Re: [ROOT] How to get the histogramm after the TChain->Draw method.

From: Stephen Bailey (bailey@physics.harvard.edu)
Date: Mon Nov 20 2000 - 20:57:28 MET


Hi Cyril.

Replace
  TH1F *htemp;
with 
  TH1F *htemp = gROOT->FindObject("htemp");

"htemp" is the name of the histogram out in RootSpace that
you have to get your pointer to point to.  You could have
called your pointer TH1F* hblat if you wanted; the important
part is to get a pointer to what Root named "htemp".
In compiled code, I'm not sure what you need to do (if
anything) to gain access to gROOT, but you need to make
a call to TROOT::FindObject() to get the pointer.

Ciao.

Stephen

On Mon, 20 Nov 2000, Cyril Lachaud wrote:

> 
> Hi again,
> 
> thank you for the answer... but I'm still not satisfied...
> 
> Here is my code:
> 
> fFiles_chained->Draw("variable");
> fHCanvas->Update(); // it gives me the good histogramm : htemp
> TH1F *htemp;
> htemp->SetXTitle("toto");
> 
> The last command gives the following error:
>  *** Break *** segmentation violation 
> 
> If you have the answer...
> 
> Cyril Lachaud.
> 
> 
> On Mon, 20 Nov 2000, Rene Brun wrote:
> 
> > Hi Cyril,
> > 
> > If htemp is in your current pad gPad, from the command line, you can do:
> >  htemp->GetXaxis()->SetTimeDisplay(1);
> >  htemp->GetXaxis()->SetTimeFormat("some format");
> > 
> > Rene Brun
> > 
> > Cyril Lachaud wrote:
> > > 
> > > Hi Rooters,
> > > 
> > > I'm working on a shared library (so not "in line").
> > > 
> > > I would like to know how to access to the histo filled after the
> > > TChain->Draw method... (to modify axis for time format for example).
> > > 
> > > As far as I know this histo is called by default "htemp". But how can I do
> > >  htemp->GetXaxis->SetTimeFormat() ?
> > > 
> > > Thank you.
> > > 
> > >  Cyril Lachaud
> > 
> 



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