R: Focal weights matrix

focalMat {terra} | R Documentation

## Focal weights matrix

### Description

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

### Usage

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

### Arguments

`x` | SpatRaster
`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*sigma)
`type` | character indicating the type of filter to be returned

### Value

matrix that can be used with `focal`

### Examples

    r <- rast(ncol=180, nrow=180, xmin=0)
    focalMat(r, 2, "circle")

    focalMat(r, c(2,3), "rect")

    # Gaussian filter for square cells
    gf <- focalMat(r, 1, "Gauss")

[Package terra version 1.2-5 Index]