Hello,

I am trying to follow your suggestions and produce a 2D histogram with the two variables radius and angles, drawn in polar coordinates. Since my data shows angular symmetry and only radial dependence, I have to draw a histogram with concentric rings of given thickness different colours showing the filling radial gradient.

So I have

U233_xy=new TH2F(“U233_xy”, “U233_xy”, 60, 0., 60., 1, 0., 360.);

U233_xy->Fill(radius, angle); // where radius>0 & radius< 60 and the angle is between 0 and 360

Due to the angular symmetry of the problem I have only one bin in angle, i.e. each ring of radius r is one bin in the 2D histogram

But drawing in polar coordinates

U233_xy->Draw(“lego2 pol”);

shows a chart with bins divided in angle and not radius.

So I decided to swap the radius and angle:

U233_xy=new TH2F(“U233_xy”, “U233_xy”, 1, 0., 360., 60, 0., 60.);

U233_xy->Fill(angle,radius);

but now

U233_xy->Draw(“lego2 pol”);

gives

Error in TView3D::FindPhiSectors: something strange: num. of critical sector not equal 2

^C

*** Break *** keyboard interrupt :0:

^C

*** Break *** keyboard interrupt

Root > *** Interpreter error recovered ***

Error in TView3D::FindPhiSectors: something strange: num. of critical sector not equal 2

I would be very grateful for any suggestions on drawing the “concentric rings” histogram.

Thank you very much,

Best regards,

Cristian