R: Extract or Change the Window of a Spatial Object

Window {spatstat} | R Documentation

## Extract or Change the Window of a Spatial Object

### Description

Given a spatial object (such as a point pattern or pixel image) in two dimensions, these functions extract or change the window in which the object is defined.

### Usage

       Window(X, ...)

       Window(X, ...) <- value

       ## S3 method for class 'ppp'
    Window(X, ...)

       ## S3 replacement method for class 'ppp'
    Window(X, ...) <- value

       ## S3 method for class 'psp'
    Window(X, ...)

       ## S3 replacement method for class 'psp'
    Window(X, ...) <- value

       ## S3 method for class 'im'
    Window(X, ...)

       ## S3 replacement method for class 'im'
    Window(X, ...) <- value

### Arguments

`X` | A spatial object such as a point pattern, line segment pattern or pixel image.
`...` | Extra arguments. They are ignored by all the methods listed here.
`value` | Another window (object of class `"owin"`) to be used as the window for `X`.

### Details

The functions `Window` and `Window<-` are generic.

`Window(X)` extracts the spatial window in which `X` is defined.

`Window(X) <- W` changes the window in which `X` is defined to the new window `W`, and discards any data outside `W`. In particular:

- If `X` is a point pattern (object of class `"ppp"`) then `Window(X) <- W` discards any points of `X` which fall outside `W`.

- If `X` is a line segment pattern (object of class `"psp"`) then `Window(X) <- W` clips the segments of `X` to the boundaries of `W`.

- If `X` is a pixel image (object of class `"im"`) then `Window(X) <- W` has the effect that pixels lying outside `W` are retained but their pixel values are set to `NA`.

Many other classes of spatial object have a method for `Window`, but not `Window<-`. See `Window.ppm`.

### Value

The result of `Window` is a window (object of class `"owin"`).

The result of `Window<-` is the updated object `X`, of the same class as `X`.

### Author(s)

Adrian Baddeley Adrian.Baddeley@curtin.edu.au

Rolf Turner r.turner@auckland.ac.nz

and Ege Rubak rubak@math.aau.dk

### See Also

`Window.ppm`

### Examples

       ## point patterns
       Window(cells)
       X <- demopat
       Window(X)
       Window(X) <- as.rectangle(Window(X))

       ## line segment patterns
       X <- psp(runif(10), runif(10), runif(10), runif(10), window=owin())
       Window(X)
       Window(X) <- square(0.5)

       ## images
       Z <- setcov(owin())
       Window(Z)
       Window(Z) <- square(0.5)

[Package spatstat version 1.54-0 Index]