# fasp.object

##### Function Arrays for Spatial Patterns

A class `"fasp"`

to represent a

##### 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:

[object Object],[object Object],[object Object],[object Object],[object Object]

##### 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

```
# 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 1.18-2, License: GPL (>= 2)*