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java.lang.Objectorg.apache.commons.math3.genetics.NPointCrossover<T>
T
- generic type of the AbstractListChromosome
s for crossoverpublic class NPointCrossover<T>
N-point crossover policy. For each iteration a random crossover point is selected and the first part from each parent is copied to the corresponding child, and the second parts are copied crosswise. 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)This policy works only on
AbstractListChromosome
, and therefore it
is parameterized by T. Moreover, the chromosomes must have same lengths.
Field Summary | |
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private int |
crossoverPoints
The number of crossover points. |
Constructor Summary | |
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NPointCrossover(int crossoverPoints)
Creates a new NPointCrossover policy using the given number of points. |
Method Summary | |
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ChromosomePair |
crossover(Chromosome first,
Chromosome second)
Performs a N-point crossover. |
int |
getCrossoverPoints()
Returns the number of crossover points used by this CrossoverPolicy . |
private 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 |
Field Detail |
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private final int crossoverPoints
Constructor Detail |
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public NPointCrossover(int crossoverPoints) throws NotStrictlyPositiveException
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.
crossoverPoints
- the number of crossover points
NotStrictlyPositiveException
- if the number of crossoverPoints
is not strictly positiveMethod Detail |
---|
public int getCrossoverPoints()
CrossoverPolicy
.
public ChromosomePair crossover(Chromosome first, Chromosome second) throws DimensionMismatchException, MathIllegalArgumentException
-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)
crossover
in interface CrossoverPolicy
first
- first parent (p1)second
- second parent (p2)
MathIllegalArgumentException
- iff one of the chromosomes is
not an instance of AbstractListChromosome
DimensionMismatchException
- if the length of the two chromosomes is differentprivate ChromosomePair mate(AbstractListChromosome<T> first, AbstractListChromosome<T> second) throws DimensionMismatchException, NumberIsTooLargeException
crossover(Chromosome, Chromosome)
. Performs the actual crossover.
first
- the first chromosomesecond
- the second chromosome
DimensionMismatchException
- if the length of the two chromosomes is different
NumberIsTooLargeException
- if the number of crossoverPoints is too large for the actual chromosomes
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