RE: TChain -> Merge()

From: Giovanni Franzoni <franzoni_at_mail.cern.ch>
Date: Sat, 19 Feb 2005 00:34:18 +0100 (CET)

On Fri, 18 Feb 2005, Philippe Canal wrote:

> Hi,
>
> Can you provide me with a way to reproduce this problem?
>
> Philippe.
>

Hi Philippe, thanks for your reply.
Sure I can.

Here:
/afs/cern.ch/user/f/franzoni/public/Root_Merge you find:

Merge_test_1.root
Merge_test_2.root
Merge_test_3.root which 

which are used as sample files to be merged into Merge_Test_All.root.

/afs/cern.ch/user/f/franzoni/public/Root_Merge/try_Merge.C (which I report here after)
is the little macro that should merge the three trees. v4.02.00/rh73_gcc296/

                Thanks and good evening, Giovanni

/afs/cern.ch/user/f/franzoni/public/Root_Merge/try_Merge.C: {

TFile * FileToWriteFinal = new TFile("Merge_Test_All.root","RECREATE");

TChain* m_The_Chain = new TChain("T1"); m_The_Chain -> Add("Merge_test_*.root"); m_The_Chain->Print();

FileToWriteFinal         -> cd();
FileToWriteFinal         -> SetCompressionLevel(9);

//m_The_Chain->Merge(FileToWriteFinal,1001,"C"); m_The_Chain->Merge("Merge_Test_All.root");

}

> -----Original Message-----
> From: owner-roottalk_at_pcroot.cern.ch [mailto:owner-roottalk_at_pcroot.cern.ch]
> On Behalf Of Giovanni Franzoni
> Sent: Friday, February 18, 2005 10:40 AM
> To: roottalk
> Subject: [ROOT] TChain -> Merge()
>
> Hi Rooters,
>
> I am trying to merge trees of the same kind which sit in different
> (smaller) files into one.
>
> Sorry, I know this issue has already been proposed in the past but I was
> not able to find the reply to noeding (<merging root files>, Fri May 28,
> 2004 14:04).
>
> I use a TChain and:
>
> m_The_Chain->Merge(FileToWriteFinal,100000,"C");
>
> crashes, while
>
> m_The_Chain->Merge("AllTheTrees.root");
>
> gives me a final file whose size is roughly one hundred times bigger than
> the sum of the initial smaller files.
> I have tried both with uncompressed and compressed (level 9 files).
> I tried with several releases, for instance v4.02.00/rh73_gcc296/.
>
> What am I doing wrong?
>
> Thanks, regards, Giovanni
>
>

-- 
Received on Sat Feb 19 2005 - 00:34:22 MET

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