The problem with leading blanks will be fixed. Rene Brun Thomas Kraemerkaemper wrote: > > Rene, > > thanks for your help. While trying out I detected, that leading blanks > of the histogram name are not ignored, e.g. > > ntuple->Draw("some_quantity >>histogram"); > > works as expected, but > > ntuple->Draw("some_quantity >> histogram"); > > does not: In the latter case a new histogram " histogram" is created, > instead of using the predefined histogram "histogram". I guess most > users will regard this as an unwanted feature: leading blanks in > object names should always be skipped. > > Tsch"uss, Thomas Kr"amerk"amper. > > > > > Thomas Kraemerkaemper wrote: > > > > > > > > > I'm still struggeling with this problem (perhaps I didn't understand > > > the ROOT memory/scope concepts; IMO there's a lack of documentation, > > > because I can't figure out that from the WWW pages): > > > > > > I would like to fill one predefined histogram with projections from > > > different TTrees from different files: > > > > > Thomas, > > Sorry for the delay. I am just back to CERN. > > I have slightly modified your macro to save the pointer to the directory > > containing your histogram and to set this directory before > > executing ntuple->Draw > > As you say, this should be better explained in the documentation. > > Rene > > > > { > > gROOT->Reset(); > > Char_t mc_object_name[3]; > > TTree *mc[3]; > > TFile *mc_file[3]; > > TH1F *mc_histo = new TH1F("mc_histo", "MC", 20, 0., 1.); > > TDirectory *homedir = gDirectory; //Save pointer to current directory > > mc_file[0] = new TFile("mc1.root"); > > mc_file[1] = new TFile("mc2.root"); > > mc_file[2] = new TFile("mc3.root"); > > // Files contain TTrees h1 - h3. > > // I can't 'cd' to the files and use h1->Draw("some_quantity >>+ mc_histo"). > > > > // Instead I've tried something like: > > for (Int_t i = 1; i < 2; i++) > > { > > sprintf(mc_object_name, "h%1i", i); > > mc[i] = (TTree *) mc_file[i]->Get(mc_object_name); > > homedir->cd(); //change directory > > mc[i]->Draw("some_quantity >>+mc_histo"); > > } > > > > // And again I got not my histogram filled, but a newly created one: > > mc_histo->Draw(); > > c1->Update(); > > // Is empty... > > } > >
This archive was generated by hypermail 2b29 : Tue Jan 04 2000 - 00:26:20 MET