bdist.pixels

0th

Percentile

Distance to Boundary of Window

Computes the distances from each pixel in a window to the boundary of the window.

Keywords
spatial, math
Usage
bdist.pixels(w, ..., coords=TRUE)
Arguments
w
A window (object of class "owin").
...
Arguments passed to as.mask to determine the pixel resolution.
coords
Logical: if TRUE, the result can be displayed using persp, contour etc.
Details

This function computes, for each pixel $u$ in the window w, the shortest distance $d(u, W^c)$ from $u$ to the boundary of $W$.

If the window is not of type "mask" then it is first converted to that type. The arguments "..." are passed to as.mask to determine the pixel resolution.

Value

  • If coords is false, a matrix giving the distances from each pixel in the image raster to the boundary of the window. Rows of this matrix correspond to the $y$ coordinate and columns to the $x$ coordinate. If coords is true, a list with three components x,y,z, where x,y are vectors of length $m,n$ giving the $x$ and $y$ coordinates respectively, and z is an $m \times n$ matrix such that z[i,j] is the distance from (x[i],y[j]) to the boundary of the window. Rows of this matrix correspond to the $x$ coordinate and columns to the $y$ coordinate. This result can be plotted with persp, image or contour.

See Also

owin.object, erode.owin, bdist.points,

Aliases
  • bdist.pixels
Examples
u <- owin(c(0,1),c(0,1))
  d <- bdist.pixels(u, eps=0.01)
  image(d)
  d <- bdist.pixels(u, eps=0.01, coords=FALSE)
  mean(d >= 0.1)
  # value is approx (1 - 2 * 0.1)^2 = 0.64
Documentation reproduced from package spatstat, version 1.11-2, License: GPL version 2 or newer

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