cluinf function

Provide information about a hierarchical clustering

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.

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.

Returns

Information about the clustering that has nclust clusters. It is a list with the following elements: - assign: Vector giving the assignment of items to clusters.

• list: List with nclust elements. Each element contains the labels of the items in one cluster.

• num: Vector 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.

Author(s)

J. R. M. Hosking jrmhosking@gmail.com

See Also

cluagg

Examples

## 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)