitle("M^{2}_{K^{-}#pi^{+}} [GeV^{2}/c^{4}]");
   h2->GetYaxis()->SetTitle("M^{2}_{K^{-}#pi^{0}} [GeV^{2}/c^{4}]");
   h2->GetXaxis()->SetTitleSize(0.04);
   h2->GetYaxis()->SetTitleSize(0.04);
   h2->SetMarkerStyle(7);
   h2->GetXaxis()->CenterTitle();
   h2->GetYaxis()->CenterTitle();
   
   TH1D *h3 = new TH1D("h3","",100, 0, 3.5);

     
   TFile *f = new TFile("total_ntuple_allisSignal.root");
   TTree *tree  = (TTree*)f->Get("tree");
  
   Double_t  deltaM, M2_Kpi, M2_Kpi0;
  tree->SetBranchAddress("deltaM",&deltaM);
  tree->SetBranchAddress("M2_Kpi",&M2_Kpi);
  tree->SetBranchAddress("M2_Kpi0",&M2_Kpi0); 
  

  Int_t nentries = (Int_t)tree->GetEntries();
  for (Int_t i=0; i<nentries; i++)
    {
      tree->GetEntry(i);   
   
   {
     h2->Fill(M2_Kpi, M2_Kpi0);
    
   }
   }
   
  

    
   TH1D * projh2X = h2->ProjectionX();
   TH1D * projh2Y = h2->ProjectionY();

   // Drawing
   center_pad->cd();
   gStyle->SetPalette(1);
   // h2->Draw("TEXT");
   h2->Draw("CONTZ");

   // projection of x and y
   top_pad->cd();
   projh2X->SetFillColor(kBlue+2);
   // projh2X->SetMarkerStyle(20);
   // projh2X->Draw("bar");
   projh2X->Draw("bar");


   right_pad->cd();
   projh2Y->SetFillColor(kBlue+2);
   // projh2Y->SetMarkerStyle(20);
   // projh2Y->Draw("hbar");
   projh2Y->Draw("hbar");

   

   c1->cd();
   TLatex *t = new TLatex();
   t->SetTextFont(42);
   t->SetTextSize(0.02);
   
}