Class: Ai4r::Clusterers::AverageLinkage

Inherits:
SingleLinkage show all
Includes:
ClusterTree
Defined in:
lib/ai4r/clusterers/average_linkage.rb

Overview

Implementation of a Hierarchical clusterer with group average linkage, AKA unweighted pair group method average or UPGMA (Everitt et al., 2001 ; Jain and Dubes, 1988 ; Sokal and Michener, 1958). Hierarchical clusterer create one cluster per element, and then progressively merge clusters, until the required number of clusters is reached. With average linkage, the distance between a clusters cx and cluster (ci U cj) the the average distance between cx and ci, and cx and cj.

D(cx, (ci U cj) = (D(cx, ci) + D(cx, cj)) / 2

Instance Attribute Summary

Attributes included from ClusterTree

#cluster_tree

Attributes inherited from SingleLinkage

#clusters, #data_set, #number_of_clusters

Instance Method Summary collapse

Methods included from ClusterTree

#initialize

Methods inherited from SingleLinkage

#draw_map, #initialize, #silhouette

Methods included from Data::Parameterizable

#get_parameters, included, #set_parameters

Instance Method Details

#build(data_set, number_of_clusters = 1, **options) ⇒ Object

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

Parameters:

  • data_set (Object)
  • number_of_clusters (Object) (defaults to: 1)
  • *options (Object)

Returns:

  • (Object) 


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# File 'lib/ai4r/clusterers/average_linkage.rb', line 45

def build(data_set, number_of_clusters = 1, **options)
  super
end

#eval(_data_item) ⇒ Object

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

Parameters:

  • _data_item (Object)

Returns:

  • (Object)

Raises:

  • (NotImplementedError) 


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# File 'lib/ai4r/clusterers/average_linkage.rb', line 53

def eval(_data_item)
  raise NotImplementedError, 'Eval of new data is not supported by this algorithm.'
end

#supports_eval? ⇒ Object

Average linkage builds a dendrogram and cannot classify new data once built.

Returns:

  • (Object) 


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# File 'lib/ai4r/clusterers/average_linkage.rb', line 60

def supports_eval?
  false
end