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();
}