focalMat function

Focal weights matrix

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

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

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
• fillNA: logical. If TRUE, zeros are set to NA such that they are ignored in the computations. Only applies to type="circle"

Returns

matrix that can be used with focal

Examples

r <- rast(ncols=180, nrows=180, xmin=0)
focalMat(r, 2, "circle")

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

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