Re: Nested data structures using TClonesArrays

From: Rene Brun (Rene.Brun@cern.ch)
Date: Thu Dec 02 1999 - 19:00:05 MET


Hi Dave,
You cannot use TClonesArray for this problem. Use TObjArray instead.
TClonesArray assume that the size of each object is constant.
In your case each track has a variable length list of hits.

Rene Brun

On Thu, 2 Dec 1999, David  Bailey (Antares Post Graduate) wrote:

> Hi all,
> 
>   I'm trying to build a data structure in a ROOT file which contains several
> levels of data. i.e.
> 
> header
> events -> calibration
>           tracks      -> track parameters
>                       -> hits             -> position
>                                              amplitude etc
> 
> i.e. Within each "event" there will be many "calibration" events and many
> "tracks" each of which contain many "hits". Essentially, it is like the
> example in the distribution ( class Event and Track ) but with another layer
> ( in that context, "Track" contains a number of "Hits" ). As documented in
> the example "How to Create and Fill a tree", TClonesArrays cannot be used
> except for the last level of data with automatic splitting ( i.e. As I
> understand it, "tracks" will contain a TClonesArray of "hits" ). The
> question is, what is the best structure to use for the levels above and how
> are they implemented?
> 
>  Thanks in advance, Dave Bailey
> 
> /------------------------------------------/
>   David Bailey : Antares post-Graduate    /
>   Nuclear and Astrophysics Laboratory    /
>   Keble Road, Oxford OX1 3RH    /-------/
>   (01865) 273395  /------------/
> -----------------/ d.bailey2@physics.ox.ac.uk
> 



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