border {spatstat.geom}

Border Region of a Window

Description

Computes the border region of a window, that is, the region lying within a specified distance of the boundary of a window.

Usage

border(w, r, outside=FALSE, ...)

Arguments

w

A window (object of class "owin") or something acceptable to as.owin.

r

Numerical value.

outside

Logical value determining whether to compute the border outside or inside w.

...

Optional arguments passed to erosion (if outside=FALSE) or to dilation (if outside=TRUE).

Details

By default (if outside=FALSE), the border region is the subset of w lying within a distance r of the boundary of w. It is computed by eroding w by the distance r (using erosion) and subtracting this eroded window from the original window w.

If outside=TRUE, the border region is the set of locations outside w lying within a distance r of w. It is computed by dilating w by the distance r (using dilation) and subtracting the original window w from the dilated window.

Value

A window (object of class "owin").

Author(s)

Adrian Baddeley [e-mail]

and Rolf Turner [e-mail]

See Also

erosion, dilation

Examples

# rectangle
   u <- unit.square()
   border(u, 0.1)
   border(u, 0.1, outside=TRUE)
# polygon
   
   plot(letterR)
   plot(border(letterR, 0.1), add=TRUE)
   plot(border(letterR, 0.1, outside=TRUE), add=TRUE)