RE: Adding variabesl and writing out a tree

From: Snyder, Arthur E. <snyder_at_slac.stanford.edu>
Date: Wed, 18 Jan 2012 14:13:09 -0800

hmmm,, mmm

|SetBranchAddress| is done in the selector |Init| function. The cloned tree and the file it's to go in are created on the 1st call to |process| call. Off hand I don't see how the order can be wrong ..

-Art

---

From: Philippe Canal [pcanal_at_fnal.gov]
Sent: Wednesday, January 18, 2012 2:07 PM To: Snyder, Arthur E.
Cc: roottalk_at_root.cern.ch
Subject: Re: [ROOT] Adding variabesl and writing out a tree

Hi Art,

 > If I create the output |TFile| just before the |CloneTree(0)| I end up with the  > complete original input tree rather than the selected events for which I called new tree |Fill|.

This is unexpected and indicative that there is another problem somewhere.

 > -However when I read the file back in |McSourceId| has not been set to |w|, nor have the other variables I change.

Most likely the call to SetBranchAddress is not done at the right time and/or on the right TTree.

Cheers,
Philippe.

On 1/18/12 12:37 PM, Arthur E. Snyder wrote:
>
> I'm trying to modify some variables and write out some events in my tree, making a reduced sized tree with some useful weights added.
>
> To do this i clone tree, so
>
> pOutputTree=fChain->CloneTree(0);
>
> I change the value of one of the variables
>
> McSourceId=w (re-using a Mc variable not used for data, but there ...)
>
> I fill the tree:
>
> if(pOutputTree!=0) pOutputTree->Fill();
>
> and when |input->Process| is done I write it out:
>
> if(pOutputTree!=0) {
> pOutputFile=new TFile(outputFileName,"create");
> pOutputTree->Write();
> pOutputFile ->Close();
> }
>
> -However when I read the file back in |McSourceId| has not been set to |w|, nor have the other variables I change.
>
> So is there some way to make this work?
>
> -Art S.
>
>
> PS. There is another odd problem. If I create the output |TFile| just before the |CloneTree(0)| I end up with the complete
> original input tree rather than the selected events for which I called new tree |Fill|. So I keep it in memory and open and write
> to TFile only at the end.
>
> I don't think this is related to above problem ...
>
>
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Received on Wed Jan 18 2012 - 23:16:38 CET