Scatter Plot with Colorbar

[couet]

void scatter()
{
   auto canvas = new TCanvas();
   gStyle->SetPalette(kRainBow, 0, 0.5); // define a transparent palette


   const int n = 100;
   double x[n];
   double y[n];
   double c[n];
   double s[n];

   // Define four random data set
   auto r  = new TRandom();
   for (int i=0; i<n; i++) {
      x[i] = 100*r->Rndm(i);
      y[i] = 200*r->Rndm(i);
      c[i] = 300*r->Rndm(i);
      s[i] = 400*r->Rndm(i);
   }

   auto scat = new TScatter(n, x, y,c,s);
   scat->SetMarkerStyle(20);
   scat->SetMarkerColor(kRed);
   scat->SetTitle("Scatter plot;X;Y");
   scat->Draw("A");
   canvas->Modified();
   canvas->Update();
   TPaletteAxis *palette = (TPaletteAxis*)scat->GetGraph()->GetListOfFunctions()->FindObject("palette");
   palette->SetX1NDC(0.86);
   palette->SetX2NDC(0.90);
   palette->SetTitle("Palette Title");
   canvas->Modified();
   canvas->Update();
}