spdep (version 1.2-4)

grid2nb: Construct neighbours for a GridTopology

Description

The function builds a neighbours list for a grid topology. It works for a k-dimentional grid topology, k>=1.

Usage

grid2nb(grid, d = [e-mail],
        queen = TRUE, nb = TRUE, self = FALSE)

Value

Either a matrix, if “nb” is FALSE or a neighbours list with class nb. See card for details of “nb”

objects.

Arguments

grid

An object of class GridTopology. One can avoid to supply this by just suplying the dimentions in the d argument.

d

A scalar (for one dimentional grid) or a length k vector specyfying the number of grid cells in each direction of the k dimentions.

queen

Logical. Default is TRUE. To inform if the queen neighbourhood structure should be considered. If FALSE, only a hyper-cube with a common face will be considered neighbour. If TRUE, a single shared coordinate meets the contiguity condition.

nb

Default TRUE. If TRUE, return the result as a neighbours list with class nb. If FALSE, the result is a matrix with 3^k columns if self = TRUE or 3^k-1 if self = FALSE. Zeros are used for hyper-cubes at boundaries.

self

Default FALSE, to indicate if the hyper-cube neighbour itself should be considered a neighbour.

Author

Elias T Krainski

See Also

poly2nb, summary.nb, card

Examples

nb <- grid2nb(d = c(5L, 5L, 5L))
nb
summary(nb)

gt <- GridTopology(c(.125,.1), c(.25,.2), c(4L, 5L))
nb1 <- grid2nb(gt, queen = FALSE)
nb2 <- grid2nb(gt)

sg <- SpatialGrid(gt)
plot(sg, lwd=3)
plot(nb1, coordinates(sg), add=TRUE, lty=2, col=2, lwd=2)
plot(nb2, coordinates(sg), add=TRUE, lty=3, col=4)

str(grid2nb(d=5))