Re: [ROOT] bug in TChain::Merge?

From: Rene Brun (Rene.Brun@cern.ch)
Date: Mon Jan 13 2003 - 16:29:56 MET


Hi Ken,

You do not indicate which version  you are using,
but I suspect that you use a version older than 3.04/02 where this
problem was fixed.

Rene Brun


On Mon, 13 Jan 2003, Ken Bloom wrote:

> Hi,
> 
> 	I think I've encounted a bug in TChain::Merge.  I've got a large
> number of files, each containing an identically-structured tree, and I want to
> merge the trees into one file.  As it happens, some of the trees have zero
> entries.  (This doesn't bother me; I was running on small chunks of data, and
> throwing away events; it's quite possible that I would have zero entries in an
> individual tree.)  When I try to do the merge, I don't get the right number of
> entries, and it appears that the merge stops at the last file in the chain
> with a non-zero number of entries in the tree.
> 
> 	In looking at the TChain::Merge code, I do see the suspicious line
> 
>       if (GetEntry(i) <= 0) break;
> 
> but I don't know if that is the cause of the problem, as I'm not quite sure 
> what GetEntry does.
> 
> 	Am I right that there is a bug?  Can it be fixed?  I suppose that for 
> now I'll have to comment the empty trees out of my chain.  Thanks, best 
> wishes.
> 
> 						Ken
> 
> 
> ------------------------------------------------------------------------------
> Ken Bloom, Karma Adjuster                                Department of Physics
> 734-763-2329 / 734-936-1817 (fax)                       University of Michigan
> kenbloom@umich.edu                              http://www.umich.edu/~kenbloom
> 



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