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 # }