Module org.cicirello.jpt

Package org.cicirello.permutations.distance

Class CycleEditDistance

java.lang.Object

org.cicirello.permutations.distance.CycleEditDistance

All Implemented Interfaces:

NormalizedPermutationDistanceMeasurer, NormalizedPermutationDistanceMeasurerDouble, PermutationDistanceMeasurer, PermutationDistanceMeasurerDouble

public final class CycleEditDistance
extends Object
implements NormalizedPermutationDistanceMeasurer

Cycle edit distance is the minimum number of non-singleton permutation cycles necessary to transform permutation p1 into p2. If p1 equals p2, then this distance is 0. If p1 and p2 have a single permutation cycle, then this distance is clearly 1 since the inverse of that cycle will produce n fixed points. Otherwise, this distance is equal to 2 since it can be shown that at most 2 permutation cycle operations are necessary to transform any permutation of length n into any other. Cycle edit distance satisfies all of the metric properties.

Cycle edit distance was introduced in the following article:

Vincent A. Cicirello. 2022. Cycle Mutation: Evolving Permutations via Cycle Induction, Applied Sciences, 12(11), Article 5506 (June 2022). doi:10.3390/app12115506

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

Constructor Summary

Constructors

Constructor	Description
CycleEditDistance()	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

CycleEditDistance

public CycleEditDistance()

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.