R: Divide Image Into Sub-images

split.im {spatstat} | R Documentation

## Divide Image Into Sub-images

### Description

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.

If `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 `"solist"` so that it can be plotted immediately.

If `drop=TRUE`, a list of numeric vectors.

### Author(s)

Adrian Baddeley Adrian.Baddeley@curtin.edu.au

and Rolf Turner r.turner@auckland.ac.nz

### See Also

`by.im`, `tess`, `im`

### 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))

[Package spatstat version 1.54-0 Index]