Class: Wallace::Operators::SpliceCrossoverOperator

Inherits:
Wallace::Operator show all
Defined in:
lib/operators/splice_crossover_operation.rb

Overview

The splice crossover operator takes two parents (which may have different length genomes), splits each into two substrings at random points (using a different point for each parent) before combining the four substrings into a pair of two substrings at random to produce two children.

Instance Method Summary collapse

Methods inherited from Wallace::Operator

#initialize, #produce

Constructor Details

This class inherits a constructor from Wallace::Operator

Instance Method Details

#operate(rng, inputs) ⇒ Object 



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# File 'lib/operators/splice_crossover_operation.rb', line 8

def operate(rng, inputs)

  # Do nothing if either string is shorter than length 2.
  return inputs if inputs[0].length <= 1 or inputs[1].length <= 1

  # Cut the two strings into four strings at a random
  # point such that the recombination of any two strings will result in
  # a legal string (a string whose length does not exceed the bounds).
  x, y = rng.rand(1...inputs[0].length), rng.rand(1...inputs[1].length)
  strings = [
    inputs[0][0...x],
    inputs[1][0...y],
    inputs[0][x...inputs[0].length],
    inputs[1][y...inputs[1].length]
  ]

  # given any A, B, C and D, it is given that:
  # min <= #(A+B) <= max
  # min <= #(C+D) <= max

  # we want to find an A, B, C, D, such that:
  # min <= #(A+D) <= max
  # min <= #(C+B) <= max

  # Randomly re-attach the four strings into two strings
  # and return the resulting individuals.
  strings.shuffle!(random: rng)
  return [
    strings.pop + strings.pop,
    strings.pop + strings.pop
  ]
  
end