Hi Ray, See TTree::Draw documentation in the following section: // Special functions and variables // =============================== // // Entry$: A TTree::Draw formula can use the special variable Entry$ // to access the entry number being read. For example to draw every // other entry use: // tree.Draw("myvar","Entry$%2==0"); // // Entry$ : return the current entry number (== TTree::GetReadEntry()) // Entries$ : return the total number of entries (== TTree::GetEntries()) // Length$ : return the total number of element of this formula for this // entry (==TTreeFormula::GetNdata()) // Iteration$: return the current iteration over this formula for this // entry (i.e. varies from 0 to Length$). Rene Brun On Fri, 14 Mar 2003, Ray Fliller III wrote: > > > Hello Rooters. > > I have a TTree with a branch that contains an array. I would like to > plot the values of the array vs. the index. > > for example, I have > > Float_t time; > Float_t loss[10]; > > > TTree* foo=new TTree("foo","On You"); > foo->Branch("time",&time,"time/F"); > foo->Branch("loss",&loss,"loss[10]/F"); > > //fill the tree > > In a perfect world I'd like to do > foo->Draw("loss:i"); > and > foo->Draw("loss:i:time"); > > Can you help. I am using ROOT cvs from Monday. > >
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