terra: patches – R documentation

Become an expert in R — Interactive courses, Cheat Sheets, certificates and more!

patches

Detect patches (clumps) of cells

Description

Detect patches (clumps). Patches are groups of cells that are surrounded by cells that are NA. Set zeroAsNA to TRUE to also identify patches separated by cells with values of zero.

Usage

## S4 method for signature 'SpatRaster'
patches(x, directions=4, zeroAsNA=FALSE, filename="", ...)

Arguments

`x`	SpatRaster
`directions`	integer indicating which cells are considered adjacent. Should be 8 (Queen's case) or 4 (Rook's case)
`zeroAsNA`	logical. If `TRUE` treat cells that are zero as if they were `NA`
`filename`	character. Output filename
`...`	options for writing files as in `writeRaster`

Value

SpatRaster. Cell values are either a patch number

Examples

r <- rast(nrow=18, ncol=36, xmin=0)
r[1:2, 5:8] <- 1
r[5:8, 2:6] <- 1
r[7:12, 22:36] <- 1
r[15:16, 18:29] <- 1
p <- patches(r)

r <- rast(nrow=10, ncol=10, xmin=0)
r[] <- 0
r[3, 3] <- 10
r[4, 4] <- 10
r[5, 5:8] <- 12
r[6, 6:9] <- 12

# remove zeros if need be with zeroAsNA

p4 <- patches(r, zeroAsNA=TRUE)
p8 <- patches(r, 8, zeroAsNA=TRUE)

# patches for different values
# remove zeros
rr <- classify(r, cbind(0, NA))
# first make layers for each value
s <- segregate(rr, keep=TRUE, other=NA)
p <- patches(s)

terra

Spatial Data Analysis

v1.2-10

GPL (>= 3)

Authors

Robert J. Hijmans [cre, aut] (<https://orcid.org/0000-0001-5872-2872>), Roger Bivand [ctb] (<https://orcid.org/0000-0003-2392-6140>), Karl Forner [ctb], Jeroen Ooms [ctb] (<https://orcid.org/0000-0002-4035-0289>), Edzer Pebesma [ctb] (<https://orcid.org/0000-0001-8049-7069>)

Initial release

2021-05-12