Draw circles on an existing plot.

Usage

circle(
  x,
  y,
  radius,
  nv = 60,
  border = NULL,
  col = NA,
  lty = 1,
  density = NULL,
  angle = 45,
  lwd = 1
)

Arguments

x, y: Coordinates of the center of the circle. If x is a vector of length 2, y is ignored and the center is taken as x[1], x[2].
radius: Radius (or radii) of the circle(s) in user units.
nv: Number of vertices to draw the circle.
border: Color to use for drawing the circumference. polygon
col: Color to use for filling the circle.
lty: Line type for the circumference.
density: Density for patterned fill. See polygon.
angle: Angle of patterned fill. See polygon.
lwd: Line width for the circumference.

Value

Invisibly returns a list with the x and y coordinates of the points on the circumference of the last circle displayed.

Details

Rather than depending on the aspect ratio par("asp") set globally or in the call to plot, circle uses the dimensions of the current plot and the x and y coordinates to draw a circle rather than an ellipse. Of course, if you resize the plot the aspect ratio can change.

This function was copied from draw.circle

Author

Jim Lemon, thanks to David Winsemius for the density and angle args

Examples

plot(1:5,seq(1,10,length=5),
     type="n",xlab="",ylab="",
     main="Test draw.circle")
# draw three concentric circles
circle(2, 4, c(1, 0.66, 0.33),border="purple",
            col=c("#ff00ff","#ff77ff","#ffccff"),lty=1,lwd=1)
# draw some others
circle(2.5, 8, 0.6,border="red",lty=3,lwd=3)
circle(4, 3, 0.7,border="green",col="yellow",lty=1,
            density=5,angle=30,lwd=10)
circle(3.5, 8, 0.8,border="blue",lty=2,lwd=2)