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IndexPartitionDaviesBouldinIndex Method

Computes the Davies-Bouldin index to assess the quality of a given partition of the specified data.

Namespace:  Novacta.Analytics
Assembly:  Novacta.Analytics (in Novacta.Analytics.dll) Version: 2.0.0
Syntax
public static double DaviesBouldinIndex(
	DoubleMatrix data,
	IndexPartition<double> partition
)

Parameters

data
Type: Novacta.AnalyticsDoubleMatrix
The data whose rows represent the available observations.
partition
Type: Novacta.AnalyticsIndexPartitionDouble
The data partition to evaluate.

Return Value

Type: Double
The Davies Bouldin Index for the given data partition.
Exceptions
ExceptionCondition
ArgumentNullExceptiondata.
-or-
partition is null.
ArgumentException A part in partition contains a position which is not valid as a row index of data.
Remarks

Each column of data is associated to one of the variables under study, while its rows are associated to the individuals. The partition is intended to define parts which contains row indexes valid for data.

The Davies-Bouldin index takes on small values for partitions with high similarity among observations in each part and low similarities among parts. As a consequence, the best partition is considered the one with the smallest Davies–Bouldin index.

This method applies Euclidean distances. The intra-cluster distance is implemented as the centroid diameter, or the average distance between the elements in the cluster and the cluster centroid. The inter-cluster distance is implemented as the centroid linkage, i.e. the distance between cluster centroids.

See Also