Perform the following steps to visualize the dissimilarity matrix:

1. First, install and load the seriation package:

        > install.packages("seriation")
        > library(seriation)

2. You can then use dissplot to visualize the dissimilarity matrix in a heat map:

        > dissplot(dist(customer), labels=km$cluster,
        options=list(main="Kmeans Clustering With k=4"))

3. Next, apply dissplot on hierarchical clustering in the heat map:

        > complete_c =  hclust(dist(customer), method="complete")
        > hc_complete =  cutree(complete_c, k = 4)
        > dissplot(dist(customer), labels=hc_complete,
        options=list(main="Hierarchical Clustering"))