Re: [ROOT] multiple arrays in TTree::Draw

From: Rene Brun (Rene.Brun@cern.ch)
Date: Wed Jun 20 2001 - 17:01:51 MEST


Hi Volker,
What you want is already there in Root version 3.01.
There are many examples of this type in the documentation.

Rene Brun

On Wed, 20 Jun 2001, Volker Buescher wrote:

> 
> Hi All,
> 
> I keep running into an apparent limitation of the Draw method of TTree,
> and I would appreciate very much any advice on whether this is possible in
> root or whether it could be added in future versions. Here is an example
> of what I'm trying to do:
> I have two branches, each with several variable length arrays,
> e.g. arrays mc_pt[nmc], mc_eta[nmc] in one branch and reco_pt[nreco],
> reco_eta[nreco] in the other branch. Now I'd like to use Draw() on the
> command line to plot for each event a) every entry in mc_pt versus every
> entry in reco_pt and b) same as in a) but apply cuts like
> "abs(mc_eta-reco_eta)<0.1", such that only those pairs of mc_pt/reco_pt
> are plotted, for which that condition is true.
> 
> As far as I understand, root only allows to plot pairs 
> 
> (mc_pt[0],reco_pt[0])
> (mc_pt[1],reco_pt[1])
> (mc_pt[2],reco_pt[2])
> ...
> 
> rather than all possible combinations - did I overlook something? Is there
> a way to do this without the inconvenience of using Loop()? If not,
> would it be possible to add this feature?
> 
> Thanks!
> Volker
> 



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