Module org.cicirello.chips_n_salsa
Package org.cicirello.search.operators.bits

Class UniformCrossover

java.lang.Object
org.cicirello.search.operators.bits.UniformCrossover
All Implemented Interfaces:
Splittable<CrossoverOperator<BitVector>>, CrossoverOperator<BitVector>
public final class UniformCrossover extends Object implements CrossoverOperator<BitVector>
Implementation of uniform crossover, a classic crossover operator for BitVectors. In uniform crossover, instead of a fixed number of cross points, the crossover operator is controlled by a parameter, p, that is the probability that a bit is exchanged between the two parents. If the BitVectors are N bits in length, then N independent random decisions are made regarding whether to exchange each bit between the parents in forming the children. The expected number of bits exchanged between the parents during a single crossover event is thus p*N. The most common value for p=0.5, which leads to each child inheriting on average half of the bits from each of the two parents.

  • Constructor Summary

    Constructors
    Constructor
    Description
    UniformCrossover()
    Constructs a uniform crossover operator with a probability of exchanging each bit of p=0.5.
    UniformCrossover(double p)
    Constructs a uniform crossover operator.

  • Method Summary

    Modifier and Type
    Method
    Description
    void
    cross(BitVector c1, BitVector c2)
    Performs a crossover for an evolutionary algorithm, such that crossover forms two children from two parents.
    UniformCrossover
    split()
    Generates a functionally identical copy of this object, for use in multithreaded implementations of search algorithms.

    Methods inherited from class java.lang.Object

    clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

  • Constructor Details

    • UniformCrossover

      public UniformCrossover()
      Constructs a uniform crossover operator with a probability of exchanging each bit of p=0.5.

    • UniformCrossover

      public UniformCrossover(double p)
      Constructs a uniform crossover operator.
      Parameters:
      p - The per-bit probability of exchanging each bit between the parents in forming the children. The expected number of bits exchanged during a single call to cross(org.cicirello.search.representations.BitVector, org.cicirello.search.representations.BitVector) is thus p*N, where N is the length of the BitVector.

  • Method Details

    • cross

      public void cross(BitVector c1, BitVector c2)
      Performs a crossover for an evolutionary algorithm, such that crossover forms two children from two parents. Implementations of this method modify the parameters, transforming the parents into the children.
      Specified by:
      cross in interface CrossoverOperator<BitVector>
      Parameters:
      c1 - A candidate solution subject to the crossover. This method changes the state of c1.
      c2 - A candidate solution subject to the crossover. This method changes the state of c2.
      Throws:
      IllegalArgumentException - if c1.length() is not equal to c2.length()

    • split

      public UniformCrossover split()
      Description copied from interface: Splittable
      Generates a functionally identical copy of this object, for use in multithreaded implementations of search algorithms. The state of the object that is returned may or may not be identical to that of the original. Thus, this is a distinct concept from the functionality of the Copyable interface. Classes that implement this interface must ensure that the object returned performs the same functionality, and that it does not share any state data that would be either unsafe or inefficient for concurrent access by multiple threads. The split method is allowed to simply return the this reference, provided that it is both safe and efficient for multiple threads to share a single copy of the Splittable object. The intention is to provide a multithreaded search with the capability to provide spawned threads with their own distinct search operators. Such multithreaded algorithms can call the split method for each thread it spawns to generate a functionally identical copy of the operator, but with independent state.
      Specified by:
      split in interface Splittable<CrossoverOperator<BitVector>>
      Returns:
      A functionally identical copy of the object, or a reference to this if it is both safe and efficient for multiple threads to share a single instance of this Splittable object.