cluinf: Provide information about a hierarchical clustering

Description

Agglomerative hierarchical clustering procedures typically produce a list of the clusters merged at each stage of the clustering. cluinf uses this list to construct arrays that explicitly show which cluster a given data point belongs to, and which data points belong to a given cluster.

Usage

cluinf(merge, nclust)

Arguments

merge

Matrix with 2 columns. The $i$th row contains the labels of the clusters merged at the $i$th merge. Can also be the object returned by a call to cluagg.

nclust

Number of clusters.

Value

Information about the clustering that has nclust clusters. It is a list with the following elements:
assignVector giving the assignment of items to clusters.
listList with nclust elements. Each element contains the labels of the items in one cluster.
numVector of length nclust, containing the number of items in each cluster.

References

Hosking, J. R. M., and Wallis, J. R. (1997). Regional frequency analysis: an approach based on $L$-moments. Cambridge University Press.

Examples

Run this code

## Clustering of gaging stations in Appalachia, as in Hosking
## and Wallis (1997, sec. 9.2.3)
data(Appalach)
# Form attributes for clustering (Hosking and Wallis's Table 9.4)
att <- cbind(a1 = log(Appalach$area),
             a2 = sqrt(Appalach$elev),
             a3 = Appalach$lat,
             a4 = Appalach$long)
att <- apply(att, 2, function(x) x/sd(x))
att[,1] <- att[,1] * 3
# Clustering by Ward's method
(cl<-cluagg(att))
# Details of the clustering with 7 clusters
cluinf(cl, 7)