The selection expression in TTree::Draw returns the weight to be
used when filling the histogram.
If you have a selection expression sel= a && b, the result
will always be 0 or 1. In your case, you should do:
ntuple.Draw("ntracks","(1/w)*(px == 2.)")
or simply
ntuple.Draw("ntracks","(px == 2.)/w")
Rene Brun
On Fri, 3 Mar 2000, Zhou Zhang wrote:
> Hi rooter talkers,
>
> I have a ntuple which holds a lot of tracks with a weight w.
> Each tuple of the track has px,py,pz which are the three momentum
> components of the track.
>
> when I use ntuple.Draw("ntracks","1/w && px == 2. "), the plot looks
> that the normalization cut "1/w" is not applied. Have anyone met such
> problem before? Who could give me some advices to solve it?
>
> Thanks
>
> Zhou
>
>
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