Two types
1. Agglomerative
2. Divisive
We use Agglomerative Hierarchical Clustering Technique(i.e Bottom Up Approach)
Steps :
---> Make each data point a single-point cluster.That forms N-Clusters.
---> Take the two closest data points and make them one cluster.That form N-1.
---> Take the two closest clusters and make them one cluster.That forms N-2 Clusters.
---> Repeat above step until there is only one cluster.
---> Finally, all the clusters are merged together and form a single cluster.
- The Hierarchical clustering Technique can be visualized using a Dendrogram.
---> By crossing the largest distance vertical line in dendogarm we will get the optimal number of clusters.