# funxy

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##### Spatial Function Class

A simple class of functions of spatial location

Keywords
spatial, math
##### Usage
funxy(f, W)
##### Arguments
f

A function in the R language with arguments x,y (at least)

W

Window (object of class "owin") inside which the function is well-defined.

##### Details

This creates an object of class "funxy". This is a simple mechanism for handling a function of spatial location $f(x,y)$ to make it easier to display and manipulate.

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 and can be called in the same way, v <- g(x,y) where x and y are numeric vectors. However it can also be called as v <- g(X), where X is a point pattern (object of class "ppp" or "lpp") or a quadrature scheme (class "quad"); the function will be evaluated at the points of X.

##### Value

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.

plot.funxy, summary.funxy

• funxy
##### Examples
# NOT RUN {
f <- function(x,y) { x^2 + y^2 - 1}
g <- funxy(f, square(2))
g
## evaluate function at any x, y coordinates
g(0.2, 0.3)
## evaluate function at the points of a point pattern
g(cells[1:4])
# }

Documentation reproduced from package spatstat, version 1.63-0, License: GPL (>= 2)

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