Build a PRIO-GRID neighbor table — pg_neighbor

Creates a reusable directed table of neighboring PRIO-GRID cells using queen or rook contiguity, a distance band, or k-nearest neighbors.

Usage

pg_neighbor_table(
  pgid = NULL,
  candidates = NULL,
  method = c("queen", "rook", "distance", "knn"),
  distance = NULL,
  k = 1L,
  include_self = FALSE,
  wrap_longitude = TRUE,
  config = priogrid::pg_current_config()
)

Arguments

pgid: Source cell IDs. NULL uses all configured cells.
candidates: Candidate neighbor cell IDs. NULL uses all configured cells.
method: Neighborhood definition: queen contiguity, rook contiguity, a distance band, or k-nearest neighbors.
distance: Maximum great-circle distance in kilometres. Required for method = "distance".
k: Number of neighbors for method = "knn".
include_self: Should a cell be allowed to neighbor itself?
wrap_longitude: Should contiguity wrap across the antimeridian?
config: A PRIO-GRID configuration object.

Value

A data frame with pgid and neighbor_pgid. Distance and k-nearest tables also contain distance_km.

Examples

config <- priogrid::pg_config(nrow = 18, ncol = 36)
pg_neighbor_table(20, method = "rook", config = config)
#>   pgid neighbor_pgid
#> 1   20            19
#> 2   20            21
#> 3   20            56
pg_neighbor_table(1:3, candidates = 1:6, method = "knn", k = 2,
                  config = config)
#>   pgid neighbor_pgid distance_km
#> 1    1             2    96.79089
#> 2    1             3   192.85065
#> 3    2             3    96.79089
#> 4    2             1    96.79089
#> 5    3             2    96.79089
#> 6    3             4    96.79089