Hi Ilya,
Here is a macro illustrating how to draw axis in various formats.
Look at the comments at the end.
Rene Brun
{
gROOT.Reset();
c1 = new TCanvas("c1","Examples of Gaxis",10,10,700,500);
c1->Range(-10,-1,10,1);
TGaxis *axis1 = new TGaxis(-4.5,-0.2,5.5,-0.2,-6,8,510,"");
axis1->SetName("axis1");
axis1->Draw();
TGaxis *axis2 = new TGaxis(-4.5,0.2,5.5,0.2,0.001,10000,510,"G");
axis2->SetName("axis2");
axis2->Draw();
TGaxis *axis3 = new TGaxis(-9,-0.8,-9,0.8,-8,8,50510,"");
axis3->SetName("axis3");
axis3->Draw();
TGaxis *axis4 = new TGaxis(-7,-0.8,-7,0.8,1,10000,50510,"G");
axis4->SetName("axis4");
axis4->Draw();
TGaxis *axis5 = new TGaxis(-4.5,-0.6,5.5,-0.6,1.2,1.32,80506,"-+");
axis5->SetName("axis5");
axis5->SetLabelSize(0.03);
axis5->SetTextFont(72);
axis5->SetLabelOffset(0.025);
axis5->Draw();
TGaxis *axis6 = new TGaxis(-4.5,0.6,5.5,0.6,100,900,50510,"-");
axis6->SetName("axis6");
axis6->Draw();
TGaxis *axis7 = new TGaxis(8,-0.8,8,0.8,0,9000,50510,"+L");
axis7->SetName("axis7");
axis7->SetLabelOffset(0.01);
axis7->Draw();
//one can make axis going top->bottom. However because of a long
standing
//problem, the two x values should not be equal
TGaxis *axis8 = new TGaxis(6.5,0.8,6.499,-0.8,0,90,50510,"-");
axis8->SetName("axis8");
axis8->Draw();
}
Ilya Goz wrote:
>
> Hello,
>
> I need to make TGaxis with values running top-down, where
> minimum value is on top, i.e.
>
> 0 |-
> 500 |-
> 1000 |-
> 1500 |-
> 2000 |-
> 2500 |-
>
> Following macro doesn't work as (perhaps naively) expected:
>
> {
> gROOT->Reset();
> TCanvas *c = new TCanvas("c", "Axis test", 2);
> c->Range(-500,0,500,1000);
> TGaxis *goodAxis = new TGaxis(-300, 100, -300, 900, 500, 2500, 512, "", 50);
> // this doesn't work
> TGaxis *badAxis = new TGaxis(300, 100, 300, 900, 2500, 500, 512, "", 50);
> // neither do this
> TGaxis *badAxis2 = new TGaxis(0, 900, 0, 100, 500, 2500, 512, "", 50);
> goodAxis->Draw();
> badAxis->Draw();
> badAxis2->Draw();
> c->Update();
> }
>
> Thank you.
> Ilya V. Goz
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