Cloning a Tree

Axel Schwank (schwank@mail.desy.de)
Wed, 26 Aug 1998 19:12:50 +0200

Dear ROOT developers,
I wanted to provide you with an example Tree to show problmes in the limit
estimation of TTree::Draw(). Therefore, I wanted to copy the Tree, but
only some branches of it. But I wasn't even able to clone the Tree.
I did

TFile *f = new TFile("SomeFile.root"); // contains a Tree named "T"
TTree *T = (TTree*)f->Get("T");
TTree *T2 = new TTree("T2","Limit estimation test");
T2 = T->CloneTree();

**** Break **** Segmentation fault ******

Is this correct in principle?
I tried with and without loading my shared lib.

Well, anyway, how do I best copy only selected Branches of a Tree?
I thought
1) Connecting a file and retrieving the Tree
2) control the active brances with TTree::SetBranchStatus()
3) clone the Tree to another one

Does TTree::Clone() respect the list of active branches?

I could provide you with the full Tree, but the size is 34MB.
But if I made no error in the above commands, it looks like that's the
only way. Then you could also have a look why the Tree doesn't want to be
cloned.

Thank you in advance,
Axel

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Axel Schwank

DESY H1-F22
Notkestrasse 85
D-22607 Hamburg

Rm. 1b/269
Tel (+49 40) 8998-3560
Fax (+49 40) 8998-4385

e-mail schwank@mail.desy.de
Quix 0165-6-2705109

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