SumOfClusterVariances (Apache Commons Math 4.0-beta1)

java.lang.Object
- org.apache.commons.math4.legacy.ml.clustering.evaluation.SumOfClusterVariances

All Implemented Interfaces:

ClusterEvaluator
```
public class SumOfClusterVariances
extends Object
implements ClusterEvaluator
```
Computes the sum of intra-cluster distance variances according to the formula:
```
 \( score = \sum\limits_{i=1}^n \sigma_i^2 \)
 
```
where n is the number of clusters and \( \sigma_i^2 \) is the variance of intra-cluster distances of cluster \( c_i \).
Since:

3.3

Constructor Summary

Constructors
Constructor Description

SumOfClusterVariances(DistanceMeasure measure)

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`boolean`	`isBetterScore(double a, double b)`	Provides a means to interpret the `score value`.
`double`	`score(List<? extends Cluster<? extends Clusterable>> clusters)`

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Constructor Detail
  - SumOfClusterVariances
```
public SumOfClusterVariances(DistanceMeasure measure)
```
    Parameters:
    
    measure - Distance measure.
- Method Detail
  - score
```
public double score(List<? extends Cluster<? extends Clusterable>> clusters)
```
    Specified by:
    
    score in interface ClusterEvaluator
    
    Parameters:
    
    clusters - List of clusters.
    
    Returns:
    
    the score attributed by the evaluator.
  - isBetterScore
```
public boolean isBetterScore(double a,
                             double b)
```
    Provides a means to interpret the score value.
    
    Specified by:
    
    isBetterScore in interface ClusterEvaluator
    
    Parameters:
    
    a - Score computed by this evaluator.
    
    b - Score computed by this evaluator.
    
    Returns:
    
    true if the evaluator considers that score a is better than score b.