Identify pairs of cells that are adjacent.
adjacencyFromTransition(x)TransitionLayer
A two column matrix with each row containing a pair of adjacent cells.
Extracts the indices of those cells that are connected (e.g. cells i,j that have a non-zero value in the transition matrix).
Cell numbers are unique indices of cells in the original grid. By convention, cell numbers start with 1 in the upper-left corner of the grid and increase from left to right and from top to bottom.
library("raster")
r <- raster(nrows = 6, ncols = 7,
xmn = 0, xmx = 7,
ymn = 0, ymx = 6,
crs = "+proj=utm +units=m")
r[] <- runif(6 * 7)
tr <- transition(r, function(x) 1 / mean(x), 8)
aft <- adjacencyFromTransition(tr)
head(aft)
#> [,1] [,2]
#> [1,] 2 1
#> [2,] 8 1
#> [3,] 9 1
#> [4,] 1 2
#> [5,] 3 2
#> [6,] 8 2