Draw a Circle

Draw one or several circle on an existing plot. 

DrawCircle(x = 0, y = x, r.out = 1, r.in = 0,
           theta.1 = 0, theta.2 = 2*pi, border = par("fg"),
           col = NA, lty = par("lty"), lwd = par("lwd"),
           nv = 100, plot = TRUE)

Arguments

x, y

a vector (or scalar) of xy-coordinates for the center(s) of the circle(s).

r.out

a vector (or scalar) of the outer radius of the circle.

r.in

a vector (or scalar) of a potential inner radius of an annulus.

theta.1

a vector (or scalar) of the starting angle(s). The sectors are built counterclockwise.

theta.2

a vector (or scalar) of the ending angle(s).

nv

number of vertices to draw the circle.

border

color for circle borders. The default is par("fg"). Use border = NA to omit borders.

col

color(s) to fill or shade the circle(s) with. The default NA (or also NULL) means do not fill, i.e., draw transparent circles, unless density is specified.

lty

line type for borders and shading; defaults to "solid".

lwd

line width for borders and shading.

plot

logical. If TRUE the structure will be plotted. If FALSE only the points are calculated and returned. Use this option if you want to combine several geometric structures to a polygon.

Details

All geometric arguments will be recycled.

Value

The function invisibly returns a list of the calculated coordinates for all shapes.

Author

Andri Signorell <andri@signorell.net>

Examples

Canvas(xlim = c(-5,5), xpd=TRUE)
cols <- Pal("Helsana")[1:4]

# Draw ring
DrawCircle (r.in = 1, r.out = 5, border="darkgrey", 
            col=SetAlpha(DescTools::hyellow, 0.2), lwd=2)

# Draw circle
DrawCircle (r.in = 6, border=DescTools::hgreen, lwd=3)

# Draw sectors
geom <- rbind(c(-pi, 0, .25, .5), c(0, pi, 1, 2),
              c(-pi/2, pi/2, 2, 2.5), c(pi/2, 3 * pi/2, 3, 4),
              c(pi - pi/8, pi + pi/8, 1.5, 2.5))

DrawCircle (r.in = geom[,3], r.out = geom[,4],
           theta.1 = geom[,1], theta.2 = geom[,2],
           col = SetAlpha(cols, 0.6),
           border = cols, lwd=1)



# clipping
Canvas(bg="lightgrey", main="Yin ~ Yang")
DrawCircle (r.out = 1, col="white")
clip(0, 2, 2, -2)
DrawCircle(col="black")
clip(-2, 2, 2, -2)
DrawCircle (y = c(-0.5,0.5), r.out = 0.5, col=c("black", "white"), border=NA)
DrawCircle (y = c(-0.5,0.5), r.out = 0.1, col=c("white", "black"), border=NA)
DrawCircle ()



# overplotting circles
Canvas(xlim=c(-5,5))
DrawCircle (r.out=4:1, col=c("white", "steelblue2", "white", "red"), lwd=3, nv=300)



# rotation
x <- seq(-3, 3, length.out=10)
y <- rep(0, length.out=length(x))

Canvas(xlim=c(-5,5), bg="black")

sapply( (0:11) * pi/6, function(theta) {
  xy <- Rotate(x, y=y, theta=theta)
  DrawCircle (x=xy$x, y=xy$y, r.in=2.4, border=SetAlpha("white", 0.2))
} )

#>       [,1]   [,2]   [,3]   [,4]   [,5]   [,6]   [,7]   [,8]   [,9]   [,10] 
#>  [1,] list,2 list,2 list,2 list,2 list,2 list,2 list,2 list,2 list,2 list,2
#>  [2,] list,2 list,2 list,2 list,2 list,2 list,2 list,2 list,2 list,2 list,2
#>  [3,] list,2 list,2 list,2 list,2 list,2 list,2 list,2 list,2 list,2 list,2
#>  [4,] list,2 list,2 list,2 list,2 list,2 list,2 list,2 list,2 list,2 list,2
#>  [5,] list,2 list,2 list,2 list,2 list,2 list,2 list,2 list,2 list,2 list,2
#>  [6,] list,2 list,2 list,2 list,2 list,2 list,2 list,2 list,2 list,2 list,2
#>  [7,] list,2 list,2 list,2 list,2 list,2 list,2 list,2 list,2 list,2 list,2
#>  [8,] list,2 list,2 list,2 list,2 list,2 list,2 list,2 list,2 list,2 list,2
#>  [9,] list,2 list,2 list,2 list,2 list,2 list,2 list,2 list,2 list,2 list,2
#> [10,] list,2 list,2 list,2 list,2 list,2 list,2 list,2 list,2 list,2 list,2
#>       [,11]  [,12] 
#>  [1,] list,2 list,2
#>  [2,] list,2 list,2
#>  [3,] list,2 list,2
#>  [4,] list,2 list,2
#>  [5,] list,2 list,2
#>  [6,] list,2 list,2
#>  [7,] list,2 list,2
#>  [8,] list,2 list,2
#>  [9,] list,2 list,2
#> [10,] list,2 list,2