Hi,
This feature 'could' be added to the TTree::Draw mechanism but it would not be
trivial.
A better alternative in your case is to use the MakeClass feature
that would give you a much wider range of possibilities to create
and fill your histogram (See TTree::MakeClass).
Philippe.
> -----Original Message-----
> From: owner-roottalk@pcroot.cern.ch
> [mailto:owner-roottalk@pcroot.cern.ch]On Behalf Of Marcelo G. Munhoz
> Sent: Friday, August 11, 2000 12:46 PM
> To: roottalk
> Subject: [ROOT] arrays in TTree
>
>
>
> Hi,
>
> I have a TTree composed of TClonesArray objects (TBranchClones).
> From the documentation (and empirically), I noticed that is possible to
> refer to a specific element of my array using the [ ] operator. So, for
> instance, let's say my TTree has two branchs of TClonesArray called
> clone1 and clone2. The object clone1 has data members a1 and b1, while
> the object clone2 has data members a2 and b2. Now, I can do something
> like:
>
> myTree->Draw("clone1.a1:clone2.a2[2]")
>
> i.e., I can draw all elements a1 from clone1 as a function of the
> specific element a2[2] from clone2. However, that's not exactly what I
> want to do. Instead of drawing always a2[2] in the x-axis, I'd like to
> select the element of a2 with a index given by b1, i.e., b1 is a index
> refering to the TClonesArray clone2. So, what I'd like to do is:
>
> myTree->Draw("clone1.a1:clone2.a2[clone1.b1]")
>
> I've tried this syntax and it does not work. Unless you introduce a
> number between [ ], ROOT totally ignores what is inside.
>
> My question is: is there anyway to go around this limitation? I'd
> like also to use such thing for selection. For instance, to do something
> like:
>
> myTree->Draw("clone1.a1","clone2.a2[clone1.b1]>0")
>
>
> Maybe my problem is too specific, but if someone had similar
> experience, I'd apreciate any help. And I hope my explanation is not too
> confusing...
>
> Thanks for any help,
>
> Marcelo.
>
>
>
>
>
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