A simple class of functions of spatial location
funxy(f, W)A function in the R language
with arguments x,y (at least)
Window (object of class "owin") inside which the
function is well-defined.
A function with the same arguments as f,
which also belongs to the class "funxy".
This class has methods for
print, plot, contour and persp.
This creates an object of class "funxy".
This is a simple mechanism for handling a function
of spatial location
f should be a function in the R language.
The first two arguments of f must be named x and y
respectively.
W should be a window (object of class "owin") inside which the
function f is well-defined.
The function f should be vectorised: that is,
if x and y are numeric vectors of the same length
n, then v <- f(x,y) should be a vector of length
n.
The resulting function g <- funxy(f, W) has the same formal
arguments as f. It accepts numeric vectors x,y as
described above, but if y is missing, then x may be
a point pattern (object of class "ppp" or "lpp") from
which the coordinates should be extracted.
# NOT RUN {
f <- function(x,y) { x^2 + y^2 - 1}
g <- funxy(f, square(2))
g(0.2, 0.3)
g
g(cells[1:4])
# }
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