getellipse {shape}R Documentation

x-y coordinates of ellipse

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.

Details

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

Value

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

Author(s)

Karline Soetaert <k.soetaert@nioo.knaw.nl>

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)
  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)

[Package shape version 1.2.2 Index]