Class: ReplaceWorstReplaceStrategy

Inherits:
ReplaceStrategy show all
Defined in:
lib/gimuby/genetic/population/replace_strategy/replace_worst_replace_strategy.rb

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize ⇒ ReplaceWorstReplaceStrategy

Returns a new instance of ReplaceWorstReplaceStrategy.



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# File 'lib/gimuby/genetic/population/replace_strategy/replace_worst_replace_strategy.rb', line 5

def initialize
  @replace_proportion = 50.to_f / 100.to_f
end

Instance Attribute Details

#replace_proportion ⇒ Object

Returns the value of attribute replace_proportion.



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# File 'lib/gimuby/genetic/population/replace_strategy/replace_worst_replace_strategy.rb', line 9

def replace_proportion
  @replace_proportion
end

Instance Method Details

#replace(population, selected = nil) ⇒ Object 



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# File 'lib/gimuby/genetic/population/replace_strategy/replace_worst_replace_strategy.rb', line 11

def replace(population, selected = nil)
  solutions = population.solutions.clone

  wished_length = solutions.length
  solutions.sort! do |x, y|
    x_fitness = population.get_fitness(x)
    y_fitness = population.get_fitness(y)
    x_fitness <=> y_fitness
  end
  if selected.nil?
    selected = population.pick
  end
  number_to_remove = (wished_length * @replace_proportion).floor
  if number_to_remove == wished_length
    number_to_remove -= 1
  end
  solutions.slice!(-number_to_remove, number_to_remove)

  while solutions.length < wished_length
    begin
      random_index1 = rand(selected.length)
      random_index2 = rand(selected.length)
    end while ((random_index1 == random_index2) && (selected.length != 1))
    new_solutions = reproduce(selected[random_index1],
                              selected[random_index2])
    new_solutions.each do |new_solution|
      solutions.push(new_solution)
    end
  end

  solutions.slice!(wished_length) # we could have one that should be dropped
  solutions
end