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

From: Rene Brun (Rene.Brun@cern.ch)
Date: Thu Apr 29 2004 - 13:52:33 MEST 

Drew,

Three ways, assuming Myclass.h and Myclass.C

1- you have a TChain chain object
   root > .L Myclass.C
   root > Myclass a(&chain)
   root > a.Loop()
   root > chain.Delete()Drew Alton wrote:

2- you have a pointer to a TChain* chain
   root > .L Myclass.C
   root > Myclass a(chain)
   root > a.Loop()
   root > delete chain;

3- you have to use the chain definitions as it was when you ran makeClass
   root > .L Myclass.C
   root > Myclass a
   root > a.Loop()

Rene Brun

 
> Hi,
>    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,
> etc.
>    are you saying I just make a new chain, and I pass it in as &chain?
>                                              -Drew
> 
> 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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