- nr
number of circles. When NULL, as per default, the grid aligns with the tick marks on the corresponding default axis
(i.e., tickmarks as computed by axTicks). When NA, no circular grid lines are drawn.

- ntheta
number of radial grid lines. Defaults to 12 uniformly distributed between 0 and 2*pi (each pi/3).

- col
character or (integer) numeric; color of the grid lines.

- lty
character or (integer) numeric; line type of the grid lines.

- lwd
non-negative numeric giving line width of the grid lines.

- rlabels
the radius labels. Use `NA`

if no labels should be to be added.

- alabels
the labels for the angles, they are printed on a circle outside the plot. Use `NA`

for no angle labels.

- lblradians
logic, defines if angle labels will be in degrees (default) or in radians.

- cex.lab
the character extension for the labels.

- las
alignment of the labels, 1 means horizontal, 2 radial and 3 vertical.

- adj
adjustments for the labels. (Left: 0, Right: 1, Mid: 0.5) The default is 1 for the levels on the right side of the circle, 0 for labels on the left and 0.5 for labels exactly on north on south.

- dist
gives the radius for the labels, in user coordinates. Default is par("usr")[2] * 1.07.