Re: [ROOT] Length of axis divisions

From: Olivier Couet (Olivier.Couet@cern.ch)
Date: Wed Mar 17 2004 - 18:04:40 MET


Hello,

 The way to do it would be:

   gr->GetHistogram()->SetAxisRange(0, 360, "X");   
   gr->GetHistogram()->SetAxisRange(0, 200, "Y");
   gr->GetXaxis()->SetNdivisions(-504);    

 a negative number of divisions meaning that the divisions should not be 
optimize. But doing that I do not get exactly 360 as upper limit... 
That's weird ... I'll investigate.

 Olivier                                 


On Wed, 17 Mar 2004, Andreas Zoglauer wrote:

> 
> Hello,
> 
> This probably a really simple question, but I have not found anything 
> helpful in the documentation...
> 
> 
> I have a graph whose x-axis ranges from 0° to 360°.
> Thus a wanted to divide the x-axis in a way, that it shows the ticks 0, 
> 90, 180, 270 and 360.
> 
> How do I do this?
> I tried it with SetNdivisions but this only gives me the ticks at 100, 
> 200 and 300..
> 
> 
> Here is my example macro:
> 
> void Ticks()
> {
>    gROOT->Reset();
>    TCanvas* c1 = new TCanvas("c1","Modulation");
> 
>    int NPoints = 360;
>    TGraph* gr = new TGraph(NPoints);
> 
>    for (int i = 0; i < NPoints; ++i) {
>      double x = i*360.0/NPoints;
>      double y = 100 + 50*cos(2*x*TMath::Pi()/180);
>      gr->SetPoint(i, x, y);
>    }
> 
>    gr->Draw("AC");
>    c1->Update();
> 
>    gr->GetHistogram()->SetXTitle("Azimuthal scatter angle");
>    gr->GetHistogram()->SetYTitle("Counts");
>    gr->GetHistogram()->SetAxisRange(0, 360, "X");
>    gr->GetHistogram()->SetAxisRange(0, 200, "Y");
>    gr->GetHistogram()->SetNdivisions(504, "X");
>    c1->Modified();
> }
> 
> Thanks,
> Andreas
> 
> 
> 
> 

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