Re: [ROOT] drawing histos with null y-errors

From: Rene Brun (Rene.Brun@cern.ch)
Date: Mon Feb 16 2004 - 09:55:39 MET


David,

I have modified THistPainter to automatically paint with option "hist"
in case all errors are null and the default option is specified.

Rene Brun

David d'Enterria wrote:
> 
> René,
> 
> Rene Brun wrote:
> 
> > Use option "hist". See documentation of TH1::Draw, THistPainter::Paint
> 
> ummh ... is this an "automatic response" message ? of course I can use
> "hist" (see the mail). the docs I'm reading them since 1997...
> probably my mail was not clear enough ...
> people usually expect doing h->Draw() and get something on the screen
> (i.e. the default option="" of TH1::Draw to be "clever" enough to
> display something) if the histo is not empty. I was asking perhaps for a
> modification of THistPainter::Paint(Option_t *option) to plot, by
> default (i.e. when option=""), the histo with "hist" option when the
> errors are null ...
> 
> thanks
> 
> >> I want to plot (for graphical purposes only) a histogram which has
> >> been filled manually and has null y-errors. The default drawing
> >> option for histos in this case produces a "blank" output in the
> >> canvas. An example shows the:
> >>
> >> TH1D* h = new TH1D("h","h",100,0,100);
> >> h->FillRandom("pol1",5000);
> >> h.Draw(); // no problem here the histo has non-null y-errors
> >> for (int i=0;i<h->GetNbinsX()+1;i++){h->SetBinError(i,0.);};
> >> h.Draw(); // the histo "disappears"
> >> h.Draw("h"); // OK the histo is back there ...
> >>
> >> Is this is a bug or a feature ? Why doesn't THistPainter::Paint
> >> (Option_t *option) set the default (empty) draw option to "h" in this
> >> case ?
> >>
> >> Thanks.
> >>
> >> PS: Using root_v4.00.01.Linux.RH7.3.gcc296 binaries (same feature in
> >> root_v3.10.01.Linux.RH7.3.gcc296)
> >
> --
>  David d'Enterria                         Nevis Labs, Columbia University
>  http://www.nevis.columbia.edu/~denterria      538 W. 120th St., NY 10027
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