Copy tree to new file and rename it

Newbie
26

So, the behavior is exactly as intended. The flow is:

  oldfile.GetObject("ntuple", oldtree);
  ...
  auto newtree = oldtree->CloneTree();

where the request is here “explicitly” to slow copy a TTree named “ntuple”, and which has, in the original case and the modified hsimple case, more entries that the AutoSave limit. This means that during the execution of CloneTree a cycle for the TTree named “ntuple” is (of course) created.
Calling TTree::SetObject (better version of SetNameTitle but same result here), will change the name of the live object (and we see that with the name of the key/cycle written by TFile::Write) but will not (and should not) retroactively change the name of the existing cycles in the file. So

  KEY: TNtuple	ntuple;1	Demo ntuple
  KEY: TNtuple	PolSig;1	PolSig

depicts accurately what has happened:

  1. a TNtuple named “ntuple” was auto-saved
  2. a TNtuple named “PolSig” was saved.

To modify the behavior you can change the name of the TNtuple *before* cloning it:

     oldtree->SetObject("PolSig","PolSig");
     auto newtree = oldtree->CloneTree();

*or* avoid the call to AutoSave (and save a lot of time! :slight_smile: ) by using the fast cloning.

  auto newtree = oldtree->CloneTree(-1, "fast");
  newtree->SetObject("PolSig","PolSig");

but still even in that case I would rename the object before cloning.

Cheers,
Philippe.