# Extract.fasp

From spatstat v1.18-1
by Adrian Baddeley

##### Extract Subset of Function Array

Extract a subset of a function array (an object of class
`"fasp"`

).

##### Usage

```
## S3 method for class 'fasp':
[(x, I, J, drop=TRUE,\dots)
```

##### Arguments

- x
- A function array. An object of class
`"fasp"`

. - I
- any valid expression for a subset of the row indices of the array.
- J
- any valid expression for a subset of the column indices of the array.
- drop
- Logical.
When the selected subset consists of only one cell of the array,
if
`drop=FALSE`

the result is still returned as a $1 \times 1$ array of functions (class`"fasp"`

) while if`drop=TRUE`

it i - ...
- Ignored.

##### Details

A function array can be regarded as a matrix whose entries
are functions. See `fasp.object`

for an explanation of
function arrays.

This routine extracts a sub-array according to the usual conventions for matrix indexing.

##### Value

- A function array (of class
`"fasp"`

). Exceptionally, if the array has only one cell, and if`drop=TRUE`

, then the result is a function value table (class`"fv"`

).

##### See Also

##### Examples

```
# Lansing woods data - multitype points with 6 types
data(lansing)
<testonly># smaller dataset
lansing <- lansing[ seq(1,lansing$n,by=45), ]</testonly>
# compute 6 x 6 array of all cross-type K functions
a <- alltypes(lansing, "K")
# extract first three marks only
b <- a[1:3,1:3]
plot(b)
# subset pertaining to hickories
h <- a[levels(lansing$marks) == "hickory", ]
plot(h)
```

*Documentation reproduced from package spatstat, version 1.18-1, License: GPL (>= 2)*

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