R: Spatial Function Class

funxy {spatstat.geom} | R Documentation

## Spatial Function Class

### Description

A simple class of functions of spatial location

### 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`.

### Author(s)

Adrian Baddeley Adrian.Baddeley@curtin.edu.au, Rolf Turner r.turner@auckland.ac.nz and Ege Rubak rubak@math.aau.dk.

### See Also

`plot.funxy`, `summary.funxy`

### Examples

       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])

[Package spatstat.geom version 2.2-0 Index]