cell2nb: Generate neighbours list for grid cells

In spdep: Spatial Dependence: Weighting Schemes, Statistics and Models

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. See card for details of “nb” objects.

Author(s)

Roger Bivand [e-mail]

See Also

summary.nb, card

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)

Example output

Loading required package: sp
Loading required package: Matrix
Neighbour list object:
Number of regions: 49 
Number of nonzero links: 168 
Percentage nonzero weights: 6.997085 
Average number of links: 3.428571 
Link number distribution:

 2  3  4 
 4 20 25 
4 least connected regions:
1:1 7:1 1:7 7:7 with 2 links
25 most connected regions:
2:2 3:2 4:2 5:2 6:2 2:3 3:3 4:3 5:3 6:3 2:4 3:4 4:4 5:4 6:4 2:5 3:5 4:5 5:5 6:5 2:6 3:6 4:6 5:6 6:6 with 4 links
Neighbour list object:
Number of regions: 49 
Number of nonzero links: 196 
Percentage nonzero weights: 8.163265 
Average number of links: 4 
Link number distribution:

 4 
49 
49 least connected regions:
1:1 2:1 3:1 4:1 5:1 6:1 7:1 1:2 2:2 3:2 4:2 5:2 6:2 7:2 1:3 2:3 3:3 4:3 5:3 6:3 7:3 1:4 2:4 3:4 4:4 5:4 6:4 7:4 1:5 2:5 3:5 4:5 5:5 6:5 7:5 1:6 2:6 3:6 4:6 5:6 6:6 7:6 1:7 2:7 3:7 4:7 5:7 6:7 7:7 with 4 links
49 most connected regions:
1:1 2:1 3:1 4:1 5:1 6:1 7:1 1:2 2:2 3:2 4:2 5:2 6:2 7:2 1:3 2:3 3:3 4:3 5:3 6:3 7:3 1:4 2:4 3:4 4:4 5:4 6:4 7:4 1:5 2:5 3:5 4:5 5:5 6:5 7:5 1:6 2:6 3:6 4:6 5:6 6:6 7:6 1:7 2:7 3:7 4:7 5:7 6:7 7:7 with 4 links

spdep documentation built on Aug. 19, 2017, 3:01 a.m.