Hi, I have an Ntuple NT with fields x, y, ex, ey containing (x,y) points with errors. I want to create a TGraphErrors instance TGE using these points. The easiest way to accomplish this seems to be Float_t *fp = NT->GetArgs(); then use fp and my knowledge of the NT structure to fill four temporary float arrays (let's say tx, ty, tex, tey) with the correct data, and finally to do TGraphErrors *TGE = new TGraphErrors(npoints, tx, ty, tex, tey); Is there a better, more direct way? In other words, is there a way to extract single Ntuple columns into arrays? Please send a cc of the answer directly to my e-mail address (I don't subscribe this mailing list). Thanks in advance! Ville
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