William J. Deninger wrote: > Hello, > > How do I Draw a "Run_number" histogram in a TTree if I have used the > following to book it? Is there a way similar to TNtuple, that being without > needing to write a bunch of code to sort through the tree and book into a > hist? > > class Event: public TObject > { > EventHeader header; > ...... > } > class EventHeader : public TObject > { > UInt_t Run_number; > ...... > } > > { > Event *event = new Event; > TTree *t = new TTree("tree","example tree"); > tree->Branch("event","Event",&event,32000,0); > for (Int_t i=0; i<100; i++) > { > event->Run_number = i; > t->Fill(); > } > } In an interactive Root session, simply do: Root > tree->Draw("Run_number") I also suggest, you look at the URL: http://root.cern.ch/root/HowtoReadTree.html Rene Brun
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