Class: Wallace::Operators::OrderCrossoverOperator

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

Overview

The order crossover operator takes two parents as input and creates two offspring.

Two random crossover points on the chromosome (the same for each parent) are selected and the genes at all loci in between are carried to each child (i.e. P0 -> C0, P1 -> C1).

The remaining genes of each child are determined by inserting all genes that are not covered within their central subsequence (copied from the parent) in the order that they appear in the other parent. Once the order of genes has been calculated, the genes are inserted after the second crossover point and are wrapped around the start and to the first crossover point.

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 



14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
 
# File 'lib/operators/order_crossover_operation.rb', line 14

def operate(rng, inputs)

  # Select two random crossover points.
  # All genes between these points are left untouched.
  len = inputs[0].length
  i, j = Array.new(2) { rng.rand(len - 1) }.sort

  # Find the alleles that are not within the selected subsequence of each
  # parent in the order of the other parents chromosome.
  insert = Array.new(2) do |input|
    inputs[(input+1)%2].select { |g| inputs[input][i..j].exclude? g }
  end

  # Inject the alleles in the gathered order starting at the second
  # crossover point before wrapping around to the first.
  (0..1).each do |input|
    inputs[input][j+1...len] = insert[input].shift(len-j-1)
    inputs[input][0...i] = insert[input]
  end

  return inputs

end