Tree->Draw("var>>hist")

[bellenot]

You can also do:

  for(int nbfile=0; nbfile<nfile; nbfile++){
    for(int nbdir=0; nbdir<ndir; nbdir++){
      hmupt[nbfile][nbdir]->SetLineColor(2+nbfile);
      if (nbfile == 0 && nbdir == 0)
         hmupt[nbfile][nbdir]->Draw("hist");
      else
         hmupt[nbfile][nbdir]->Draw("hist same");
    }
  }

[calbet]

Hi Bellenot,

• yes for nbfile==0 the color is white so I could not see it!
• It works for me too.
• Thank you and Couet for your help!
  Regards

[couet]

I would suggest that you check individually that your histograms are properly filled (doing individual plots one by one) . Remember you have an empty TTree…

[calbet]

Dear Couet,
ok, I’ll do that. Thank you for your help.
Regards