Class SquaredDeviationDistance

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

    public final class SquaredDeviationDistance
    extends Object
    Squared Deviation Distance:

    Squared Deviation distance is the sum of the squares of the positional deviations 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 squared deviations: 1^2 + 1^2 + 1^2 + 2^2 + 0^2 + 3^2 = 1 + 1 + 1 + 4 + 9 = 16.

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

    Squared deviation distance is described in:
    M. Sevaux and K. Sorensen, "Permutation distance measures for memetic algorithms with population management," The 6th Metaheuristics International Conference, August, 2005.

    • Constructor Detail

      • SquaredDeviationDistance

        public SquaredDeviationDistance()
        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.