Problem

Clustering auto posts. In this problem, you will use the data and scenario described in this chapter's example. The task is to cluster the auto posts.

a. Following the example in this chapter, preprocess the documents, except do not create a label vector.

b. Use the ls a package to create 10 concepts.

c. Before doing the clustering, state how many natural clusters you expect to find.

d. Perform hierarchical clustering and inspect the dendrogram.

i. From the dendrogram, how many natural clusters appear?

ii. Examining the dendrogram as it branches beyond the number of main clusters, select a sub-cluster and assess its characteristics.

e. Perform k-means clustering for two clusters and report how distant and separated they are (using between-cluster distance and within cluster dispersion).