Function Arrays for Spatial Patterns

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


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 $1 \le i,j \le n$. 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 $1 \times m$ array of functions. Alternatively we may compute a summary function for each possible pair of types $(i,j)$. This produces an $m \times m$ 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. For univariate (single-type) point patterns the command allstats will compute an array of different summary functions $F$, $G$, $J$, $K$ for the same dataset. Both alltypes and allstats return an object of class "fasp".

There are methods for plot and "[" in this class. The plot method displays the entire array of functions. The method "[.fasp" selects a sub-array using the natural indices i,j.

An object of class "fasp" is a list containing at least the following components: fns{ A list, each component fns[[i]] of which represents a function. The precise format of fns[[i]] depends on the function which it represents, but it is a list containing several labelled components. } 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. }

See Also

alltypes, allstats, plot.fasp, "[.fasp"

  • fasp.object
# unmarked point pattern
        a <- allstats(swedishpines,dataname="Swedish Pines")
        plot(a, subset=list("r<=15","r<=15","r<=15","r<=50"))

        # multitype point pattern
        a <- alltypes(lansing, "G")
        plot(a["blackoak", ])
Documentation reproduced from package spatstat, version 1.0-1, License: GPL version 2 or newer

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