readTree.cxx

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void readTree() {
  int       rBin, phiBin, zBin;
  const int nR   = 43;
  const int nPhi = 6;
  const int nZ   = 6;
  float     eff, x[400], y[400];
 
  TFile* f = new TFile( "effTree.root", "read" );
  TTree* t = (TTree*)f->Get( "effTree" );
 
  t->SetBranchAddress( "rBin", &rBin );
  t->SetBranchAddress( "phiBin", &phiBin );
  t->SetBranchAddress( "zBin", &zBin );
  t->SetBranchAddress( "eff", &eff );
  t->SetBranchAddress( "x", x );
  t->SetBranchAddress( "y", y );
 
  int   r, phi, z;
  float efficiency[43][6][6];
  float propTime[43][6][6][400];
  float prob[43][6][6][400];
 
  for ( Int_t i = 0; i < nR * nPhi * nZ; i++ )
  {
    t->GetEntry( i );
    r                     = rBin;
    phi                   = phiBin;
    z                     = zBin;
    efficiency[r][phi][z] = eff;
    for ( Int_t j = 0; j < 400; j++ )
    {
      propTime[r][phi][z][j] = x[j];
      prob[r][phi][z][j]     = y[j];
      // cout << "\n" << propTime[r][phi][z][j] << "   " << prob[r][phi][z][j] << endl;
    }
  }
  // TH1F *h1 = new TH1F("h1","propTime",400,0,20);
  int     r0   = 41;
  int     phi0 = 2;
  int     z0   = 0;
  Float_t x0[400], y0[400];
 
  char  file[200];
  int   rPos = 400 + r0 * 10;
  float x1[400], y1[400];
  float t1;
  sprintf( file, "/ihepbatch/besd12/liuy/EndcapTof/OpInETof2/results/%d/timeSta_%d_%d_%d.root",
           rPos, rPos, phi0, z0 );
  cout << file << endl;
  TH1F*    h1 = new TH1F( "h1", "time distr.(ns)", 400, 0, 20 );
  TFile*   f1 = TFile::Open( file );
  TNtuple* n1 = (TNtuple*)f1->Get( "timeTuple" );
  n1->SetBranchAddress( "inTimePre", &t1 );
  int nEntries = (Int_t)n1->GetEntries();
  cout << "nEntries:" << nEntries << "\n" << endl;
 
  for ( int m = 0; m < nEntries; m++ )
  {
    n1->GetEntry( m );
    h1->Fill( t1 );
  }
  double norm = h1->Integral();
  eff         = norm / 2000000.; // 200 events per run ; 10k photons per event
  if ( norm != 0 ) h1->Scale( 1. / norm );
  else
  {
    cout << "The eff is null!" << endl;
    continue;
  }
  TAxis* xaxis = h1->GetXaxis();
  for ( int m = 0; m < 400; m++ )
  {
    x1[m] = xaxis->GetBinCenter( m );
    y1[m] = h1->GetBinContent( m );
  }
  f1->Close();
 
  for ( Int_t i = 0; i < 400; i++ )
  {
    x0[i] = propTime[r0][phi0][z0][i] - x1[i];
    y0[i] = prob[r0][phi0][z0][i] - y1[i];
  }
 
  TGraph* g = new TGraph( 400, x0, y0 );
  g->Draw( "APL" );
 
  f->Close();
}