Hi Andreas, you can use TTree::Project() for this purpose (note that TNtuple is a TTree by inheritance): TH2F* xy = new TH2F("xy_histo","density",nBinsX,xmin,xmax,nBinsY,ymin,ymax); ntuple->Project("xy_histo","y:x"); This asumes that yo have declared and intialised nBinsX etc. to sensible values. cheers, Kurt On Wed, Jul 02, 2003 at 04:34:21PM +0200, Andreas Adelmann wrote: > Hi rooter suppose I have data filled in an > ntuple of the following form: > > TNtuple* ntuple = new > TNtuple("ntuple","NTUPLE","x:px:y:py:z:pz:id:node"); > > and I would like to make a density plot in the x and y > plane. > > How do I fill a histogram from the ntuple? > > Thanks, Andreas > > -- > Andreas (Andy) Adelmann > Paul Scherrer Institut > CH-5232 Villigen PSI > Phone Office: xx41 56 310 42 33 Fax: xx41 56 310 31 91 > Phone Home: xx41 62 891 91 44 -- Kurt Rinnert, University of Karlsruhe (TH) - Faculty for Physics
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