1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
|
\name{grid2nb}
\alias{grid2nb}
\title{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 = grid@cells.dim,
queen = TRUE, nb = TRUE, self = FALSE)
}
\arguments{
\item{grid}{An object of class \code{GridTopology}. One can avoid to
supply this by just suplying the dimentions in the \code{d} argument.}
\item{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.}
\item{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.}
\item{nb}{Default TRUE. If TRUE, return the result as a neighbours
list with class \code{nb}. If FALSE, the result is a matrix with
\code{3^k} columns if \code{self = TRUE} or \code{3^k-1} if
\code{self = FALSE}. Zeros are used for hyper-cubes at boundaries.}
\item{self}{Default FALSE, to indicate if the hyper-cube neighbour
itself should be considered a neighbour.}
}
\value{
Either a matrix, if \dQuote{nb} is FALSE or a neighbours list with
class \code{nb}. See \code{\link{card}} for details of \dQuote{nb}
objects.}
\note{
This applies to a k-dimentional grid topology.
}
\author{Elias T Krainski \email{eliaskrainski@gmail.com}}
\seealso{\code{\link{poly2nb}}, \code{\link{summary.nb}},
\code{\link{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))
}
\keyword{spatial}
|
