void efficiency()
  
{
  Int_t n = 7;

  Double_t x[7] = {0.5,1.5,2.5,3.5,4.5,5.5,6.5};
  Double_t ex[7] ={0,0,0,0,0,0,0};
  
  Double_t y1[7] = {0.97,0.96,0.92,0.89,0.87,0.87,0.94};
  Double_t ey1[7] = {0.0008,0.0004,0.0005,0.0005,0.0005,0.0005,0.0005};
  
  TGraph *gr1 = new TGraphErrors(n,x,y1,ex,ey1);
   
  gr1->SetMarkerStyle(20);
  gr1->SetMarkerColor(kBlue);
  gr1->SetLineColor(4);
  gr1->SetLineWidth(2);
  //gr1->GetYaxis()->SetRangeUser(0,1);
  //gr1->GetXaxis()->SetRangeUser(0,3);

  TEfficiency* pEff = new TEfficiency("eff","my efficiency;x;Efficiency",7,0,3);
  TFile* f= new TFile("for_tefficiency_0.1.root","read");
  
  TH1F *h1;
  TH1F *h2;

  h1 = (TH1F*)f->Get("Num_p");
  h2 = (TH1F*)f->Get("Den_p");
  
  TFile* pFile = new TFile("myfile.root","recreate");
  if(TEfficiency::CheckConsistency(*h1,*h2))
    {
      pEff = new TEfficiency(*h1,*h2);
      pEff->Write();
      pEff->Draw();
    }

  //Removes the x error bars
  gPad->Update(); 
  TGraph *gr2 = (TGraphAsymmErrors*) pEff->GetPaintedGraph()->Clone();
  for (int i = 0; i < gr2->GetN(); ++i) {
    gr2->GetEXlow()[i] = 0;  
    gr2->GetEXhigh()[i] = 0;  
  }
  gr2->Draw("AP");
  gr2->SetMarkerStyle(20);
  gr2->SetMarkerColor(kRed);
  gr2->SetLineColor(2);
  gr2->SetLineWidth(2);
  //gr2->GetYaxis()->SetRangeUser(0,1);
  //gr2->GetXaxis()->SetRangeUser(0,3);
  // gr2->SetTitle("pionID > 0.1");
  
  TH2D *axes = new TH2D("axes","",7,0.,7.,7,0.,1);
  axes->SetYTitle("Efficiency");
  //axes->SetXTitle("Bins of cos#theta");
  axes->SetXTitle("Bins of momentum");
  axes->GetYaxis()->SetTitleSize(0.04);
  axes->GetYaxis()->SetTitleOffset(1);
  axes->GetYaxis()->CenterTitle();
  axes->GetXaxis()->CenterTitle();
  axes->GetXaxis()->SetLabelSize(0.04);
  axes->GetXaxis()->SetTitleOffset(1.5);
  axes->GetXaxis()->SetBinLabel(1,"0.5 - 1");
  axes->GetXaxis()->SetBinLabel(2,"1 - 1.5");
  axes->GetXaxis()->SetBinLabel(3,"1.5 - 2");
  axes->GetXaxis()->SetBinLabel(4,"2 - 2.5");
  axes->GetXaxis()->SetBinLabel(5,"2.5- 3");
  axes->GetXaxis()->SetBinLabel(6,"3- 3.5");
  axes->GetXaxis()->SetBinLabel(7,"3.5 - 4");
 
  axes->Draw();
  
  TMultiGraph  *mg  = new TMultiGraph();
  mg->Add(gr1);
  mg->Add(gr2);
  mg->Draw("p");

  //c1->BuildLegend();
  TLegend *legend = new TLegend(.75,.80,.95,.95);
  legend->SetFillStyle(0);
  legend->AddEntry(gr1,"sWeighted","pe");
  legend->AddEntry(gr2,"True","pe");

  legend->Draw();
}