cell2nb {spdep}R Documentation

Generate neighbours list for grid cells

Description

The function generates a list of neighbours for a grid of cells. Helper functions are used to convert to and from the vector indices for row and column grid positions, and rook (shared edge) or queen (shared edge or vertex) neighbour definitions are applied by type. If torus is TRUE, the grid is mapped onto a torus, removing edge effects.

Usage

cell2nb(nrow, ncol, type="rook", torus=FALSE)
mrc2vi(rowcol, nrow, ncol)
rookcell(rowcol, nrow, ncol, torus=FALSE, rmin=1, cmin=1)
queencell(rowcol, nrow, ncol, torus=FALSE, rmin=1, cmin=1)
vi2mrc(i, nrow, ncol)

Arguments

nrow number of rows in the grid
ncol number of columns in the grid
type rook or queen
torus map grid onto torus
rowcol matrix with two columns of row, column indices
i vector of vector indices corresponding to rowcol
rmin lowest row index
cmin lowset column index

Value

The function returns an object of class nb with a list of integer vectors containing neighbour region number ids.

Author(s)

Roger Bivand Roger.Bivand@nhh.no

See Also

summary.nb

Examples

nb7rt <- cell2nb(7, 7)
summary(nb7rt)
xyc <- attr(nb7rt, "region.id")
xy <- matrix(as.integer(unlist(strsplit(xyc, ":"))), ncol=2, byrow=TRUE)
plot(nb7rt, xy)
nb7rt <- cell2nb(7, 7, torus=TRUE)
summary(nb7rt)

[Package spdep version 0.3-12 Index]