Re: [ROOT] sincronise chains by index?

From: Rene Brun (Rene.Brun@cern.ch)
Date: Tue Jun 19 2001 - 20:34:38 MEST


Hi Valeri,
I had already similar suggestions from a few people during the ROOT
workshop at FNAL. I agree that adding to the current loop by entry number
the possibility to loop via the index built by TTree::BuildIndex
or/and the TEventList machinery would be an interesting upgrade.
As you say, most tools are there to implement this.
Stay tuned.

Rene Brun

On Tue, 19 Jun 2001, Valeri Tioukov wrote:

> Hi Rene and rooters,
> 
> Chains and friends are already a lot for trees organization and
> processing. Logically the trees developing move in direction of relational
> tables. Why do not make one more step and introduce possibility to
> sicnchronise tables by the primary key? It seems that everithing is exists
> already for that. The role of key could play index value. This possibility
> could provide more freedom to the data processing. 
> 
> The typical scenario of data processing could be as:  
> - tree(chain) with headers for example just runID, eventID for all events
> - tree(chain) with raw data 
> - tree(chain) with processed data version1 
> - tree(chain) with processed data version2... 
> - .... 
> 
> As it is now - only if all these chains has the same number and the same
> sequence of entries we can establish the useful friendship. 
> 
> It is not alwais convenient, othen only a small fraction of events are
> interesting for processing. One way, of cause, - to extract useful events
> into the new trees. But it could be avoided if one have runID, eventID
> (naturally!) in each of these trees - them could be indexed, friendship
> established and then sincronised using index values by the standard (new)
> function. 
> 
> What do you think about that? 
> 
> Regards
> Valeri
> 



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