Thanks, that makes the layout of the data clear.

Now that I've thought about it, I've never seen a polar plot distorted in a way you describe. The polar axis is in decibels, so it already uses logarithmic scale - by "making the outer donuts larger", as you say, you actually want to undo the logarithmic scaling, at least partially. In any case, I see this as a cosmetic alteration that may be harmful, because it changes the shape of the curve you want to show, without good reason.

With that in mind, here is a gnuplot script that produces a graph close to what you want:

set polar
set rr [-40:10]
set rtics 10
unset border
unset xtics 
unset ytics
set grid lt 1 lc rgb "blue"

f(x) = (x+50)**2
g(x) = sqrt(x)-50
set nonlinear r via f(r) inverse g(r)

plot  '/tmp/foo.n2p' u ($0>0&&$0<=361 ? $0*pi/180. : 1/0):1 w l lw 2 n
+otit

[download]

The scaling function (that determines the spacing of the grid circles) is a square function (f(x) in the script) as opposed to exponential. You could use this function in your script if you prefer to stay with your pure perl solution.

In reply to Re^3: Logarithmic Scale by kikuchiyo
in thread Logarithmic Scale by aplonis

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