Gnuplot polar radial axis style

Question

How does one remove or adjust the style of the radial axis line when plotting in polar coordinates using Gnuplot?

Example:

set polar
unset key
unset border
unset tics
plot '' u w filledcurve

Produces:

I want to remove/adjust the horizontal black line.

Answer 1

The command you are looking for is unset raxis, e.g.:

set polar
unset key
unset border
unset tics
unset raxis
set size square
plot 1+cos(t) with filledcurve

I added set size square to use square ratio. The above script results in: