TGraph2D contour with exclusion band

[Majid_Hashemi]

Dear experts,

I have a TGraph2D drawn in cont4z option. Then I want to superimpose another TGraph2D
on the same pad to use one of its contours as the exclusion limit for the first plot.
I know how to put them on two pads, making the second pad transparent and so on.
However, The second TGraph2D is a complicated 2D graph. I have limited the number of contours to 2 by doing g->GetHistogram()->SetContour(2) to get the first contour.
This is fine and it works by showing only one contour superimposed on the background graph on the first pad.
However I want to have hashed style exclusion for the contour so that I show which region of the underlying graph is excluded by the first contour of the second graph on the second transparent pad.
Something like a TCutG but in a more automatic way …

Please give me your comments on how to do it.
I have attached what I want in approximate illustration.
Thanks

_ROOT Version:6.24
_Platform:Kubuntu 20.04
_Compiler:gcc 9.3

---

[dastudillo]

Maybe GetContourList will help you? Once you get the contour as graph, you can draw it with a fill “outside the area” (negative SetLineWidth).

[Majid_Hashemi]

Oh thank you!
That must be the perfect solution.
Thank you so much.
Majid

[Majid_Hashemi]

Hi,
I managed to do it but with some tricks: (pad1 contains the main colorful plot, pad2 contains the exclusion band).
The contour TGraph2D has to be drawn first to fill the contour graphs.
Since I wanted only the graph, I deleted the mother contour plot at the end.
Another point is that gc (exclusion band) shows the hashed exclusion but not the main border line so I cloned it and manipulated the cloned graph to get the red line.

Thanks,
Majid

...
h[type]->Draw("cont list");
 pad2->Update();
  // Get Contours
  TObjArray *conts = (TObjArray*)gROOT->GetListOfSpecials()->FindObject("contours");
  TList* contLevel = NULL;
  TGraph* curv     = NULL;
  TGraph* gc       = NULL;
  TGraph* gcline       = NULL;
  
  contLevel = (TList*)conts->At(1);
  
  // Get first graph from list on curves on this level
  curv = (TGraph*)contLevel->First();
  
  gc = (TGraph*)curv->Clone();
  gcline = (TGraph*)gc->Clone();
  
  gcline->SetLineColor(kRed);
  gcline->SetLineWidth(5);
  gcline->Draw("C");
  gc->SetFillColor(kWhite);
  gc->SetFillStyle(3004);
  gc->SetLineWidth(300);
  gc->DrawClone("C");
  delete(h[type]);

[couet]

@Majid_Hashemi

Another point is that gc (exclusion band) shows the hashed exclusion but not the main border line so I cloned it and manipulated the cloned graph to get the red line.

I am surprise by this. Here is an example where exclusion and border are shown:

{
   const Int_t n = 35;
   Double_t xvalues[n], yvalues[n];
   for (Int_t i=0;i<n;i++) {
     xvalues[i]  = i*0.1;
     yvalues[i] = 10*cos(xvalues[i]);
   }

   auto gr = new TGraph(n,xvalues,yvalues);
   gr->SetLineColor(kBlue);
   gr->SetLineWidth(-2002);
   gr->SetFillStyle(3004);
   gr->SetFillColor(kRed);

   gr->Draw("AC");
}

[Majid_Hashemi]

Oh ok, thanks! It seems to have something to do with the line width.

For me, in a canvas with 4 pads, it is working now with these settings: (gc is the contour from the original 2D graph)

  gc->SetLineColor(kRed);
  gc->SetFillColor(kWhite);
  gc->SetFillStyle(3004);
  gc->SetLineWidth(502);

[dastudillo]

@Majid_Hashemi

gc->SetLineWidth(300);

If you see the link I provided, the last 2 digits are the line width, so you were specifying “no line”.

[Majid_Hashemi]

Exactly! Thanks again!