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% Copyright 2001 by Roger S. Bivand
\name{knn2nb}
\alias{knn2nb}
\title{Neighbours list from knn object}
\description{
The function converts a \code{knn} object returned by \code{knearneigh}
into a neighbours list of class \code{nb} with a list of integer vectors
containing neighbour region number ids.
}
\usage{
knn2nb(knn, row.names = NULL, sym = FALSE)
}
\arguments{
\item{knn}{A knn object returned by \code{knearneigh}}
\item{row.names}{character vector of region ids to be added to the neighbours list as attribute \code{region.id}, default \code{seq(1, nrow(x))}}
\item{sym}{force the output neighbours list to symmetry}
}
\value{
The function returns an object of class \code{nb} with a list of integer vectors containing neighbour region number ids. See \code{\link{card}} for details of \dQuote{nb} objects.
}
\author{Roger Bivand \email{Roger.Bivand@nhh.no}}
\seealso{\code{\link{knearneigh}}, \code{\link{card}}}
\examples{
if (require(rgdal, quietly=TRUE)) {
example(columbus, package="spData")
coords <- coordinates(columbus)
col.knn <- knearneigh(coords, k=4)
plot(columbus, border="grey")
plot(knn2nb(col.knn), coords, add=TRUE)
title(main="K nearest neighbours, k = 4")
}
}
\keyword{spatial}
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