# split.im

From spatstat v1.31-3
by Adrian Baddeley

##### Divide Image Into Sub-images

Divides a pixel image into several sub-images according to the value of a factor, or according to the tiles of a tessellation.

##### Usage

```
## S3 method for class 'im':
split(x, f, ..., drop = FALSE)
```

##### Arguments

- x
- Pixel image (object of class
`"im"`

). - f
- Splitting criterion. Either a tessellation (object of class
`"tess"`

) or a pixel image with factor values. - ...
- Ignored.
- drop
- Logical value determining whether each subset should
be returned as a pixel images (
`drop=FALSE`

) or as a one-dimensional vector of pixel values (`drop=TRUE`

).

##### Details

This is a method for the generic function `split`

for the class of pixel images. The image `x`

will be divided
into subsets determined by the data `f`

. The result is a list
of these subsets.

The splitting criterion may be either

- a tessellation (object of class
`"tess"`

). Each tile of the tessellation delineates a subset of the spatial domain. - a pixel image (object of class
`"im"`

) with factor values. The levels of the factor determine subsets of the spatial domain.

`drop=FALSE`

(the default), the result is a list of pixel
images, each one a subset of the pixel image `x`

,
obtained by restricting the pixel domain to one of the subsets.
If `drop=TRUE`

, then the pixel values are returned as
numeric vectors.
##### Value

- If
`drop=FALSE`

, a list of pixel images (objects of class`"im"`

). It is also of class`"listof"`

so that it can be plotted immediately.If

`drop=TRUE`

, a list of numeric vectors.

##### See Also

##### Examples

```
W <- square(1)
X <- as.im(function(x,y){sqrt(x^2+y^2)}, W)
Y <- dirichlet(runifpoint(12, W))
plot(split(X,Y))
```

*Documentation reproduced from package spatstat, version 1.31-3, License: GPL (>= 2)*

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