Single_trkeff_pt.cxx

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void Single_trkeff_pt( char* file = "Single" ) {
  Double_t x[10]    = { .1, .2, .3, .4, .5, .6, .7, .8, .9, 1. };
  Double_t errx[10] = { 0 };
  Double_t effpt[10];
  Double_t errpt[10];
  Double_t eventNo = 5000.;
  Char_t   filename[100];
  Char_t   name[100];
 
  for ( Int_t i = 0; i < 10; i++ )
  {
    sprintf( name, "%d.root", i );
    strcpy( filename, file );
    strcat( filename, name );
 
    TFile f( filename );
    runinfo->Draw( "runinfo_ngood", "runinfo_ngood>0.5" );
    effpt[i] = htemp->GetEntries() / eventNo;
  }
 
  for ( Int_t i = 0; i < 10; i++ )
  { errpt[i] = sqrt( effpt[i] * ( 1. - effpt[i] ) / eventNo ); }
 
  TGraph* gr1 = new TGraphErrors( 10, x, effpt, errx, errpt );
 
  TCanvas*     c1 = new TCanvas( "c1", "pioneff", 100, 10, 600, 400 );
  TMultiGraph* mg = new TMultiGraph();
 
  c1->SetGrid();
  mg->SetTitle( "pioneff" );
  gr1->SetLineColor( 2 );
 
  mg->Add( gr1 );
  mg->Draw( "ALP" );
  mg->GetYaxis()->SetRangeUser( 0, 1 );
  mg->GetXaxis()->SetTitle( "Pt/GeV" );
  mg->GetYaxis()->SetTitle( "Eff" );
 
  TLegend* legend = new TLegend( 0.7, 0.65, 0.85, 0.75 );
  legend->AddEntry( gr1, "pion_Pt", "l" );
  legend->Draw();
}