spatstat (version 1.18-4)

intersect.owin: Intersection, Union or Set Subtraction of Two Windows

Description

Yields the intersection, union or set subtraction of two windows.

Usage

intersect.owin(A, B, ..., fatal=TRUE)
   union.owin(A,B, ...)
   setminus.owin(A,B, ...)

Arguments

A

A window object (see Details).

B

A window object.

...

Optional arguments passed to as.mask to control the discretisation, if required.

fatal

Logical. Determines what happens if the intersection is empty.

Value

• A window (object of class "owin").

Details

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

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).

If the intersection is empty, then if fatal=FALSE the result is NULL, while if fatal=TRUE an error occurs.

The intersection or union of more than two windows can also be computed. For intersect.owin and union.owin the arguments ... can include additional window objects.

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)
   setminus.owin(u,v)

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

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

# mask and polygon
   p <- rotate(v, 0.2)
   intersect.owin(m, p)
   union.owin(m,p)
   setminus.owin(m,p)

# two polygons
   A <- letterR
   B <- rotate(letterR, 0.2)
   plot(bounding.box(A,B), main="intersection")
   w <- intersect.owin(A, B)
   plot(w, add=TRUE, col="lightblue")
   plot(A, add=TRUE)
   plot(B, add=TRUE)

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

   plot(bounding.box(A,B), main="set minus")
   w <- setminus.owin(A,B)
   plot(w, add=TRUE, col="lightblue")   
   plot(A, add=TRUE)
   plot(B, add=TRUE)

# intersection and union of three windows
   C <- shift(B, c(0.2, 0.3))
   plot(union.owin(A,B,C))
   plot(intersect.owin(A,B,C))