Hi again,
I forgot to mention that I'm using today's cvs version of ROOT compiled w/gcc2.95.3
on rh linux.
-Sue
Susan Kasahara wrote:
> Hi roottalk,
> I have a question about using TRefArray objects in the TTree::Draw
> method.
> In the $ROOTSYS/test/Event example, there is a datamember:
> TRefArray *fHighPt; // array of High Pt tracks only
> in the Event class that is filled with references to a subset of the tracks stored
> in the
> TClonesArray *fTracks; //->array with all tracks
> array.
> After running the executable "Event" to generate an output file Event.root, I am able
> to open this file in a root session and plot datamembers of the fTracks array, e.g.
>
> t -> Draw("fEvtHdr.GetEvtNum()","fTracks[0].GetPx()>0");
>
> works and plots a histogram of event numbers for all events in which the first track
> has a positive Px.
> But if I try to use the fHighPt TRefArray in a similar way,e.g.
> t -> Draw("fEvtHdr.GetEvtNum()","((Track*)fHighPt->At(0))->GetPx()>0");
> I receive the error message:
> Error in <TTreeFormula::DefinedVariable>: Unknown method:At(0).).GetPx()
>
> *ERROR 26 :
> Unknown name : "((Track*)fHighPt.At(0)).GetPx()"
>
> So, I'm wondering, what is the correct way to use the fHighPt branch in the TTree::Draw,
> TTree::Scan, etc.?
>
> Thanks for the help,
> -Sue
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