Apache Commons Math 3.6.1 · org.apache.commons.math3.genetics.NPointCrossover

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

Modifier and Type	Field and Description
private final int	crossoverPoints The number of crossover points.

Constructor Summary

Access	Constructor and Description
public	NPointCrossover(final int the number of crossover points crossoverPoints) Creates a new `NPointCrossover` policy using the given number of points.

Method Summary

Modifier and Type	Method and Description
public ChromosomePair	Returns: pair of two children (c1,c2) crossover(final Chromosome first parent (p1) first, final Chromosome second parent (p2) second) Implements org.apache.commons.math3.genetics.CrossoverPolicy.crossover. Performs a N-point crossover.
public int	Returns: the number of crossover points getCrossoverPoints() Returns the number of crossover points used by this `CrossoverPolicy`.
private ChromosomePair	Returns: the pair of new chromosomes that resulted from the crossover mate(final AbstractListChromosome<T> the first chromosome first, final AbstractListChromosome<T> the second chromosome second) Helper for `crossover(Chromosome, Chromosome)`.

Inherited from java.lang.Object:: clone equals finalize getClass hashCode notify notifyAll toString wait wait wait

Field Detail

crossoverPoints	back to summary
private final int crossoverPoints The number of crossover points.

Constructor Detail

NPointCrossover back to summary

NPointCrossover	back to summary
public NPointCrossover(final 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:int the number of crossover points Exceptions NotStrictlyPositiveException: if the number of `crossoverPoints` is not strictly positive

public NPointCrossover(final 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:int: the number of crossover points

Exceptions

NotStrictlyPositiveException:: if the number of crossoverPoints is not strictly positive

Method Detail

crossover back to summary

crossover	back to summary
public ChromosomePair crossover(final Chromosome first, final Chromosome second) throws DimensionMismatchException, MathIllegalArgumentException Implements org.apache.commons.math3.genetics.CrossoverPolicy.crossover. 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) Parameters first:Chromosome first parent (p1) second:Chromosome second parent (p2) Returns:ChromosomePair pair of two children (c1,c2) Annotations @SuppressWarnings:unchecked Exceptions DimensionMismatchException: if the length of the two chromosomes is different MathIllegalArgumentException: iff one of the chromosomes is not an instance of `AbstractListChromosome`

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

Implements org.apache.commons.math3.genetics.CrossoverPolicy.crossover.

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)

Parameters

first:Chromosome: first parent (p1)
second:Chromosome: second parent (p2)

Returns:ChromosomePair

pair of two children (c1,c2)

Annotations

@SuppressWarnings:unchecked

Exceptions

DimensionMismatchException:: if the length of the two chromosomes is different
MathIllegalArgumentException:: iff one of the chromosomes is not an instance of AbstractListChromosome

getCrossoverPoints back to summary

getCrossoverPoints	back to summary
public int getCrossoverPoints() Returns the number of crossover points used by this `CrossoverPolicy`. Returns:int the number of crossover points

public int getCrossoverPoints()

Returns the number of crossover points used by this CrossoverPolicy.

Returns:int: the number of crossover points

mate back to summary

mate	back to summary
private ChromosomePair mate(final AbstractListChromosome<T> first, final AbstractListChromosome<T> second) throws DimensionMismatchException, NumberIsTooLargeException Helper for `crossover(Chromosome, Chromosome)`. Performs the actual crossover. Parameters first:AbstractListChromosome<T> the first chromosome second:AbstractListChromosome<T> the second chromosome Returns:ChromosomePair the pair of new chromosomes that resulted from the crossover Exceptions DimensionMismatchException: if the length of the two chromosomes is different NumberIsTooLargeException: if the number of crossoverPoints is too large for the actual chromosomes

private ChromosomePair mate(final AbstractListChromosome<T> first, final AbstractListChromosome<T> second) throws DimensionMismatchException, NumberIsTooLargeException

Helper for crossover(Chromosome, Chromosome). Performs the actual crossover.

Parameters

first:AbstractListChromosome<T>: the first chromosome
second:AbstractListChromosome<T>: the second chromosome

Returns:ChromosomePair

the pair of new chromosomes that resulted from the crossover

Exceptions

DimensionMismatchException:: if the length of the two chromosomes is different
NumberIsTooLargeException:: if the number of crossoverPoints is too large for the actual chromosomes

public Class NPointCrossover<T>

Field Summary

Constructor Summary

Method Summary

Field Detail

Constructor Detail

Method Detail