Plotting multiple histos from root file

ROOT
1

Dear Experts,
I am trying to plot in 16 canvases my 256 histograms which I have already stored in root file , subdirectory.
I am getting first 16 histos in first canvas, then next 15 in second, and then my session crashes like in bottom part of my message.
If I don’t draw the histos , the root allows me to plotthem by hand.
Here is my small macro:
Thanks in advance
Avetik

  TFile *f = new TFile("tst337.root");
  f.ls();
  f.cd("TimetoRefChan");
  f->GetListOfKeys()->Print();
//f->cd("subdirectory")
TIter next(gDirectory->GetListOfKeys()); 
//create windows and fill with histograms, save them if filename is not empty
  printf("Drawing histograms...\n");
//AAA f.ls();
  char name2[40];
  char name[40];
  char hname[40];
  TCanvas *c1[16];
  Double_t s=0;
 for(Int_t i=0;i<16;i++)
  {
        sprintf(name,"overview timeDiff  %02d",i);
        c1[i]=new TCanvas(name2,name,1000,1000);
        c1[i]->Divide(4,4);
        for(Int_t j=1;j<=16;j++)
        {
                c1[i]->cd(j);
        sprintf(name2,"TimetoRefChan/TimetoRefChan%02d;1",(j+i*16)-1);
        sprintf(hname,"TimetoRefChan%02d",((j+i*16)-1));
                printf("Name2 = %\s\n",name2);
                printf("hname = %\s\n",hname);
                TH1D *hhh; f->GetObject(name2,hhh);
                hhh->Draw();
        }
}
/////////////////////////////////////////////////////////////////////////////
  printf("done...\n");

}

-----------------------output after plotting histo 31-----------------------------
*** Break *** segmentation violation

===========================================================
There was a crash (#7 0x0076d3ab in SigHandler(ESignals) () from /usr/local/lib/root/libCore.so).
This is the entire stack trace of all threads:

2

I tried to simplify your macro to keep on the “graphics bit”. It works for me. To investigate further we would need your ROOT file in order to run your macro.

3

Dear Oliver,
Thanks for your care, please find attached root file.
This is first time I am posting file in root forum, please let me know if I manage it correctly.
Thanks in advance
Avetik
tst337.root (984 KB)

4

Ok… understood… you could have found it easily … your file does not have the histogram 31…

Here is a cleaned up version of your macro with a protection against none existing histograms:

{
   TFile *f = new TFile("tst337.root");
   f.ls();
   f.cd("TimetoRefChan");
   f->GetListOfKeys()->Print();
   TIter next(gDirectory->GetListOfKeys()); 
   printf("Drawing histograms...\n");
   char name2[40];
   char name[40];
   char hname[40];
   TCanvas *c1[16];
   TH1D *hhh;

   Double_t s=0;
   for (Int_t i=0;i<16;i++) {
      sprintf(name,"overview timeDiff  %02d",i);
      c1[i] = new TCanvas(name,name,1000,1000);
      c1[i]->Divide(4,4);
      for (Int_t j=1;j<=16;j++) {
         c1[i]->cd(j);
         sprintf(name2,"TimetoRefChan/TimetoRefChan%02d;1",(j+i*16)-1);
         sprintf(hname,"TimetoRefChan%02d",((j+i*16)-1));
         printf("name2 = %s hname = %s\n",name2, hname);
         hhh = 0;
         f->GetObject(name2,hhh);
         if (hhh) hhh->Draw();
      }
   }
  printf("done...\n");
}