{
   //canvas only needed for this documentation
   TCanvas* c1 = new TCanvas("example","",600,400);
   c1->SetFillStyle(1001);
   c1->SetFillColor(kWhite);
   //create one-dimensional TEfficiency object with fixed bin size
   TEfficiency* pEff = new TEfficiency("eff","my efficiency;x;#epsilon",20,0,10);
   TRandom3 rand3;
   bool bPassed;
   double x;
   for(int i=0; i<10000; ++i)
   {
      //simulate events with variable under investigation
      x = rand3.Uniform(10);
      //check selection: bPassed = DoesEventPassSelection(x)
      bPassed = rand3.Rndm() < TMath::Gaus(x,5,4);
      pEff->Fill(bPassed,x);
   }
   pEff->Draw("AP");
//    pEff->Paint("AP");
   c1->Pad()->Update();

   TGraphAsymmErrors *gg=pEff->GetPaintedGraph();
   
   cout << gg << endl;
   
   if(gg){
    TAxis *ax = gg->GetXaxis();
    Double_t x1 = ax->GetBinLowEdge(1);
    Double_t x2 = ax->GetBinUpEdge(ax->GetNbins());
    cout << x1 << ";" << x2 <<endl;
    ax->Set(20,0,10);
    TAxis *ay = gg->GetYaxis();
    ay->SetRangeUser(0,1.0); // overwrite auto

    vector <string > names={
        "aaa","bbb","ccc","ddd","eee","fff","ggg","hhh","iii","jjj",
        "aaa","bbb","ccc","ddd","eee","fff","ggg","hhh","iii","jjj"
        };
    for(Int_t k=0;k<20;k++){
        ax->SetBinLabel(k+1,names[k].c_str());
    }
    c1->Print("c1.root");
    c1->Print("c1.C");
//     pEff->Draw("AP");
   }
   c1->Print("c2.root");
   c1->Print("c2.C");
   c1->Pad()->Update();
//    c1->Draw();
   c1->Print("c3.root");
   c1->Print("c3.C");
//    c1->Paint();
   c1->Print("c4.root");
   c1->Print("c4.C");
   c1->Update();
   c1->Print("c5.root");
   c1->Print("c5.C");
   return c1;
}