Short note on Dendrogram, AGNES (Agglomerative Nesting), DIANA (Divisive Analysis).

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 Dendrogram

Decompose data objects into several levels of nested partitioning (tree of clusters), called a dendrogram.

A clustering of the data objects is obtained by cutting the dendrogram at the desired level, then each connected component forms a cluster.

                                                                Figure:-  Dendrogram


AGNES (Agglomerative Nesting)

  •  Introduced in Kaufmann and Rousseeuw (1990)
  • Implemented in statistical analysis packages, e.g., Splus
  • Use the Single-Link method and the dissimilarity matrix.
  • Merge nodes that have the least dissimilarity
  • Go on in a non-descending fashion
  • Eventually, all nodes belong to the same cluster



DIANA (Divisive Analysis)

  • Introduced in Kaufmann and Rousseeuw (1990)
  • Implemented in statistical analysis packages, e.g., Splus
  • Inverse order of AGNES
  • Eventually, each node forms a cluster on its own.


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