Re: Two hists on top of each other

From: Rene Brun (Rene.Brun@cern.ch)
Date: Thu Nov 18 1999 - 10:15:48 MET


Hi Gerco,
You will find below an example of macro showing a possible solution.
It will part of the tutorials section.

Rene Brun

void two()
{
   //example of macro illustrating how to superimpose two histograms
   //with different scales in the "same" pad.
      
   TCanvas *c1 = new TCanvas("c1","example of two overlapping
pads",600,400);

   //create/fill draw h1
   gStyle->SetOptStat(kFALSE);
   TH1F *h1 = new TH1F("h1","my histogram",100,-3,3);
   Int_t i;
   for (i=0;i<10000;i++) h1->Fill(gRandom->Gaus(0,1));
   h1->Draw();
   c1->Update();  
    
   //create hint1 filled with the bins integral of h1
   TH1F *hint1 = new TH1F("hint1","h1 bins integral",100,-3,3);
   Float_t sum = 0;
   for (i=1;i<=100;i++) {
      sum += h1->GetBinContent(i); 
      hint1->SetBinContent(i,sum);
   }

   //scale hint1 to the pad coordinates
   Float_t rightmax = 1.1*hint1->GetMaximum();
   Float_t scale = gPad->GetUymax()/rightmax;
   hint1->SetLineColor(kRed);
   hint1->Scale(scale);
   hint1->Draw("same");
   
   //draw an axis on the right side
   TGaxis *axis = new TGaxis(gPad->GetUxmax(),gPad->GetUymin(),
         gPad->GetUxmax(), gPad->GetUymax(),0,rightmax,510,"+L");
   axis->SetLineColor(kRed);
   axis->SetTextColor(kRed);
   axis->Draw();
}


Gerco Onderwater wrote:
> 
> Hi Rooters,
> 
> Probably this is somewhere in the tutorials, but I haven't been able to
> find where.
> 
> What I would like to do is plot two TH1D's with the same x-axes,
> but with different y-axes on top of each other. One of the two should then
> refer to the left y-axis and the other to the right one (which should also
> have ticks and a title of course). How do I do that?
> 
> Thanks,
> 
> -- Gerco
> 
> Dr. C.J.G. Onderwater
> Nuclear Physics Laboratory
> 312 Loomis Laboratory of Physics
> University of Illinois at Urbana-Champaign
> 1110 West Green Street
> Urbana, IL 61801-3080
> Phone : (217) 244-7363
> Fax   : (217) 333-1215
> E-mail: onderwat@uiuc.edu



This archive was generated by hypermail 2b29 : Tue Jan 04 2000 - 00:43:43 MET