draw_real_dst.cc

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#if ROOT_VERSION_CODE >= ROOT_VERSION(6,00,0)
R__LOAD_LIBRARY(libinterface_main)
#endif

TTree* GetTree(const int run);
void PrintTreeElements(TTree* tree);

void draw_real_dst(const int run=318)
{
  gSystem->Load("libinterface_main.so");

  TTree* tree = GetTree(run);
  //PrintTreeElements(tree); // Call this function if you want.
  tree->SetAlias("event", "DST.SQEvent");
  tree->SetAlias("hit"  , "DST.SQHitVector._vector");

  TCanvas* c1 = new TCanvas("c1", "");
  c1->SetGrid();

  //tree->Draw("DST.SQHitVector.@_vector.size()", "");
  //c1->SaveAs("n_hits.png");

  tree->Draw("hit.get_tdc_time()",
             "event._trigger == 0x4 && hit.get_detector_id() == 13");
  c1->SaveAs("tdc_time.png");

  tree->Draw("hit.get_element_id()",
             "event._trigger == 0x4 && hit.get_detector_id() == 13");
  c1->SaveAs("ele_id.png");

  exit(0);
}

TTree* GetTree(const int run)
{
  ostringstream oss;
  oss << "/data2/e1039/dst/run_" << setfill('0') << setw(6) << run << "_spin.root";
  string fn_in = oss.str();
  cout << "DST = " << fn_in << endl;
  TFile* file = new TFile(fn_in.c_str());
  if (! file->IsOpen()) {
    cout << "  Cannot open the DST file.  Abort." << endl;
    exit(1);
  }
  TTree* tree = (TTree*)file->Get("T");
  if (! tree) {
    cout << "  Cannot get the tree object.  Abort." << endl;
    exit(1);
  }
  return tree;
}

void PrintTreeElements(TTree* tree)
{
  TObjArray* arr = tree->GetListOfLeaves();
  int n_ent = arr->GetEntries();
  for (int i_ent = 0; i_ent < n_ent; i_ent++) {
    TObject* obj = arr->At(i_ent);
    cout << setw(2) << i_ent << " " << obj->ClassName() << " " << obj->GetName() << "\n";
  }
  cout << endl;
  
  //TLeaf* leaf = tree->GetLeaf("DST.SQHitVector._vector");
  //leaf->Print();
  //TObject* cl = leaf->GetValuePointer();
  //cout << leaf->GetTypeName() << " " << cl->GetName() << endl;
  //leaf->PrintValue(10);
  //exit(0);
}