Re: problem with y-scale (a bug?)

From: Hajo Molegraaf <>
Date: Fri, 20 Jan 2006 18:16:54 +0100

Thanks. This works, but one problem is that if I decide to change the y-scale then any other things I changed in the graph (for example an arrow that I added) are deleted/reset.
I added // *MENU* after the declaration of the function SetLimits in hist/inc/TAxis.h and recompiled the source. Now SetLimits shows up in the pop-up menu for the y-axis. Using this I can change the y-scale as I want. But perhaps there are reasons not to do this. Is this bad practice?


>From: Rene Brun <>
>To: Hajo Molegraaf <>
>Subject: Re: [ROOT] problem with y-scale (a bug?)
>Date: Thu, 19 Jan 2006 21:03:13 +0100 (MET)
>When using the TreeViewer you can set the histogram binning in
>the "Histogram" box in the top bar. In your case you can set
> htemp(30,0,300,100,1,1e5)
>Then click on the Draw button
>Rene Brun
>On Thu, 19 Jan 2006, Hajo Molegraaf wrote:
>>I like the TreeViewer for TNtuples that can be lanched from the TBrowser,
>>but the y-range of a plot can not be set properly using the GUI.
>>With the following script I create a root file
>> TFile* file = new TFile("test.root","RECREATE");
>> TNtuple* data = new TNtuple("data","","Temperature:Resistance");
>> double T, R;
>> for( T = 10.0; T < 300.0; T += 1.0 )
>> {
>> R = T*T;
>> data->Fill(T,R);
>> }
>> file->Write();
>> file->Close();
>>I can open this root file in the TBrowser and I can view the TNtuple with
>>the TreeViewer. I drag the Temperature branch to X and the Resistance
>>branch to Y and I click on the button to draw the graph. This creates a
>>nice graph, but I want to have a logaritmic y-scale. So I click on the
>>canvas and choose SetLogy. This changes the y-scale from around 2.5e3 to
>>1e5. Well, I want to see all the data, so I click on the y-axis and select
>>SetRangeUser. I fill in 10 for ufirst and 1e7 for ulast. This changes the
>>y-range from 3e5 to 1e7.
>>How can I change the y-range? I know I can do it with a script using
>>SetLimits, but it seems that using only the GUI it does not work properly.
>>Is it not possible to use SetRangeUser for this? Why does it respond so
>>By the way, is it an idea to add SetLimits to the popup menu for the axis
>>by adding '// *MENU*' to the function SetLimits in include/TAxis.h ?
>>I'm using ROOT Version 5.09/01 16 December 2005, Compiled for linux
>>after downloading the CVS version.
>>Hajo Molegraaf
>>Nieuw op MSN Messenger 7.5: Dynamische achtergronden

Meer ruimte nodig? Maak nu je eigen Space Received on Fri Jan 20 2006 - 18:17:02 MET

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