Constructor Detail

• NPointCrossover

  public NPointCrossover(int crossoverPoints)
                  throws NotStrictlyPositiveException

  Creates a new NPointCrossover policy using the given number of points.

  Note: the number of crossover points must be < chromosome length - 1. This condition can only be checked at runtime, as the chromosome length is not known in advance.

  Parameters:

  crossoverPoints - the number of crossover points

  Throws:

  NotStrictlyPositiveException - if the number of crossoverPoints is not strictly positive

Method Detail

• getCrossoverPoints

  public int getCrossoverPoints()

  Returns the number of crossover points used by this CrossoverPolicy.

  Returns:

  the number of crossover points

• crossover

  public ChromosomePair crossover(Chromosome first,
                         Chromosome second)
                           throws DimensionMismatchException,
                                  MathIllegalArgumentException

  Performs a N-point crossover. N random crossover points are selected and are used to divide the parent chromosomes into segments. The segments are copied in alternate order from the two parents to the corresponding child chromosomes. Example (2-point crossover):

   -C- denotes a crossover point
             -C-       -C-                         -C-        -C-
   p1 = (1 0  | 1 0 0 1 | 0 1 1)    X    p2 = (0 1  | 1 0 1 0  | 1 1 1)
        \----/ \-------/ \-----/              \----/ \--------/ \-----/
          ||      (*)       ||                  ||      (**)       ||
          VV      (**)      VV                  VV      (*)        VV
        /----\ /--------\ /-----\             /----\ /--------\ /-----\
   c1 = (1 0  | 1 0 1 0  | 0 1 1)    X   c2 = (0 1  | 1 0 0 1  | 0 1 1)
   

  Specified by:

  crossover in interface CrossoverPolicy

  Parameters:

  first - first parent (p1)

  second - second parent (p2)

  Returns:

  pair of two children (c1,c2)

  Throws:

  MathIllegalArgumentException - iff one of the chromosomes is not an instance of AbstractListChromosome

  DimensionMismatchException - if the length of the two chromosomes is different