void test_TH2D() {
  gStyle->SetOptStat(111111);

  TCanvas* canvas = new TCanvas("canvas","",800,500);
  canvas->Divide(2,2);

  TH2D* h21 = new TH2D("h21","",3,0,3,3,0,3);
  Double_t x,y ;
  
  x=1;
  y=1;
  h21->Fill(x,y);
  x=2;
  h21->Fill(x,y);
  x=7;
  h21->Fill(x,y);
  

  TH2D* h22 = (TH2D*) h21->Clone("h22");

  h21->GetXaxis()->SetRange(1,3);
  h22->GetXaxis()->SetRange(1,2);
  
  TH1D* h11 = h21->ProjectionY();
  TH1D* h12 = h22->ProjectionY();

  canvas->cd(1);
  h21->Draw("colz");
  canvas->cd(2);
  h22->Draw("colz");
  canvas->cd(3);
  h11->Draw();
  canvas->cd(4);
  h12->Draw();
  

}