sieve {terra}

R Documentation

Sieve filter

Description

Apply a sieve filter. That is, remove "noise", by changing small clumps of cells with a value that is different from the surrounding cells, to the value of the largest neighbouring clump.

Usage

## S4 method for signature 'SpatRaster'
sieve(x, threshold, directions=8, filename="", ...) 

Arguments

x	SpatRaster, single layer with elevation values. Values should have the same unit as the map units
threshold	positive integer. Only clumps smaller than this threshold will be removed
directions	numeric to indicate which cells are connected. Either 4 to only consider the horizontal and vertical neighbors ("rook"), or 8 to consider the vertical, horizontal and diagonal neighbors
filename	character. Output filename
...	Options for writing files as in writeRaster

See Also

focal

Examples

r <- rast(nrows=18, ncols=18, xmin=0, vals=0, crs="local")
r[2, 5] <- 1
r[5:8, 2:3] <- 2
r[7:12, 10:15] <- 3
r[15:16, 15:18] <- 4
freq(r, bylayer=FALSE)

x <- sieve(r, 8)
y <- sieve(r, 9)

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