# Re: [ROOT] superimposing graphs with different scales

From: Rene Brun (Rene.Brun@cern.ch)
Date: Tue Mar 13 2001 - 19:03:22 MET

```Hi Bernhard,
Possible, but a bit more complex.
Below an example modified from tutorials/gerrors2.C.
It might be simpler to simply scale the second graph.

Rene Brun

{
gROOT->Reset();
c1 = new TCanvas("c1","gerrors2",200,10,700,500);

// draw a frame to define the range
TH1F *hr = c1->DrawFrame(-0.4,0,1.2,12);
hr->SetXTitle("X title");
hr->SetYTitle("Y title");

// create first graph
Int_t n1 = 10;
Double_t x1[]  = {-0.22, 0.05, 0.25, 0.35, 0.5, 0.61,0.7,0.85,0.89,0.95};
Double_t y1[]  = {1,2.9,5.6,7.4,9,9.6,8.7,6.3,4.5,1};
Double_t ex1[] = {.05,.1,.07,.07,.04,.05,.06,.07,.08,.05};
Double_t ey1[] = {.8,.7,.6,.5,.4,.4,.5,.6,.7,.8};
gr1 = new TGraphErrors(n1,x1,y1,ex1,ey1);
gr1->SetMarkerColor(kBlue);
gr1->SetMarkerStyle(21);
gr1->Draw("LP");

// create second graph
Int_t n2 = 10;
Float_t x2[]  = {-0.28, 0.005, 0.19, 0.29, 0.45, 0.56,0.65,0.80,0.90,1.01};
Float_t y2[]  = {0.82,3.86,7,9,10,10.55,9.64,7.26,5.42,2};
Float_t ex2[] = {.04,.12,.08,.06,.05,.04,.07,.06,.08,.04};
Float_t ey2[] = {.6,.8,.7,.4,.3,.3,.4,.5,.6,.7};
for (Int_t i=0;i<n2;i++) {
y2[i] *= 100;
ey2[i] *= 100;
}
c1->cd();
overlay->SetFillStyle(4000);
overlay->SetFillColor(0);
overlay->SetFrameFillStyle(4000);
overlay->Draw();
overlay->cd();
gr2 = new TGraphErrors(n2,x2,y2,ex2,ey2);
gr2->SetMarkerColor(kRed);
gr2->SetMarkerStyle(20);
gr2->SetName("gr2");
Double_t ymin = 0;
Double_t ymax = 1200;
TH1F *hframe = overlay->DrawFrame(xmin,ymin,xmax,ymax);
hframe->GetXaxis()->SetLabelOffset(99);
hframe->GetYaxis()->SetLabelOffset(99);
gr2->Draw("LP");

//Draw an axis on the right side
TGaxis *axis = new TGaxis(xmax,ymin,xmax, ymax,ymin,ymax,510,"+L");
axis->SetLineColor(kRed);
axis->SetLabelColor(kRed);
axis->Draw();

}

Bernhard Ketzer wrote:
>
> Hi Rooters,
>
> how can I superimpose two TGraphs with different y-scales on the same
>
>
> Bernhard
>
> --
> -----------------------------------------------------------------------------
> Bernhard Ketzer                       Tel.: +41 22 76-76002  FAX: -77100
> CERN, EP Division                     GSM : +41 79 201 4404 (CERN
> 164404)
> CH-1211 Geneve 23                     Email: Bernhard.Ketzer@cern.ch
```

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