Get all indices in neighbourhood

Source: R/index.R

Get all indices in neighbourhood

neighbour_idx(mat, idx, mask = NULL, diagonal = TRUE,
  include.idx = FALSE)

Arguments

mat

matrix or data.frame
idx

two-element vector
mask

logical matrix; optional
diagonal

include diagonal neighbours
include.idx

include current index

Examples

mat <- matrix(0, 3, 3)
neighbour_idx(mat, c(1, 2))
#> [[1]]
#> [1] 1 1
#> 
#> [[2]]
#> [1] 1 3
#> 
#> [[3]]
#> [1] 2 1
#> 
#> [[4]]
#> [1] 2 2
#> 
#> [[5]]
#> [1] 2 3
#> 
neighbour_idx(mat, c(1, 2), diagonal = FALSE)
#> [[1]]
#> [1] 1 1
#> 
#> [[2]]
#> [1] 1 3
#> 
#> [[3]]
#> [1] 2 2
#> 
neighbour_idx(mat, c(1, 2), diagonal = FALSE, include.idx = TRUE)
#> [[1]]
#> [1] 1 1
#> 
#> [[2]]
#> [1] 1 2
#> 
#> [[3]]
#> [1] 1 3
#> 
#> [[4]]
#> [1] 2 2
#> 
# With mask
mat <- matrix(0, 3, 4)
mask <- m(FALSE, FALSE, TRUE, TRUE |
          FALSE, FALSE, FALSE, FALSE |
          TRUE, TRUE, FALSE, TRUE)
neighbour_idx(mat, c(1, 2), mask = mask)
#> [[1]]
#> [1] 1 3
#>