EvaluateRankingQuality (ELKI: Environment for DeveLoping KDD-Applications Supported by Index-Structures)

java.lang.Object
- elki.algorithm.statistics.EvaluateRankingQuality<V>

Type Parameters:

V - Vector type

All Implemented Interfaces:

Algorithm
```
@Title("Evaluate Ranking Quality")
@Description("Evaluates the effectiveness of a distance function via the obtained rankings.")
public class EvaluateRankingQuality<V extends NumberVector>
extends java.lang.Object
implements Algorithm
```
Evaluate a distance function with respect to kNN queries. For each point, the neighbors are sorted by distance, then the AUROC is computed. A score of 1 means that the distance function provides a perfect ordering of relevant neighbors first, then irrelevant neighbors. A value of 0.5 can be obtained by random sorting. A value of 0 means the distance function is inverted, i.e. a similarity.
In contrast to RankingQualityHistogram, this method uses a binning based on the centrality of objects. This allows analyzing whether or not a particular distance degrades for the outer parts of a cluster.
TODO: Allow fixed binning range, configurable
TODO: Add sampling

Since:

0.2

Author:

Erich Schubert

Nested Class Summary
- Nested classes/interfaces inherited from interface elki.Algorithm
  Algorithm.Utils

Field Summary

Fields
Modifier and Type	Field	Description
`protected Distance<? super V>`	`distance`	Distance function used.
`private static Logging`	`LOG`	The logger for this class.
`protected int`	`numbins`	Number of bins to use.

Constructor Summary

Constructors
Constructor Description

EvaluateRankingQuality(Distance<? super V> distance, int numbins)
Constructor.

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`TypeInformation[]`	`getInputTypeRestriction()`	Get the input type restriction used for negotiating the data query.
`HistogramResult`	`run(Database database, Relation<V> relation)`	Run the algorithm.

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

Methods inherited from interface elki.Algorithm
autorun

- Field Detail
  - LOG
```
private static final Logging LOG
```
    The logger for this class.
  - distance
```
protected Distance<? super V extends NumberVector> distance
```
    Distance function used.
  - numbins
```
protected int numbins
```
    Number of bins to use.
- Constructor Detail
  - EvaluateRankingQuality
```
public EvaluateRankingQuality(Distance<? super V> distance,
                              int numbins)
```
    Constructor.
    
    Parameters:
    
    distance - Distance function
    
    numbins - Number of bins
- Method Detail
  - getInputTypeRestriction
```
public TypeInformation[] getInputTypeRestriction()
```
    Description copied from interface: Algorithm
    
    Get the input type restriction used for negotiating the data query.
    
    Specified by:
    
    getInputTypeRestriction in interface Algorithm
    
    Returns:
    
    Type restriction
  - run
```
public HistogramResult run(Database database,
                           Relation<V> relation)
```
    Run the algorithm.
    
    Parameters:
    
    database - Database
    
    relation - Relation
    
    Returns:
    
    Histogram