| as.im {spatstat} | R Documentation |
Converts various kinds of data to a pixel image
as.im(X, W, ...)
X |
Data to be converted to a pixel image. |
W |
Window object required when X is a function. |
... |
Additional arguments passed to X when X
is a function. |
This function converts the data x into a pixel image
object of class "im" (see im.object).
Currently X may be any of the following:
"im". This object is just returned.
"owin" (see owin.object).
This window is first converted to a binary image mask
by as.mask. Then the pixel entries
TRUE and FALSE are converted to
1 and NA respectively.
The result is returned as an object of class "im".
function(x, y, ...)
which is to be evaluated to yield the image pixel values.
In this case, the additional argument W must be
a window object. This window will be converted to
a binary image mask. Then the function X will be evaluated
in the form X(x, y, ...) where x and y are
vectors containing the x and y coordinates
of all the pixels in the image mask. This must return a numeric vector
of the same length as the input vectors, giving the pixel values.
win.
x, y, z in the format expected by
the standard R functions
contour.default and image.default.
That is, z is a matrix of pixel values, x and y
are vectors of x and y coordinates respectively,
and z[i,j] is the pixel value for the location
(x[i],y[j]).
An image object of class "im".
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
data(demopat)
# window object
W <- demopat$window
plot(W)
Z <- as.im(W)
image(Z)
# function
Z <- as.im(function(x,y) {x^2 + y^2}, unit.square())
image(Z)
# function with extra arguments
f <- function(x, y, x0, y0) {
sqrt((x - x0)^2 + (y-y0)^2)
}
Z <- as.im(f, unit.square(), x0=0.5, y0=0.5)
image(Z)
# Revisit the Sixties
data(letterR)
Z <- as.im(f, letterR, x0=2.5, y0=2)
image(Z)
# usual convention in S
stuff <- list(x=1:10, y=1:10, z=matrix(1:100, nrow=10))
Z <- as.im(stuff)