border: 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

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

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).

Value

A window (object of class "owin").

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.

Examples

Run this code

# rectangle
   u <- unit.square()
   border(u, 0.1)
   border(u, 0.1, outside=TRUE)
# polygon
   <testonly>opa <- spatstat.options(npixel=32)</testonly>
   data(letterR)
   plot(letterR)
   plot(border(letterR, 0.1), add=TRUE)
   plot(border(letterR, 0.1, outside=TRUE), add=TRUE)
   <testonly>spatstat.options(opa)</testonly>