[ROOT] Adding TString selection capabilities to the Tree->Draw command

From: Malcolm Davidson (davidson@cesbio.cnes.fr)
Date: Tue Jan 30 2001 - 18:45:34 MET 

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Hi Rene,

Thanks for your reply but I'm afraid I didn't express the root of the problem clearly.

What I actually wanted to ask is whether a cut could be made with the draw command

using a branch containing strings. As an example:

I have a tree T containing two branches one labelled "rms" and contaning floats and the other

labeled "field" and containing strings, then it would be nice to be able to plot a histogram of

all values having field == "Field1" with the commands

TString field_cut = "Field1"

T->Draw("rms","field == field_cut");

Even better of course would be the ability to use REGEXPs :) but I would be happy if the first

case was already implemented.

Kind regards

Malcolm

>Hi Malcom,
>There are two TTree::Draw functions:

>Draw(const char* varexp, TCut selection, Option_t* option, ...
> Draw(const char* varexp, const char* selection, Option_t* option,...)

>What you request with TString is implemented with TCut.

>Rene Brun

Malcolm Davidson wrote:
>
> Hello,
>
> I was wondering if the selection based on TStrings for the TTree->Draw()
> command had been implemented yet (based on my attempts not) or whether
> this useful feature (here I'm quoting from a 1999 email from Rene Brun)
> will soon be added ?
>
> Many thanks in advance
>
> Malcolm
> <>------------------------------------------------<>
> Malcolm W. J. Davidson
>
> Centre D'Etudes Spatiales de la Biosphere (CESBIO)
> UMR 5639 CNES-CNRS-UPS
> 18, Avenue Edouard Belin
> F-31401 Toulouse Cedex 4
> FRANCE
>
> e-mail : davidson@cesbio.cnes.fr
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