Cartesian Coordinates for a Pixel Raster

Description

Returns a matrix giving the x (or y) coordinates of each pixel in a binary pixel image.

Usage

 raster.x(w)
 raster.y(w)

Arguments

Details

The argument w should be a window (an object of class "owin", see owin.object for details). A window of type "mask" represents a binary pixel image. This function returns a matrix of the same dimensions as the binary pixel image itself, with entries giving the x coordinate (for raster.x) or y coordinate (for raster.y) of each pixel in the image.

Value

A matrix of the same dimensions as the pixel grid in w, and giving the value of the x (or y) coordinate of each pixel in the raster.

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

owin, as.mask

Examples

  u <- owin(c(-1,1),c(-1,1)) # square of side 2
  w <- as.mask(u, eps=0.01) # 200 x 200 grid
  X <- raster.x(w)
  Y <- raster.y(w)
  disc <- owin(c(-1,1), c(-1,1), mask=(X^2 + Y^2 <= 1))
  ## Not run: plot(disc)
  # approximation to the unit disc