TITLE(cmdscale @@ Classical (Metric) Multidimensional Scaling)
USAGE(
cmdscale(d, k=2, eig=FALSE)
)
ARGUMENTS(
ARG(d @@ a distance structure such as that returned by LANG(dist)
or a full symmetric matrix containing the dissimilarities.)
ARG(k @@ the dimension of the space which the data are to be represented in.)
ARG(eig @@ indicates whether eigenvalues should be returned.)
)
DESCRIPTION(
Multidimensional scaling takes a set of dissimilarities
and returns a set of points such that the distances between the points
are approximately equal to the dissimilarities.
PARA
The funtions LANG(isomds) and LANG(sammon) provide
alternative ordination techniques.
)
VALUES(
A list containing the following components.
@@
ARG(points @@ a matrix with LANG(k) columns whose rows give the
coordinates of the points chosen to represent the dissimilarities.)
ARG(eig @@ if requested,pthe eigenvalues computed during the scaling process.)
)
REFERENCES(
Seber, G. A. F. (1984).
ITALIC(Multivariate Analysis). New York: Wiley.
PARA
Torgerson, W. S. (1958).
ITALIC(Theory and Methods of Scaling).
New York: Wiley.
)
NOTE(
The S version of this function provides for computing an additional
``fiddle'' factor suggested by Togerson.  R does not provide this option.
)
SEEALSO(
LANG(LINK(dist)),
LANG(LINK(isomds)),
LANG(LINK(sammon)).
)
EXAMPLES(
data(eurodist)
loc <- cmdscale(eurodist)
x <- loc[,1]
y <- -loc[,2]
plot(x, y, type="n",
	xlim=c(-2500,2500), ylim=c(-2000,2000),
	xlab="", ylab="")
text(x, y, text=names(eurodist), cex=0.5)
)
