Hello Rene!
Thank you for your answer.
Rene Brun <brun@pcbrun.cern.ch> writes:
> > I am just starting in using ROOT, and I have some questions in how to
> > organize a TTree.
> If you look carefully at the examples, in particular $ROOTSYS/test/Event,
I did ;-)
> you will see a way to build a Tree with two levels.
Yes, but this is only possible when I try to define the tree with an
Object, what was not my intention here. My question was in how I could
define a "deep" structure without the need to define an TObject.
The reason I need this is that I want to have the name of the branches
and leafs definable at run-time, while tree.Branch(.. &event) has it
fixed on compile-time.
> In general, it does not make sense to go below two levels of containers
> in the data base.
Is there a specific reason for that? I need a structure
event -- detector -- analysis_step -- result
where the people from any "detector" may freely choose the
"analysis_step" name, and anyone developing an "analysis_step" can
define its own (local) result classes with their name. The idea is to
have the results any of these steps in its own separate Root tree and
to "mount" all the trees afterwards.
That's why I thought that I would need a "deeply nested" structure for
the tree, as well as a possibility to have "hierarchical" friends,
t.m. to do a
TFile *EventRootFile = new TFile("EventRoot.root");
TTree *EventTree = (TTree *)EventRootFile->get("root");
TFile *Detector1File = new TFile("Detector1.root");
TTree *Detector1Tree = (TTree *)Detector1File->get("detector1");
//...
EventTree->AddFriend(Detector1Tree, "detector1");
Detector1Tree->AddFriend(Analysis1Tree, "analysis1");
Analysis1Tree->AddFriend(Result1Tree, "result1");
and to request a certain variable as
EventTree->Draw("detector1.analysis1.result1.var");
Is this possible?
> You organize yourself the hierarchy level using class composition.
Can you explain this (or point me to the according documentation)?
> When using a class, the Branch function will automatically build
> the leaves for each data member of the class.
Is there a HOWTO available for this? When I try it myself (Root
version 3.03/07), I always get Error messages:
$ cat MyEvent.h
#include "TTree.h"
class MyEvent {
private:
int MyVar;
public:
int GetMyVar() { return MyVar; }
ClassDef(MyEvent,1)
};
$ rootcint -f EventInt.cpp MyEvent.h
Limitation: Reference member not supported. Please use pointer FILE:/opt/root/include/root/TGenericClassInfo.h LINE:28
Another point is that I always used "#include "root/TTree.h" which rootcint
seems not to understand.
> The TreeViewer does not show the branches/leaves of friend Trees in
> the same pane as the main Tree. This option could be implemented.
That would be *very* nice since it allows an easy "point-and-click"
visualization of a tree together with its friends. How can one ask for
an implementation of this?
Tschuessi
Ole
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