\name{gg}
\alias{gg}
\title{ Gabriel Graph}
\description{
A Gabriel graph is one where the vertices are points and there
is an edge between two points if the maximal ball between the points
contains no other points.
}
\usage{
gg(x, r = 1, method = NULL, usedeldir = TRUE)
}
\arguments{
\item{x}{ a matrix of observations.}
\item{r}{ a multiplier on the ball radius.}
\item{method}{ the method used for the distance.
See \code{\link[proxy]{dist}}}
\item{usedeldir}{logical. Whether to use the deldir package or not.}
}
\details{
places an edge between two points \eqn{i,j} if the ball centered between
the points with radius \eqn{r d(i,j)/2} contains no other points.
}
\value{
an object of class igraph. In addition it contains the attributes:
\item{layout}{ the data.}
\item{r,p}{arguments passed to \code{gg}}
}
\references{
K.R. Gabriel and R.R. Sokal,
A New Statistical Approach to Geographic Variation Analysis,
Systemic Zoology, 18, 259-278, 1969
D.J. Marchette, Random Graphs for Statistical Pattern Recognition,
John Wiley & Sons, 2004.
}
\author{ David J. Marchette}
\seealso{ \code{\link{rng}}, \code{\link[proxy]{dist}}}
\examples{
x <- matrix(runif(100),ncol=2)
g <- gg(x)
\dontrun{
plot(g)
}
}
\keyword{ graphs }