Plot a Grid in Polar Coordinates

PolarGrid adds a polar grid to an existing plot. The number of radial gridlines are set by ntheta and the tangential lines by nr. Labels for the angular grid and the radial axis can be provided.

PolarGrid(nr = NULL, ntheta = NULL, col = "lightgray", lty = "dotted", lwd = par("lwd"),
          rlabels = NULL, alabels = NULL, lblradians = FALSE, cex.lab = 1, las = 1,
          adj = NULL, dist = NULL)

Arguments

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.

Author

Andri Signorell <andri@signorell.net>

See also

PlotPolar

Examples

Canvas(xlim=c(-5,5), xpd=TRUE)
PolarGrid()


Canvas(xlim=c(-5,5), xpd=TRUE)
PolarGrid(nr=0:5, ntheta=6)


Canvas(xlim=c(-5,5), xpd=TRUE)
PolarGrid(ntheta=36, rlabels=NA, lblradians=TRUE)