focalWeight: Focal weights matrix
In raster: Geographic Data Analysis and Modeling

focalWeight

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'), fillNA=FALSE)

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

Value

matrix that can be used in focal

Examples

r <- raster(ncols=180, nrows=180, xmn=0, crs="+proj=utm +zone=1")
# Gaussian filter for square cells
gf <- focalWeight(r, .5, "Gauss")
focalWeight(r, 2, "circle", fillNA=TRUE)

raster documentation built on Oct. 3, 2024, 1:08 a.m.