Elliptical Window.
Create an elliptical window.
ellipse(a, b, centre=c(0,0), phi=0, ..., mask=FALSE, npoly = 128)
a,b |
The half-lengths of the axes of the ellipse. |
centre |
The centre of the ellipse. |
phi |
The (anti-clockwise) angle through which the ellipse should be
rotated (about its centre) starting from an orientation in which
the axis of half-length |
mask |
Logical value controlling the type of approximation to a perfect ellipse. See Details. |
... |
Arguments passed to |
npoly |
The number of edges in the polygonal approximation to the ellipse. |
This command creates a window object representing an ellipse with the given centre and axes.
By default, the ellipse is
approximated by a polygon with npoly edges.
If mask=TRUE, then the ellipse is approximated by a binary pixel
mask. The resolution of the mask is controlled by
the arguments ... which are passed to as.mask.
The arguments a and b must be single positive numbers.
The argument centre specifies the ellipse centre: it can be either
a numeric vector of length 2 giving the coordinates,
or a list(x,y) giving the coordinates of exactly one point, or a
point pattern (object of class "ppp") containing exactly one point.
An object of class owin (either of type “polygonal”
or of type “mask”) specifying an elliptical window.
Adrian Baddeley Adrian.Baddeley@curtin.edu.au
and Rolf Turner r.turner@auckland.ac.nz
W <- ellipse(a=5,b=2,centre=c(5,1),phi=pi/6) plot(W,lwd=2,border="red") WM <- ellipse(a=5,b=2,centre=c(5,1),phi=pi/6,mask=TRUE,dimyx=512) plot(WM,add=TRUE,box=FALSE)
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