Agglomerative Nesting Object

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DESCRIPTION:

These are objects of class "agnes" They represent an agglomerative hierarchical clustering of a dataset.

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GENERATION:

This class of objects is returned from agnes.

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METHODS:

The "agnes" class has methods for the following generic functions: print, summary, plot, pltree.

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STRUCTURE:

A legitimate agnes object is a list with the following components:

order:

a vector giving a permutation of the original objects to allow for plotting, in the sense that the branches of a clustering tree will not cross.

height:

a vector with the distances between merging clusters at the successive stages.

ac:

the agglomerative coefficient, measuring the clustering structure of the dataset. For each object i, denote by m(i) its dissimilarity to the first cluster it is merged with, divided by the dissimilarity of the merger in the final step of the algorithm. The ac is the average of all 1 - m(i). It can also be seen as the average width (or the percentage filled) of the banner plot. Because ac grows with the number of objects, this measure should not be used to compare datasets of very different sizes.

merge:

an (n-1) by 2 matrix, where n is the number of objects. Row i of merge describes the merging of clusters at step i of the clustering. If a number j in the row is negative, then the single object |j| is merged at this stage. If j is positive, then the merger is with the cluster formed at stage j of the algorithm.

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SEE ALSO:

agnes , diana , hclust , plot.agnes , pltree.agnes .