terra (version 1.2-10)

adjacent: Adjacent cells

Description

Identify cells that are adjacent to a set of raster cells. Or identify adjacent polygons

Usage

# S4 method for SpatRaster
adjacent(x, cells, directions="rook", include=FALSE)
# S4 method for SpatVector
adjacent(x, type="rook", pairs=TRUE, symmetrical=FALSE	)

Arguments

x

SpatRaster

cells

vector of cell numbers for which adjacent cells should be found. Cell numbers start with 1 in the upper-left corner and increase from left to right and from top to bottom

directions

the directions in which cells should be connected: "rook" (4 directions), "queen" (8 directions), "16" (knight and one-cell queen moves), or "bishop" to connect cells with one-cell diagonal moves.

include

logical. Should the focal cells be included in the result?

type

character. One of "rook", "queen", "touches", or "intersects". "queen" and "touches" are synonyms. "rook" exclude polygons that touch at a single node only. "intersects" includes polygons that touch or overlap

pairs

logical. If TRUE a "from", "to" matrix is returned

symmetrical

logical. If TRUE, an adjacent pair is only included once. For example, if polygon 1 is adjacent to polygon 3, the implied adjacency between 3 and 1 is not reported

Value

matrix

See Also

relate, nearby

Examples

# NOT RUN {
r <- rast(nrows=10, ncols=10)
adjacent(r, cells=c(1, 5, 55), directions="queen") 
r <- rast(nrows=10, ncols=10, crs="+proj=utm +zone=1 +datum=WGS84")
adjacent(r, cells=11, directions="rook") 
# global lat/lon wraps around
r <- rast(nrows=10, ncols=10, crs="+proj=longlat +datum=WGS84")
adjacent(r, cells=11, directions="rook") 

f <- system.file("ex/lux.shp", package="terra")
v <- vect(f)
a <- adjacent(v, symmetrical=TRUE)
head(a)
# }