R: Focal weights matrix

focalWeight {raster} | R Documentation

## Focal weights matrix

### Description

Calculate focal ("moving window") weight matrix for use in the `focal` function. The sum of the values adds up to one.

### Usage

    focalWeight(x, d, type=c('circle', 'Gauss', 'rectangle'))

### Arguments

`x` | Raster* object
`d` | numeric. If `type=circle`, the radius of the circle (in units of the CRS). If `type=rectangle` the dimension of the rectangle (one or two numbers). If `type=Gauss` the size of sigma, and optionally another number to determine the size of the matrix returned (default is 3 times sigma)
`type` | character indicating the type of filter to be returned

### Value

matrix that can be used in `focal`

### Examples

    r <- raster(ncols=36, nrows=18, xmn=0)
    # Gaussian filter for square cells
    gf <- focalWeight(r, 2, "Gauss")

[Package raster version 2.5-8 Index]