Re: [ROOT] Making a chain from a file list.

From: Drew Alton (
Date: Thu Apr 29 2004 - 12:58:15 MEST

   Maybe its' just too early in the morning for me...but I didnt follow
how that would let me change from one list of files to another.
   So yes I have a Myclass.h and Myclass.C set of files.  They were
generated from a chain that included set1_file1.root, set1_file2.root,
etc.  Now I would like to make them use set2_file1.root, set2_file2.root,
   are you saying I just make a new chain, and I pass it in as &chain?

On Thu, 29 Apr 2004, Rene Brun wrote:

> Hi Drew,
> Assuming that you have Myclass.h and Myclass.C (the two files generated
> by MakeClass) and a TChain chain object, do
> root > .L Myclass.C
> root > Myclass a(&chain)
> root > a.Loop()
> root > chain.Delete()
> Rene Brun
> Drew Alton wrote:
> > 
> > Hello,
> >    I am running over a large number of root-tuples and skimming out the
> > events I want to keep.
> >    Given the number of files and events I have I want to keep some
> > separations.
> >    My general plan is to chain a list of files from the same data set,
> > use MakeClass to make a class, which will skim out the ones of interest
> > to me.  Then repeat it for each data set.  Since all the data sets have
> > the same format, the same make class could be used, except that the .h
> > file will have the wrong list of root tuples.  In the past I've just
> > changed this by hand, but it occures to me that it ought to be possible
> > at run time to read a file which contains the list of files to chain
> > together.
> >    Has anyone ever done this...have any examples?
> >    Thanks for the help.
> >                                               -Drew

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