raster.x: Cartesian Coordinates for a Pixel Raster

Description

Return the $x$ and $y$ coordinates of each pixel in a binary pixel image.

Usage

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

Arguments

A window (an object of class "owin") of type "mask" representing a binary pixel image.

Value

raster.x and raster.y return 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.
raster.xy returns a list with components x and y which are numeric vectors of equal length containing the pixel coordinates.

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. The functions raster.x and raster.y return 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.

The function raster.xy returns a list with components x and y which are numeric vectors of equal length containing the pixel coordinates.

Examples

Run this code

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))
  plot(disc)
  # approximation to the unit disc