Intersection or Union of Two Windows

Description

Yields the intersection or union of two windows.

Usage

   intersect.owin(A, B, ...)
   union.owin(A,B, ...)

Arguments

Details

The function intersect.owin computes the intersection between the two windows A and B, while union.owin computes their union.

The arguments A and B must be window objects (either objects of class "owin", or data that can be coerced to this class by as.owin).

At present the intersection or union of two polygons is computed by discretising them, yielding a binary image mask.

If the intersection or union is empty, an error occurs.

Value

A window object.

Author(s)

Adrian Baddeley adrian@maths.uwa.edu.au http://www.maths.uwa.edu.au/~adrian/ and Rolf Turner rolf@math.unb.ca http://www.math.unb.ca/~rolf

See Also

is.subset.owin, overlap.owin, bounding.box, owin.object

Examples

# rectangles
   u <- unit.square()
   v <- owin(c(0.5,3.5), c(0.4,2.5))
# polygon
   data(letterR)
# mask
   m <- as.mask(letterR)

# two rectangles
   intersect.owin(u, v) 
   union.owin(u,v)

# polygon and rectangle
   intersect.owin(letterR, v)
   union.owin(letterR,v)

# mask and rectangle
   intersect.owin(m, v)
   union.owin(m,v)

# mask and polygon
   p <- rotate(v, 0.2)
   intersect.owin(m, p)
   union.owin(m,p)
#
   A <- letterR
   B <- rotate(letterR, 0.2)
   plot(bounding.box(A,B), main="intersection")
   w <- intersect.owin(A, B)
   plot(w, add=TRUE)
   plot(A, add=TRUE)
   plot(B, add=TRUE)

   plot(bounding.box(A,B), main="union")
   w <- union.owin(A,B)
   plot(w, add=TRUE)   
   plot(A, add=TRUE)
   plot(B, add=TRUE)