Hi Brett,
You can use TTree::BuildIndex in this case with
tree.BuildIndex("Run","Event") (or any pair of variables in the Tree.
then, when you do#
tree.GetEntryWithIndex(2200,456); this will internally call
TTree::GetEntry with the serial entry number corresponding to Run=2200
and Event=456.
You can alternatively call
Int_t entry = tree.GetEntryNumberWithIndex(2200,456);
tree.GetEntry(entry);
friendtree.GetEntry(entry).
If the entry numbers between two Trees do not correspond, you cannot
use the friend mechanism, but you can still use the technique above,
like:
tree1.BuildIndex("Run","Event"); has N1 entries
tree2.BuildIndex("Run,"Event"); has N2 entries
tree1.GetEntryWithIndex(2200,456)
tree2.GetEntryWithIndex(2200,456);
Rene Brun
On
Fri, 14 Feb 2003, Brett
Viren wrote:
> Hi,
>
> Is there anyway for a TTree to befriend another via entries common to
> each (say, run number + event number)?
>
> -Brett.
>
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