Do something like: TFile *f1 = new TFile("file1.root"); TTree *T1 = (TTree*)f1->Get("t1"); T1->SetLineColor(kRed); T1->Draw("Evis"); TFile *f1 = new TFile("file2.root"); TTree *T2 = (TTree*)f2->Get("T2"); T2->SetLineColor(kBlue); T2->Draw("Evis","some cut","same"); etc By default, the generated histograms has its attrbutes imported from the Tree attributes. You can also use the >>h1 notation then do h1->SetLineColor(kRed). Rene Brun Dennis C. Arrogancia wrote: > > Dear Rene, > > I'll revise my question. I have 4 different files say "file1.root", > "file2.root","file3.root", and "file4.root". Suppose each file contains a > tree "T1". Variables stored in "T1" are Evis, Pt, Pl, etc. I want to > superimpose each of these variables in a histogram for my > background analysis. I need it because i'm formulating a selection > criteria. What i want is for example all the Evis's from each of the 4 > files is superimposed in a histogram, and so on. I want to distinguish > each of them by putting a line color. > > I hope it is clear now. Thank you for your help. > > Dennis > > On Tue, 29 Jan 2002, Rene Brun wrote: > > > Dennis, > > > > It is not completly clear what you want to do. Here is a solution > > to my interpretation of your question: > > > > TChain *MakeChain(const char* name) { > > TChain *chain = new TChain(name); > > chain->AddFile("file1.root"); > > chain->AddFile("file2.root"); > > chain->AddFile("file3.root"); > > chain->AddFile("file4.root"); > > return chain; > > } > > void test() { > > TChain *chain1 = MakeChain("T1"); > > chain1->Draw("x"); > > TChain *chain2 = MakeChain("T2"); > > chain2->Draw("x","","same"); > > TChain *chain3 = MakeChain("T3"); > > chain3->Draw("x","","same"); > > } > > > > Rene Brun > > > > Dennis C. Arrogancia wrote: > > > > > > Dear ROOTERS, > > > > > > I have 4 different files say f1.root, f2.root, f3.root, and f4.root. > > > Each file contains three trees, "T1","T2", and "T3". I want to compare it > > > by superimposing the variables in each of the trees from the 4 files and > > > draw it in a histogram. How can i do it? Can anyone give me an example? > > > > > > dennis > >
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