Module org.cicirello.jpt

Package org.cicirello.permutations.distance

Class DeviationDistance

java.lang.Object

org.cicirello.permutations.distance.DeviationDistance

All Implemented Interfaces:

NormalizedPermutationDistanceMeasurer, NormalizedPermutationDistanceMeasurerDouble, PermutationDistanceMeasurer, PermutationDistanceMeasurerDouble

public final class DeviationDistance
extends Object
implements NormalizedPermutationDistanceMeasurer

Deviation distance is the sum of the positional deviation of the permutation elements. The positional deviation of an element is the difference in its location in the two permutations.

For example, consider p1 = [0, 1, 2, 3, 4, 5] and p2 = [1, 0, 5, 2, 4, 3]. Element 0 is displaced by 1 position. Likewise for elements 1 and 2. Element 3 is displaced by 2 positions. Element 4 is in the same position in both. Element 5 is displaced by 3 positions.

Sum the deviations: 1 + 1 + 1 + 2 + 0 + 3 = 8. And that is the distance.

Runtime: O(n), where n is the permutation length.

Deviation distance was introduced in:
S. Ronald, "More distance functions for order-based encodings," in Proc. IEEE CEC. IEEE Press, 1998, pp. 558–563.

Constructor Summary

Constructors

Constructor	Description
DeviationDistance()	Constructs the distance measurer as specified in the class documentation.

Method Summary

Modifier and Type	Method	Description
int	distance(Permutation p1, Permutation p2)	Measures the distance between two permutations.
int	max(int length)	Computes the maximum possible distance between permutations of a specified length.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface org.cicirello.permutations.distance.NormalizedPermutationDistanceMeasurer

maxf, normalizedDistance

Methods inherited from interface org.cicirello.permutations.distance.PermutationDistanceMeasurer

distancef

Constructor Details

DeviationDistance

public DeviationDistance()

Constructs the distance measurer as specified in the class documentation.

Method Details

distance

public int distance(Permutation p1,
 Permutation p2)

Measures the distance between two permutations.

Specified by:

distance in interface PermutationDistanceMeasurer

Parameters:

p1 - first permutation

p2 - second permutation

Returns:

distance between p1 and p2

Throws:

IllegalArgumentException - if p1.length() is not equal to p2.length().

max

public int max(int length)

Description copied from interface: NormalizedPermutationDistanceMeasurer

Computes the maximum possible distance between permutations of a specified length.

Specified by:

max in interface NormalizedPermutationDistanceMeasurer

Parameters:

length - Permutation length.

Returns:

the maximum distance between a pair of permutations of the specified length.