Hi Martin,
Martin Turner wrote:
>
> Hello! does anyone know the answers to the following:
>
> 1) Open an existing root file containing a tree with a single branch in a
> completely different file to the one it was made(easy). Then add
> additional variables to this branch which are simple doubles and ints
> without overwriting the original branch. If this is possible, are the
> additional variables stored at the entry number where it finished last
> time or start from scratch.
> If (1) is impossible then I may fill the tree with dummy
> leaves so that I simply update vertically.
The solution is to use Tree Friends.
See TTree::AddFriend
http://root.cern.ch/root/htmldoc/TTree.html#TTree:AddFriend
See example with $ROOTSYS/tutorials/tree3.C
> 2) Could someone give an example of how to append entry's to a tree.
TFile *f = new TFile("myexistingfile.root","update");
TTree *T = (TTree*)f->Get("myTree");
T->SetBranchAddress(....
your loop with
T->Fill();
T->Write();
Rene Brun
>
> Thanks in advance
> Martin.
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