getellipse: x-y coordinates of ellipse

In shape: Functions for Plotting Graphical Shapes, Colors

Description

calculates x-y values for (part of) an ellipse; the ellipse can be rotated

Usage

getellipse(rx = 1, ry = rx, mid = c(0, 0), dr = 0.01, 
           angle = 0, from = -pi, to = pi)

Arguments

rx	long radius of ellipse.
ry	short radius of ellipse.
mid	midpoint of ellipse.
dr	size of segments, in radians, to specify ellipse (decrease for smoother).
angle	rotation angle, degrees.
from	starting angle for ellipse segment, radians.
to	final angle for ellipse segment, radians. The segment is generated counterclockwise. The default is draw a full ellipse.

Details

rx and ry are the horizontal and vertical radiusses of the ellipses.

points from and to are joined counterclockwise. (this has changed since version 1.3.4).

Value

a 2-column matrix with x-y values of the ellipse

Author(s)

Karline Soetaert <[e-mail]>

See Also

plotellipse, filledellipse

Examples

plot(getellipse(1, from = 0, to = pi/2), type = "l", col = "red",
     lwd = 2, main = "getellipse")
lines(getellipse(0.5, 0.25, mid = c(0.5, 0.5)), type = "l", 
      col = "blue", lwd = 2)
lines(getellipse(0.5, 0.25, mid = c(0.5, 0.5), angle = 45), 
      type = "l", col = "green", lwd = 2)

lines(getellipse(0.2, 0.2, mid = c(0.5, 0.5), from = 0, to = pi/2), 
      type = "l", col = "orange", lwd = 2)
lines(getellipse(0.2, 0.2, mid = c(0.5, 0.5), from = pi/2, to = 0), 
      type = "l", col = "black", lwd = 2)
lines(getellipse(0.1, 0.1, mid = c(0.75, 0.5), from = -pi/2, to = pi/2), 
      type = "l", col = "black", lwd = 2)

emptyplot(main = "getellipse")
col <- femmecol(90)
for (i in seq(0, 180, by = 2)) 
      lines(getellipse(0.5, 0.25, mid = c(0.5, 0.5), angle = i),
            type = "l", col = col[(i/2)+1], lwd = 2)

Example output

shape documentation built on May 4, 2021, 3 p.m.