Hi Mike, There is, may be, something that I miss in your description, but it looks to me that you are trying to use Trees where Trees should not be used. There is a simpler solution to your problem. Do you have only one or a few runs per Root file ? If yes, use a normal Root directory to store your meta information objects such as your few hundred histograms. You will be able to inspect/browse your histograms directly with the root browser. Also this gives the possibility to retrieve one histogram at the time from the directory. Rene Brun Mike Kordosky wrote: > > Hi, > > I am using TTree to basically reorgaize some prexisting data collected in > a PMT testing station (for MINOS). The basic testing entity is known as a > Run. Each run contains some meta information (run number, testing mode, > temperatures, etc) as well as a couple of hundred TH1F (data is binned on > the fly by an automated DAQ). My strategy has been to store the > histograms in a TObjArray (TClonesArray is not possible, even with no > splitting, correct?). I also construct an associated TClonesArray in > parallel with the TObjArray of histograms. Each entry of the clonesarray > is an object HistRef which encapsulates information about an associated > entry of the TObjArray. HistRef contains an integer index which acts as a > psuedo pointer between the two. > > My questions are the following: > > (1) People who use TTrees: Does this sound reasonable? The TObjArray can > be rather long (600+ TH1F). If I want to access 1 histogram, I basically > have to load the whole array in from the TTree, right? If I could use > TClonesArray would that still be the case? I could split up the TObjArray > into a few different branches, based on histogram type. The problem with > that is (a) for some runs, not all branches would be filled. (b) Adding > new histogram types would require adding more branches. Analysis code > would probably break in this case. I am not sure how serious (a) is? > > (2) When filling this tree, I periodically get the following error: > > R__zip: source buffer too big > > This error doesn't happen for every run (TTree entry) and doesn't > correlate with the size of the run in any noticable way. How can I > understand and deal with this message. My tree filling program doesn't > terminate when this happens. > > I am running ROOTv3.00/06 on a Compaq AlphaStation xP900 running RedHat > 6.2 with egcs-2.91.66. > > Sorry for being so long winded! > Thanks, > > Mike Kordosky
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