Class Ai4r::Clusterers::MedianLinkage
In: lib/ai4r/clusterers/median_linkage.rb
Parent: SingleLinkage

Implementation of an Agglomerative Hierarchical clusterer with median linkage algorithm, aka weighted pair group method centroid or WPGMC (Everitt et al., 2001 ; Gower, 1967 ; Jain and Dubes, 1988 ). Hierarchical clusteres create one cluster per element, and then progressively merge clusters, until the required number of clusters is reached. Similar to centroid linkages, but using fix weight:

  D(cx, (ci U cj)) =  (1/2)*D(cx, ci) +
                      (1/2)*D(cx, cj) -
                      (1/4)*D(ci, cj)

Methods

Public Instance methods

Build a new clusterer, using data examples found in data_set. Items will be clustered in "number_of_clusters" different clusters.

This algorithms does not allow classification of new data items once it has been built. Rebuild the cluster including you data element.

Protected Instance methods

return distance between cluster cx and cluster (ci U cj), using median linkage

[Validate]