Re: [ROOT] Speeding up TTree::Draw()

From: Rene Brun (Rene.Brun@cern.ch)
Date: Fri Apr 05 2002 - 09:50:06 MEST


Hi Martin,

Use MakeClass or MakeSelector if you want to produce many histograms in one go.

Rene Brun

Martin Turner wrote:
> 
> Hello!
> 
> I have a tree which I use to produce a second tree with a
> different number of entries, for example looping over events in the first
> and then tracksxevents in the second. Currently if my histograms take 100
> seconds to make and I want 10 of them then I am waiting 1000 seconds since
> Draw appears to do a seperate loop for each plot. This is much slower than
> sticking to the first tree, do one loop and fill the histograms as you go.
> Is there a neat  way to link histograms together using TTree so that I
> don't have to wait for 10 loops, or is it necessary to use MakeClass?
> 
> Martin



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