Return the \(x\) and \(y\) coordinates of each pixel in a pixel image or binary mask.
raster.x(w, drop=FALSE)
raster.y(w, drop=FALSE)
raster.xy(w, drop=FALSE)A pixel image (object of class "im") or a
mask window (object of class "owin"
of type "mask").
Logical.
If TRUE, then coordinates of pixels that lie outside the
window are removed.
If FALSE (the default) then the coordinates of every
pixel in the containing rectangle are retained.
raster.xy returns a list with components x and y
which are numeric vectors of equal length containing the pixel coordinates.
If drop=FALSE,
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.
If drop=TRUE,
raster.x and raster.y return numeric vectors.
The argument w should be either
a pixel image (object of class "im")
or a mask window (an object of class
"owin" of type "mask").
If drop=FALSE (the default), the
functions raster.x and raster.y return
a matrix of the same dimensions as the
pixel image or mask itself, with entries giving the \(x\) coordinate
(for raster.x) or \(y\) coordinate (for raster.y)
of each pixel in the pixel grid.
If drop=TRUE, pixels that lie outside the
window w (or outside the domain of the image w)
are removed, and raster.x and raster.y
return numeric vectors containing the coordinates of the
pixels that are inside the window w.
The function raster.xy returns a list
with components x and y
which are numeric vectors of equal length containing the pixel coordinates.
# NOT RUN {
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
# }