Hierarchical Clustering in R

In this post, I will show you how to do hierarchical clustering in R. We will use the iris dataset again, like we did for K means clustering. If you recall from the post about k means clustering, it requires us to specify the number of clusters, and finding the optimal number of clusters can often be hard. Hierarchical clustering is an alternative approach which builds a hierarchy from the bottom-up, and doesn't require us to specify the number of clusters beforehand. Once this is done, it is usually represented by a dendrogram like structure. Complete linkage and mean linkage clustering are the ones used most often.