Jonathan, see documentation of TTree::Draw http://root.cern.ch/root/htmldoc/TTree.html#TTree:Draw it says: varexp is an expression of the general form - "e1" produces a 1-d histogram of expression "e1" - "e1:e2" produces a 2-d histogram (or profile) of "e1" versus "e2" - "e1:e2:e3" produces a 3-d scatter-plot of "e1" versus "e2" versus "e3" - "e1:e2:e3:e4" produces a 3-d scatter-plot of "e1" versus "e2" versus "e3" and "e4" mapped on the color number. Rene Brun On Mon, 20 Oct 2003, Johnathan Wang wrote: > Hi, I've the following piece of code which draws an ntuple under a > condition. However, if one looks at the plot, one would notice that it's > the z variable, not the x variable, that's constrained according to the > cut. Is this a bug? If so, would you fix it? > Thank you so much > john > > { > gROOT->Reset(); > > TCanvas *canvas = new TCanvas("canvas","foo",200,10,700,780); > TNtuple *ntuple = new TNtuple("ntuple", "data from ascii file", > "x:y:z:v"); > ntuple->ReadFile ("foo"); > > ntuple->Draw ("x:y:z:v", "x < .1 && x > -.1"); > > TH1F *htemp = (TH1F*)gPad->GetPrimitive("htemp"); > htemp->SetXTitle("x"); > htemp->SetYTitle("y"); > htemp->SetZTitle("z"); > } >
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