R: Function Arrays for Spatial Patterns

fasp.object {spatstat.core} | R Documentation

## Function Arrays for Spatial Patterns

### Description

A class `"fasp"` to represent a “matrix” of functions, amenable to plotting as a matrix of plot panels.

### Details

An object of this class is a convenient way of storing (and later plotting, editing, etc) a set of functions f[i,j](r) of a real argument r, defined for each possible pair (i,j) of indices 1 <= i,j <= n. We may think of this as a matrix or array of functions f[i,j].

Function arrays are particularly useful in the analysis of a multitype point pattern (a point pattern in which the points are identified as belonging to separate types). We may want to compute a summary function for the points of type i only, for each of the possible types i. This produces a 1 * m array of functions. Alternatively we may compute a summary function for each possible pair of types (i,j). This produces an m * m array of functions.

For multitype point patterns the command `alltypes` will compute arrays of summary functions for each possible type or for each possible pair of types. The function `alltypes` returns an object of class `"fasp"`.

An object of class `"fasp"` is a list containing at least the following components:

fns

  A list of data frames, each representing one of the functions.

which

  A matrix representing the spatial arrangement of the functions. If `which[i,j] = k` then the function represented by `fns[[k]]` should be plotted in the panel at position (i,j). If `which[i,j] = NA` then nothing is plotted in that position.

titles

  A list of character strings, providing suitable plotting titles for the functions.

default.formulae

  A list of default formulae for plotting each of the functions.

title

  A character string, giving a default title for the array when it is plotted.

### Functions available

There are methods for `plot`, `print` and `"["` for this class.

The plot method displays the entire array of functions. The method `[.fasp` selects a sub-array using the natural indices `i,j`.

The command `eval.fasp` can be used to apply a transformation to each function in the array, and to combine two arrays.

### Author(s)

Adrian Baddeley Adrian.Baddeley@curtin.edu.au

and Rolf Turner r.turner@auckland.ac.nz

### See Also

`alltypes`, `plot.fasp`, `[.fasp`, `eval.fasp`

### Examples

      GG <- alltypes(amacrine, 'G')

      plot(GG)

      # select the row corresponding to cells of type "on"
      Gon <- GG["on", ]
      plot(Gon)

      # extract the G function for i = "on", j = "off"
      Gonoff <- GG["on", "off", drop=TRUE]

      # Fisher variance stabilising transformation
      GGfish <- eval.fasp(asin(sqrt(GG)))
      plot(GGfish)

[Package spatstat.core version 2.0-0 Index]