Construct a spatial weights matrix

A thin, opinionated wrapper around common spdep weights constructors. Returns a standardized slx_W object that carries both the sparse matrix and the listw form used by downstream routines.

Usage

slx_weights(
  x = NULL,
  style = c("contiguity", "rook", "knn", "distance", "custom"),
  k = 5,
  threshold = NULL,
  row_standardize = TRUE,
  matrix = NULL,
  ...
)

Arguments

x

An sf object (for "contiguity", "knn", "distance"), a matrix of coordinates, or a raw numeric/sparse matrix (for "custom").

style

Weights style. One of "contiguity" (queen), "rook", "knn", "distance", or "custom".

k

Number of neighbors for style = "knn".

threshold

Distance threshold for style = "distance" (units of the coordinate system).

row_standardize

Logical; row-standardize the matrix? Default TRUE. The paper notes row-standardization is a theoretical choice; set to FALSE when connection count should itself carry weight.

matrix

A numeric or sparse Matrix for style = "custom".

...

Passed to the underlying spdep constructor.

Value

An object of class slx_W with elements W (sparse matrix), listw (spdep listw object), style, and row_standardized.

Examples

# Custom weights matrix from bundled data
data(defense_burden)
W <- slx_weights(style = "custom", matrix = defense_burden$W_contig,
                 row_standardize = FALSE)
W
#> <slx_W>  n = 179   style = custom   row-standardized = FALSE 

# \donttest{
# Contiguity weights from an sf polygon layer
if (requireNamespace("sf", quietly = TRUE) &&
    requireNamespace("spdep", quietly = TRUE)) {
  nc <- sf::st_read(system.file("shape/nc.shp", package = "sf"),
                    quiet = TRUE)
  W_nc <- slx_weights(nc, style = "contiguity")
  W_nc
}
#> <slx_W>  n = 100   style = contiguity   row-standardized = TRUE 
# }