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

All Known Subinterfaces:

GeometricLinkage

All Known Implementing Classes:

CentroidLinkage, CompleteLinkage, FlexibleBetaLinkage, GroupAverageLinkage, MedianLinkage, MinimumVarianceLinkage, SingleLinkage, WardLinkage, WeightedAverageLinkage
```
@Reference(authors="G. N. Lance, W. T. Williams",
           title="A general theory of classificatory sorting strategies 1. Hierarchical systems",
           booktitle="The Computer Journal 9.4",
           url="https://doi.org/10.1093/comjnl/9.4.373",
           bibkey="doi:10.1093/comjnl/9.4.373")
public interface Linkage
```
Abstract interface for implementing a new linkage method into hierarchical clustering.
Reference:
G. N. Lance, W. T. Williams
A general theory of classificatory sorting strategies
1. Hierarchical systems
The Computer Journal 9.4

Since:

0.6.0

Author:

Erich Schubert

Method Summary

All Methods Instance Methods Abstract Methods Default Methods
Modifier and Type	Method	Description
`double`	`combine(int sizex, double dx, int sizey, double dy, int sizej, double dxy)`	Compute combined linkage for two clusters.
`default double`	`initial(double d, boolean issquare)`	Initialization of the distance matrix.
`default double`	`restore(double d, boolean issquare)`	Restore a distance to the original scale.

- Method Detail
  - initial
```
default double initial(double d,
                       boolean issquare)
```
    Initialization of the distance matrix.
    
    Parameters:
    
    d - Distance
    
    issquare - Flag to indicate the input values are already squared
    
    Returns:
    
    Initial value
  - restore
```
default double restore(double d,
                       boolean issquare)
```
    Restore a distance to the original scale.
    
    Parameters:
    
    d - Distance
    
    issquare - Flag to indicate the input values were already squared
    
    Returns:
    
    Initial value
  - combine
```
double combine(int sizex,
               double dx,
               int sizey,
               double dy,
               int sizej,
               double dxy)
```
    Compute combined linkage for two clusters.
    
    Parameters:
    
    sizex - Size of first cluster x before merging
    
    dx - Distance of cluster x to j before merging
    
    sizey - Size of second cluster y before merging
    
    dy - Distance of cluster y to j before merging
    
    sizej - Size of candidate cluster j
    
    dxy - Distance between clusters x and y before merging
    
    Returns:
    
    Combined distance