agnes(x, diss = inherits(x, "dist"),
metric = "euclidean", stand = FALSE, method = "average")
diss
argument.In case of a matrix or data frame, each row corresponds to an observation, and each column corresponds to a variable. All variables
dist
or
dissimilarity
objects), then x
is assumed to be a
dissimilarity matrix. If FALSE, then x
is treated as
a matrix of observations by variables.x
are
standardized before calculating the dissimilarities. Measurements
are standardized for each variable (column), by subtracting the
variable's mean value and dividing by the vari"agnes"
representing the clustering.
See agnes.object
for details.agnes
is fully described in chapter 5 of Kaufman and Rousseeuw (1990).
Compared to other agglomerative clustering methods such as hclust
,
agnes
has the following features: (a) it yields the
agglomerative coefficient (see agnes.object
)
which measures the amount of clustering structure found; and (b)
apart from the usual tree it also provides the banner, a novel
graphical display (see plot.agnes
). The agnes
-algorithm constructs a hierarchy of clusterings.
At first, each observation is a small cluster by itself. Clusters are
merged until only one large cluster remains which contains all the
observations. At each stage the two nearest clusters are combined
to form one larger cluster.
For method="average"
, the distance between two clusters is the
average of the dissimilarities between the points in one cluster and the
points in the other cluster.
In method="single"
, we use the smallest dissimilarity between a
point in the first cluster and a point in the second cluster (nearest
neighbor method).
When method="complete"
, we use the largest dissimilarity
between a point in the first cluster and a point in the second cluster
(furthest neighbor method).
Anja Struyf, Mia Hubert & Peter J. Rousseeuw (1996):
Clustering in an Object-Oriented Environment.
Journal of Statistical Software, 1.
Struyf, A., Hubert, M. and Rousseeuw, P.J. (1997). Integrating Robust Clustering Techniques in S-PLUS, Computational Statistics and Data Analysis, 26, 17--37.
agnes.object
, daisy
, diana
,
dist
, hclust
, plot.agnes
,
twins.object
.data(votes.repub)
agn1 <- agnes(votes.repub, metric = "manhattan", stand = TRUE)
agn1
plot(agn1)
agn2 <- agnes(daisy(votes.repub), diss = TRUE, method = "complete")
plot(agn2)
data(agriculture)
## Plot similar to Figure 7 in ref
plot(agnes(agriculture), ask = TRUE)
<testonly>plot(agnes(agriculture))</testonly>
Run the code above in your browser using DataLab