Class CyclicRTypeDistance

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

    public final class CyclicRTypeDistance
    extends Object
    Cyclic RType Distance:

    Cyclic RType distance treats the permutations as if they represent sets of directed 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 RType distance treats this as equivalent to the set of directed 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 4. Why? Well, the first permutation has the directed edges: {(1,5), (5,2), (2,4), (4,0), (0,3), (3,1)}. The second has 2 of these (4,0), and (0,3), but does not include 4 of the edges: (1,5), (5,2), (2,4), (3,1)

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

    Cyclic RType distance was introduced in:
    V.A. Cicirello, "The Permutation in a Haystack Problem and the Calculus of Search Landscapes," IEEE Transactions on Evolutionary Computation, 20(3):434-446, June 2016.

    • Constructor Detail

      • CyclicRTypeDistance

        public CyclicRTypeDistance()
        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.
        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.
        Parameters:
        length - Permutation length.
        Returns:
        the maximum distance between a pair of permutations of the specified length.