## Class CyclicEdgeDistance

• All Implemented Interfaces:
`NormalizedPermutationDistanceMeasurer`, `NormalizedPermutationDistanceMeasurerDouble`, `PermutationDistanceMeasurer`, `PermutationDistanceMeasurerDouble`

```public final class CyclicEdgeDistance
extends Object
implements NormalizedPermutationDistanceMeasurer```
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 order-based 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
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 Detail

• #### CyclicEdgeDistance

`public CyclicEdgeDistance()`
Constructs the distance measurer as specified in the class documentation.
• ### Method Detail

• #### 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.