Re: TChain Entry$

From: Rene Brun <Rene.Brun_at_cern.ch>
Date: Wed, 16 Dec 2009 11:56:40 +0100

Hi Nicolas,

Which version are you using? entry$ should be the chain entry number in your case.
The doc of TTree::Draw says:

   //  Entry$:  A TTree::Draw formula can use the special variable Entry$
   //  to access the entry number being read.  For example to draw every
   //  other entry use:
   //    tree.Draw("myvar","Entry$%2==0");
   //
   //  Entry$      : return the current entry number (== 

TTree::GetReadEntry())

   // LocalEntry$ : return the current entry number in the current tree of a

   //                chain (== GetTree()->GetReadEntry())

Rene Brun

Nicolas Produit wrote:
> Hi,
>
> I want to plot a value in a TChain versus the Entry number in the TChain.
> Problem is that Entry$ is the entry number in a TTree not a TChain.
> Is there a way to have behaviour of Entry$ but refered to the TChain
> not the actual TTree in the loop?
> If I do a TChain::Scan() there is a column named Row that is
> corresponding to what I want but I cannot refer it in a Draw formula.
>
> Thanks
>
>
> ---
> Nicolas Produit
> INTEGRAL Science Data Center Phone: +41 22 379 2140
> 16, Chemin d'Ecogia Fax: +41 22 379 2133
> CH-1290 Versoix www:
> http://isdc.unige.ch/~produit
>
>
>
Received on Wed Dec 16 2009 - 11:55:25 CET