rng.R
rng <- function(x=NULL,dx=NULL,r=1, method=NULL,usedeldir=TRUE)
{
if(is.null(dx)) {
if(is.null(x)) stop("One of x or dx must be given.")
dx <- as.matrix(dist(x,method=method))
}
n <- nrow(dx)
A <- matrix(0,nrow=n,ncol=n)
if(is.vector(x)) x <- matrix(x,ncol=1)
if(!require(deldir,quietly=TRUE)) usedeldir <- FALSE
if(usedeldir && ncol(x)==2){
del <- deldir(x[,1],x[,2])
for(edge in 1:nrow(del$delsgs)){
i <- del$delsgs[edge,5]
j <- del$delsgs[edge,6]
d <- min(apply(cbind(dx[i,-c(i,j)],dx[j,-c(i,j)]),1,max))
if(r*dx[i,j] < d){
A[i,j] <- 1
A[j,i] <- 1
}
}
}
else{
diag(dx) <- Inf
for(i in 1:n){
for(j in setdiff(1:n,i)){
d <- min(apply(cbind(dx[i,-c(i,j)],dx[j,-c(i,j)]),1,max))
if(r*dx[i,j] < d){
A[i,j] <- 1
A[j,i] <- 1
}
}
}
}
diag(A) <- 0
out <- graph.adjacency(A,mode="undirected")
out$layout <- x
out$r <- r
out
}