Re: [ROOT] Drawing multiple times to same temp histogram

From: Rene Brun (Rene.Brun@cern.ch)
Date: Wed Mar 27 2002 - 08:33:43 MET


Hi Vuko,

Give a different name to each of your histograms.
In your case, t1->Draw will delete the previous histogram named "srhist"
and your pointers in srhistos[] will be dangling pointers.

Rene Brun

On Tue, 26 Mar 2002, Vuko Brigljevic wrote:

> Hi all,
> 
> The following is done using root 3.02/07 on SunOS,
> I see the same problem on Linux.
> 
> I am trying to use the same 2D histo several times in a row
> as output of a Tree->Draw() and I am crashing. The code:
> 
> 
>   TH2F *srhistos[10];
>   
>   int ilay;
>   for (ilay=0; ilay<4; ilay++) {
>     t1->Draw(scalerName(ilay+1)+":time >> srhist",cutString);
>     srhistos[ilay]= new TH2F(*srhist);
>     srhistos[ilay]->GetXaxis()->SetTimeDisplay(1);  
>     srhistos[ilay]->GetXaxis()->SetTimeFormat("%d/%m");  
>     srhistos[ilay]->Draw();
>     gPad->SaveAs(TString(prefix+"singles-layer"+ilay+".eps"));  
>     //    srhist.Reset();     tried this as well: does not help
>     delete srhist;
>   }
> 
> Whether I am deleting the temporary histogram (srhist),
> resetting it or doing neither of both, I am always
> crashing with the following output:
> 
> Info in <TPad::Print>: PostScript file lastDays/singles-layer1.eps has
> been created
> 
>  *** Break *** segmentation violation
> Root > Function makePlots() busy flag cleared
> Function doPlots() busy flag cleared
> 
> How am I supposed to do something like that?
> 
> Thanks for any help!
> 
> Vuko
> 
> 
> ========================================================================
>  Vuko Brigljevic                        | Mail : SLAC, Mail Stop 41
>  Lawrence Livermore National Laboratory |        P.O. Box 4349, Stanford
>  Nuclear and Particle Physics Division  |        CA 94309, USA
>                                         | SLAC-Office : B280- room 143
>  Member of the BaBar Collaboration      | Phone : +1-650-926 8512
>  <vuko@slac.stanford.edu>          <http://www.slac.stanford.edu/~vuko>  
> ========================================================================
> 



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