Class CyclicEdgeDistance
 java.lang.Object

 org.cicirello.permutations.distance.CyclicEdgeDistance

 All Implemented Interfaces:
NormalizedPermutationDistanceMeasurer
,NormalizedPermutationDistanceMeasurerDouble
,PermutationDistanceMeasurer
,PermutationDistanceMeasurerDouble
public final class CyclicEdgeDistance extends Object
Cyclic Edge Distance:Cyclic edge distance treats the permutations as if they represent sets of edges, and counts the number of edges that differ. It treats the last to the first element as an edge.
Consider the example permutation: [1, 5, 2, 4, 0, 3]. Cyclic edge distance treats this as equivalent to the set of undirected edges: {(1,5), (5,2), (2,4), (4,0), (0,3), (3,1)}.
E.g., distance between [1, 5, 2, 4, 0, 3] and [ 5, 1, 4, 0, 3, 2] is 3. Why? Well, the first permutation has the edges: {(1,5), (5,2), (2,4), (4,0), (0,3), (3,1)}. The second has three of these (5,1), which is the same as (1,5) since they are undirected edges, (4,0), and (0,3), but does not include 3 of the edges: (5,2), (2,4), (3,1)
Runtime: O(n), where n is the permutation length.
Cyclic edge distance was first described in:
S. Ronald, "Distance functions for orderbased encodings," in Proc. IEEE CEC. IEEE Press, 1997, pp. 49–54.


Constructor Summary
Constructors Constructor Description CyclicEdgeDistance()
Constructs the distance measurer as specified in the class documentation.

Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description int
distance(Permutation p1, Permutation p2)
Measures the distance between two permutations.double
distancef(Permutation p1, Permutation p2)
Measures the distance between two permutationsint
max(int length)
Computes the maximum possible distance between permutations of a specified length.double
maxf(int length)
Computes the maximum possible distance between permutations of a specified length.double
normalizedDistance(Permutation p1, Permutation p2)
Measures the distance between two permutations, normalized to the interval [0.0, 1.0].



Method Detail

distance
public int distance(Permutation p1, Permutation p2)
Measures the distance between two permutations. Parameters:
p1
 first permutationp2
 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. Parameters:
length
 Permutation length. Returns:
 the maximum distance between a pair of permutations of the specified length.

distancef
public final double distancef(Permutation p1, Permutation p2)
Measures the distance between two permutations Specified by:
distancef
in interfacePermutationDistanceMeasurerDouble
 Parameters:
p1
 first permutationp2
 second permutation Returns:
 distance between p1 and p2
 Throws:
IllegalArgumentException
 if p1.length() is not equal to p2.length().

maxf
public final double maxf(int length)
Description copied from interface:NormalizedPermutationDistanceMeasurerDouble
Computes the maximum possible distance between permutations of a specified length. Specified by:
maxf
in interfaceNormalizedPermutationDistanceMeasurerDouble
 Parameters:
length
 Permutation length. Returns:
 the maximum distance between a pair of permutations of the specified length.

normalizedDistance
public final double normalizedDistance(Permutation p1, Permutation p2)
Measures the distance between two permutations, normalized to the interval [0.0, 1.0].
 Specified by:
normalizedDistance
in interfaceNormalizedPermutationDistanceMeasurerDouble
 Parameters:
p1
 first permutationp2
 second permutation Returns:
 distance between p1 and p2 normalized to the interval [0.0, 1.0]
 Throws:
IllegalArgumentException
 if p1.length() is not equal to p2.length().

