Hi all, I'm trying to project a TNtuple in to a pre-define TH1F from a c++ code. I Have seen on roottalk some references to this issue, but It seems it doesn't work for me : I define a TH1F* RES : TH1F* RES; RES = new TH1F("DEDT",title,120,-0.1,0.6); ... I read a TNtuple from file : TNtuple *FromFile; FromFile = (TNtuple*) TF->Get("Neutral_Events"); FromFile->Project("DEDT","MSMass",cut,"goff"); ... when I visualize DEDT , it's empty. I tryed the Draw solution : > TH1F *h1 = new TH1F(.. > > The TTree::Draw function (in the form "m>>+h1") fills an histogram > with the name "h1". In your case h1 is the name of the pointer, > not the name of the histogram ("blat"). > It is a good practice to have the pointer_name = histogram_name. > Your program will work with: > TH1F *h1 = new TH1F("blat", "quat", 20, 4.5, 6); > ntuple->Draw("m>>+blat", "(4.5<m)&&(m<6.0)"); > h1->Draw(); > or > TH1F *blat = new TH1F("blat", "quat", 20, 4.5, 6); > ntuple->Draw("m>>+blat", "(4.5<m)&&(m<6.0)"); > blat->Draw(); > > Rene Brun But It doesn't recognise the "goff" option and try to open a canvas from a batch job. And the final result is an empty histogram. In interactive root (on HP), Project(...) doesn't seems to work, however the Draw solution does. Any suggestions ? thanks Pascal
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