berryFunctions (version 1.22.5)

circle: Draw circle with a given radius

Description

Draws a filled circle with a certain radius (in existing plot's units) using polygon and sin

Usage

circle(x, y, r, locnum = 100, ...)

Value

data.frame of coordinates, invisible

Arguments

x

x coordinate of points, numeric value of length 1

y

y coordinate

r

radius of the circle in units of current plot. Can have two values for an ellipse.

locnum

number of calculated points on the circle (more means smoother but slower). DEFAULT: 100

...

further arguments passed to polygon, like col, border, lwd

Author

Berry Boessenkool, , 2012

See Also

symbols, polygon

Examples

plot(1:20, type="n", asp=1)
circle(5,5, r=3)   # 1:1 aspect shows they're really circles and not ellipses.
circle(15,10, r=4, locnum=12, col=2, border=4, lwd=3)

# can not be vectorized:
x <- sample(1:20, 15) ;  y <- sample(1:20, 15) ; r <- runif(20)*3
circle(x,y,r, col=rgb(1,0.5,0,alpha=0.4), border=NA)
for(i in 1:15) circle(x[i],y[i],r[i], col=rgb(1,0.5,0,alpha=0.4), border=NA)