Re: copy selected entries of subset of chain

From: Eduard Avetisyan <Eduard.Avetisyan_at_desy.de>
Date: Tue, 12 Apr 2011 15:16:32 +0200

Hi Margar,

I used to successfully achieve what you are aiming now via the TTree::CopyTree method. An additional benefit is that you may impose selection cuts to reduce your tree size by stripping useless entries off.

Hope this helps,

        Eduard

P.S. A short example below:

{

   TChain h1("h1");

   h1.Add("../h_hdunpol_00d0.root");
   h1.Add("../h_unpol_00d0.root");
   h1.Add("../../98/h_unpol_98d0.root");

   //Create a new file + a clone of old tree in new file    TFile *newfile = new TFile("h_9800d0" "_pi+.root","recreate");    TTree *newtree = h1.CopyTree("pos>0 && ph>0");

   newtree->SetName("piplus");
   newtree->SetTitle("98/2000 unpol H pi+");
   newtree->Print();
   newfile->Write();

   delete newfile;
}

On Tue, 12 Apr 2011, Philippe Canal wrote:

> Hi Margar,
>
> Then all the ingredients are there and it should work ... unless their
> ordering
> and calls are wrongly set (I would need more code to know).
>
> Cheers,
> Philippe.
>
> On 4/12/11 8:02 AM, Margar Simonyan wrote:
> > Hi Philippe
> >
> > sorry, that was a typo in the e-mail, I have
> > chain->SetBranchStatus("*", 1) in the code, as well as LoadEntry,
> > GetEntry etc.
> >
> > Margar
> >
> >
> >
> > On Tue, Apr 12, 2011 at 2:58 PM, Philippe Canal<pcanal_at_fnal.gov> wrote:
> > > Hi Margar,
> > >
> > > (Besides the missing LoadEntry, GetEntry and SetBranchAddress which I
> > > assume
> > > are in the routines
> > > you did no show), it seems that the problem is the 2nd argument of the 2nd
> > > SetBranchStatus,
> > > I think it should read:
> > >
> > > chain->SetBranchStatus("*", 1);
> > >
> > > Cheers,
> > > Philippe.
> > >
> > > On 4/12/11 2:43 AM, Margar Simonyan wrote:
> > > > Hello ROOTTalk
> > > >
> > > > I would like to copy selected entries of some branches of TChain to
> > > > another tree. So far my attempt work for single tree but not for a
> > > > chain. Simplified logic looks like this:
> > > >
> > > > type var1;
> > > > TBranch * b1=0;
> > > > chain->SetBranchAddress("var1",&var1,&b)
> > > >
> > > > chain->SetBranchStatus("*", 0)
> > > > chain->SetBranchStatus("var1", 1);
> > > >
> > > > f = TFile::Open("file.root", "UPDATE");
> > > > newTree = chain->CloneTree(0);
> > > >
> > > > now have to enable all branches since they are needed for event
> > > > selection
> > > > chain->SetBranchStatus("*", 0);
> > > > for(; ; )
> > > > if(selection_function())
> > > > newTree->Fill()
> > > >
> > > >
> > > > The trees are connected and when a new file is opened in chain things
> > > > go wrong. I tried reseting the branch addresses, but it didn't work.
> > > > Is there any way to get it working?
> > > >
> > > > Thanks,
> > > > Margar
> > > > -------------------------------------------------------------------------
> > > > Dr Margar Simonyan, post-doctoral researcher
> > > > Niels Bohr Institute, Copenhagen University
> > > > -------------------------------------------------------------------------
> > > >
>
>
Received on Tue Apr 12 2011 - 15:16:37 CEST