# fasp.object

##### Function Arrays for Spatial Patterns

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 \(1 \le i,j \le n\). 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.
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.

##### See Also

##### Examples

```
# NOT RUN {
# multitype point pattern
data(amacrine)
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)
# }
```

*Documentation reproduced from package spatstat, version 1.57-1, License: GPL (>= 2)*