Re: Duplicated tree

The duplicate Tree has nothing to to with the TChain. You simply get 2 or more versions of the Tree header in the file. The reason is explained in TTree::AutoSave.
Note that only the Tree header has multiple cycles, not the bulk of the tree data.
Could you indicate what is the problem?

Rene Brun

James Jackson wrote:
> Hi Rene,
>
> OK, so this is what's going on. I use these in a chain (I have O(100)
> such output files for each dataset). How can I read these back
> transparently?
>
> Best regards,
> James.
>
> On 22 Apr 2009, at 15:52, Rene Brun wrote:
>
>> see http://root.cern.ch/root/html/TTree.html#TTree:AutoSave
>>
>> Rene Brun
>>
>>
>> James Jackson wrote:
>>> Hi,
>>>
>>> I'm trying to track down a strange problem... I have some common
>>> code, which I run over many datasets, to create and fill some trees.
>>> Each tree is created once, and only once.
>>>
>>> In some instances, the resulting ROOT file has duplicates. The
>>> output should look like this:
>>>
>>> Unknown-00-17-f2-51-00-e3:PhotonJetPt15 jamesjackson$ root -l
>>> output_15.root
>>> root [0]
>>> Attaching file output_15.root as _file0...
>>> root [1] TDirectory *d = _file0.Get("tupiliser")
>>> root [2] d->ls()
>>> TDirectoryFile* tupiliser tupiliser (Tupiliser) folder
>>> KEY: TTree EventData;1 Per event object information
>>> KEY: TTree McElectrons;1 MC Electrons
>>> KEY: TTree HeepElectrons;1 HEEP Electrons
>>> KEY: TTree Tracks;1 Tracks
>>> KEY: TTree SuperClusters;1 SuperClusters
>>> KEY: TTree GenData;1 GenData
>>>
>>> However, sometimes, I get the following:
>>>
>>> Unknown-00-17-f2-51-00-e3:QCDpt30 jamesjackson$ root -l output_1.root
>>> root [0]
>>> Attaching file output_1.root as _file0...
>>> root [1] TDirectory *d = _file0.Get("tupiliser")
>>> root [2] d->ls()
>>> TDirectoryFile* tupiliser tupiliser (Tupiliser) folder
>>> KEY: TTree Tracks;3 Tracks
>>> KEY: TTree Tracks;2 Tracks
>>> KEY: TTree EventData;1 Per event object information
>>> KEY: TTree McElectrons;1 MC Electrons
>>> KEY: TTree HeepElectrons;1 HEEP Electrons
>>> KEY: TTree SuperClusters;1 SuperClusters
>>> KEY: TTree GenData;1 GenData
>>>
>>> Note "Tracks" is duplicated.
>>>
>>> Does this look like anything anyone's seen before? Can anything
>>> trigger a re-creation of a tree during filling?
>>>
>>> Any hints welcome - I can see nothing in my code that would
>>> re-create the tree.
>>>
>>> Regards,
>>> James.
>>>
>>
>
Received on Wed Apr 22 2009 - 17:01:58 CEST