Re: How to get the histogram in a pad ?

From: Damir Buskulic (buskulic@lapp.in2p3.fr)
Date: Fri Apr 23 1999 - 17:42:47 MEST


Exactly! Except that I don't do exactly the same things once I met a
histogram... oops, a girl...

Cheers

Damir

Rene Brun wrote:
> 
> Hi Damir,
> If I understand correctly your question, you want to do something like
>  "You are going downtown, looking for a nice girl.
>   You do not know her name
>   You do not know where she is
>   The only thing you can do is to be meet with the first nice girl !"
> 
> Translated in Root format, this gives:
>  "you have a directory containing objects, including histograms 1-d,
> 2-d, etc
>  "you want to get say the first object deriving from TH1"
> 
> If the answer is yes, you can use the following loop:
> 
>    TIter next(gDirectory->GetList());
>    TObject *obj;
>    while ((obj = next())) {
>       if (obj->InheritsFrom("TH1")) {
>          return obj; // have found an histogram, return the pointer
>       }
>    }
> 
> Rene Brun
> 
> Damir Buskulic wrote:
> >
> > Hi all,
> >
> > Probably a stupid question that has been answered many times but I can't
> > seem to find it in roottalk
> >
> > Suppose I have an histogram in a pad, without knowing it's name or
> > having a pointer to it. How can I get a pointer to it ? I tried various
> > things such as :
> >
> > * gPad->GetListOfPrimitives()->FindObject(...)    need the name or a
> > pointer to the object, I don't have it
> > * loop on the list of primitives and try to compare with the
> > obj.Class()->Compare(known_histo) but all objects are put in the list as
> > TObjects, so one doesn't know if they are TH1F's or not...
> >
> > All in all, one always needs the name or pointer to the histo. Looping
> > on the list of histograms found in gDirectory is not very handy,
> > especially if one has histograms outside a directory.
> > Well, it should be simple...
> >
> > Cheers
> >
> > Damir
> >
> > --
> > =====================================================================
> > | Damir Buskulic                  | Universite de Savoie/LAPP       |
> > |                                 | Chemin de Bellevue, B.P. 110    |
> > | Tel : +33 (0)450091600          | F-74941 Annecy-le-Vieux Cedex   |
> > | e-mail: buskulic@lapp.in2p3.fr  | FRANCE                          |
> > =====================================================================
> > mailto:buskulic@lapp.in2p3.fr

-- 
=====================================================================
| Damir Buskulic                  | Universite de Savoie/LAPP       |
|                                 | Chemin de Bellevue, B.P. 110    |
| Tel : +33 (0)450091600          | F-74941 Annecy-le-Vieux Cedex   |
| e-mail: buskulic@lapp.in2p3.fr  | FRANCE                          |
=====================================================================
mailto:buskulic@lapp.in2p3.fr



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