Class: EvoSynth::Evolvers::BalancedCoevolutionary

Inherits:
Object
  • Object
show all
Includes:
Evolver
Defined in:
lib/evosynth/evolvers/coevolutionary/balanced_coevolutionary.rb

Overview

based on “Coevolution, Memory and Balance” from Paredis, 1999

evolves two populations (problems, solutions / predator, prey) in a balanced manner

Constant Summary collapse

DEFAULT_PAIRING_RUNS = 
20
DEFAULT_SELECTION = 
EvoSynth::Selections::FitnessProportionalSelection.new
DEFAULT_RECOMBINATION = 
EvoSynth::Recombinations::KPointCrossover.new(2)
DEFAULT_RECOMBINATION_PROBABILITY = 
0.75

Instance Attribute Summary collapse

Attributes included from RunnableEvolver

#generations_computed

Instance Method Summary collapse

Methods included from ProfileUsingEvolver

#init_profile, #use_profile

Methods included from RunnableEvolver

#run_until, #run_until_fitness_reached, #run_until_generations_reached

Constructor Details

#initialize(profile) ⇒ BalancedCoevolutionary 



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# File 'lib/evosynth/evolvers/coevolutionary/balanced_coevolutionary.rb', line 42

def initialize(profile)
  init_profile :population,
    :problems,
      :evaluator,
    :mutation,
      :problem_mutation,
    :recombination => DEFAULT_RECOMBINATION,
      :problem_recombination => DEFAULT_RECOMBINATION,
    :parent_selection => DEFAULT_SELECTION,
    :enviromental_selection => DEFAULT_SELECTION,
    :pairing_runs => DEFAULT_PAIRING_RUNS

  use_profile profile

  # intialize fitnesses?! FIXME: find a better way to do this
  solution = @parent_selection.select(@population, 1).first
  @problems.each do |problem|
    @evaluator.encounter(problem, solution)
  end

  problem = @parent_selection.select(@problems, 1).first
  @population.each do |solution|
    @evaluator.encounter(problem, solution)
  end
end

Instance Attribute Details

#solution_success ⇒ Object (readonly)

Returns the value of attribute solution_success.



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# File 'lib/evosynth/evolvers/coevolutionary/balanced_coevolutionary.rb', line 35

def solution_success
  @solution_success
end

Instance Method Details

#best_solution ⇒ Object 



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# File 'lib/evosynth/evolvers/coevolutionary/balanced_coevolutionary.rb', line 72

def best_solution
  @population.best
end

#next_generation ⇒ Object 



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# File 'lib/evosynth/evolvers/coevolutionary/balanced_coevolutionary.rb', line 84

def next_generation
  problem_wins, solution_wins = 0, 0

  @pairing_runs.times do
    problem = @parent_selection.select(@problems, 1).first
    solution = @parent_selection.select(@population, 1).first
    winner = @evaluator.encounter(problem, solution)
    winner == problem ? problem_wins += 1 : solution_wins += 1
  end

  @solution_success = solution_wins / @pairing_runs.to_f

  if EvoSynth.rand < @solution_success
    # select, recombine and mutate solution child
    evolve_offspring(@population, @problems, @recombination,
      @mutation) { |child, enemy| @evaluator.encounter(enemy, child, false, true) }
  else
    # select, recombine and mutate problem child
    evolve_offspring(@problems, @population, @problem_recombination,
      @problem_mutation) { |child, enemy| @evaluator.encounter(child, enemy, true, false) }
  end        
end

#return_result ⇒ Object 



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# File 'lib/evosynth/evolvers/coevolutionary/balanced_coevolutionary.rb', line 80

def return_result
  @population
end

#to_s ⇒ Object 



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# File 'lib/evosynth/evolvers/coevolutionary/balanced_coevolutionary.rb', line 68

def to_s
  "C-M-B coevolutionary algorithm <mutation: #{@mutation}, recombination: #{@recombination}, parent selection: #{@parent_selection}, enviromental selection: #{@enviromental_selection}>"
end

#worst_solution ⇒ Object 



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# File 'lib/evosynth/evolvers/coevolutionary/balanced_coevolutionary.rb', line 76

def worst_solution
  @population.worst
end