TH2 polar plot problem

Newbie
1

hi dear expert,
I have a problem with TH2 for polar drawing.
I draw TH2D with pol surf2 C options and got this :

unnamed
unnamed1526×812 7.48 KB

I don’t know why there is a white circle at the center.
if it is drawn with pol lego2 C options there will not be a white circle at the center.
histogram was defined as:

new TH2D(“2d_PrimaryedepKernels”, “2d_PrimaryedepKernels”, 96, 0, 96, 24, 0, 24)

and filled by Monte Carlo simulation.
how can fix it?
I attached .root and plot.c file.

result.root (109.3 KB)
plot.c (30.9 KB)

many thanks,

2

Because the SURF options work with the bin centers. You see the same “margin” without option POL on all the SURF plots.

1 Like
3

hi couet,
thank you for your reply,

so how can i plot it without losing data around the center?
i want to see those countors like the above picture, using lego option is not what i want

many thanks

4

The data are not lost. They surface goes trough the bin center. So you get this margin autos in cartesian (that’s not a margin)

Screenshot 2021-07-08 at 17.13.05
Screenshot 2021-07-08 at 17.13.052042×1434 324 KB

1 Like
5

thank you,
data are not lost, I was wrong.
TH2’s x bins represent cone angles, from 0 to 48 (0 to 180 degrees) these make a sphere, and y bins represent radius, these bins contain values I want to draw these values as contour(isolines).

the first picture that i sent show isoline very well but there is a white circle,

is there any method to draw isoline (contour) by using these data?

6

Have look at the CONT options.

1 Like
7

thank you couet,
i found that my data needs a logarithm scale when reading your article here The Rainbow Color Map - ROOT

so i got this

unna
unna1526×812 28.8 KB

there are many differences between two pictures from the same data, in my case logarithm scale is better because there are a wide range of values.

is there a way to remove the grid that appears with the lego option?
is it possible to plot it with contour lines?

8

Here you can read:

“LEGO3” Draw a lego plot with hidden surface removal, like LEGO1 but the border lines of each lego-bar are not drawn.

No, LEGO plots are not contour plots.

1 Like