org.apache.commons.math3.genetics
Class OrderedCrossover<T>

java.lang.Object
  extended by org.apache.commons.math3.genetics.OrderedCrossover<T>
Type Parameters:
T - generic type of the AbstractListChromosomes for crossover
All Implemented Interfaces:
CrossoverPolicy

public class OrderedCrossover<T>
extends Object
implements CrossoverPolicy

Order 1 Crossover [OX1] builds offspring from ordered chromosomes by copying a consecutive slice from one parent, and filling up the remaining genes from the other parent as they appear.

This policy works by applying the following rules:

  1. select a random slice of consecutive genes from parent 1
  2. copy the slice to child 1 and mark out the genes in parent 2
  3. starting from the right side of the slice, copy genes from parent 2 as they appear to child 1 if they are not yet marked out.

Example (random sublist from index 3 to 7, underlined):

 p1 = (8 4 7 3 6 2 5 1 9 0)   X   c1 = (0 4 7 3 6 2 5 1 8 9)
             ---------                        ---------
 p2 = (0 1 2 3 4 5 6 7 8 9)   X   c2 = (8 1 2 3 4 5 6 7 9 0)
 

This policy works only on AbstractListChromosome, and therefore it is parameterized by T. Moreover, the chromosomes must have same lengths.

Since:
3.1
Version:
$Id: OrderedCrossover.java 1385297 2012-09-16 16:05:57Z tn $
See Also:
Order 1 Crossover Operator

Constructor Summary
OrderedCrossover()
           
 
Method Summary
 ChromosomePair crossover(Chromosome first, Chromosome second)
          Perform a crossover operation on the given chromosomes.
protected  ChromosomePair mate(AbstractListChromosome<T> first, AbstractListChromosome<T> second)
          Helper for crossover(Chromosome, Chromosome).
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Constructor Detail

OrderedCrossover

public OrderedCrossover()
Method Detail

crossover

public ChromosomePair crossover(Chromosome first,
                                Chromosome second)
                         throws DimensionMismatchException,
                                MathIllegalArgumentException
Perform a crossover operation on the given chromosomes.

Specified by:
crossover in interface CrossoverPolicy
Parameters:
first - the first chromosome.
second - the second chromosome.
Returns:
the pair of new chromosomes that resulted from the crossover.
Throws:
MathIllegalArgumentException - iff one of the chromosomes is not an instance of AbstractListChromosome
DimensionMismatchException - if the length of the two chromosomes is different

mate

protected ChromosomePair mate(AbstractListChromosome<T> first,
                              AbstractListChromosome<T> second)
                       throws DimensionMismatchException
Helper for crossover(Chromosome, Chromosome). Performs the actual crossover.

Parameters:
first - the first chromosome
second - the second chromosome
Returns:
the pair of new chromosomes that resulted from the crossover
Throws:
DimensionMismatchException - if the length of the two chromosomes is different


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