Re: [ROOT] connect a line to a ntuple scatter plot

From: Rene Brun (Rene.Brun@cern.ch)
Date: Fri Feb 16 2001 - 17:07:34 MET


Hi wei,
This is explained in the doc of TTree::Draw:
   http://root.cern.ch/root/htmldoc/src/TTree.cxx.html#TTree:Draw
Look at section: "How to obtain more info from TTree::Draw"
The example given is the following: assume aTTree/TNtuple ntuple:
 Root > ntuple->Draw("py:px","pz>4");
 Root > TGraph *gr = new TGraph(ntuple->GetSelectedRows(),
                                ntuple->GetV2(), ntuple->GetV1()); 
 Root > gr->Draw("al");

Rene Brun


Xie Wei wrote:
> 
> Dear Rooter
> 
> My question is if there's a very well correlated scatter plot,
> e.g. x:y from a ntuple, how can I draw a line which pass through all the
> points.
> 
> One way to do that is of couse transform this x:y into a 1-D histogram but
> it would be much easier if there's a drawing option in ntuple.
> 
> Thank you !
> --Wei



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