Class: EvoSynth::Evolvers::MemeticAlgorithm

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

Overview

MEMETISCHER-ALGORITHMUS (Weicker Page 165) see also: en.wikipedia.org/wiki/Memetic_algorithm for later improvments

Constant Summary collapse

DEFAULT_CHILD_FACTOR = 
0.5
DEFAULT_RECOMBINATION_PROBABILITY = 
1.0
DEFAULT_RECOMBINATION = 
EvoSynth::Recombinations::KPointCrossover.new(2)
DEFAULT_INDIVIDUAL_LEARNING_GOAL = 
->(gen, best) { gen >= 10 }
DEFAULT_INDIVIDUAL_LEARNING_PROBABILITY = 
0.75
DEFAULT_SELECTION = 
EvoSynth::Selections::FitnessProportionalSelection.new
DEFAULT_SUBEVOLVER_CREATOR = 
->(profile) { EvoSynth::Evolvers::LocalSearch.new(profile) }

Instance Attribute Summary

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) ⇒ MemeticAlgorithm

Returns a new instance of MemeticAlgorithm.



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# File 'lib/evosynth/evolvers/basic/memetic_algorithm.rb', line 42

def initialize(profile)
	init_profile :population,
		:evaluator,
	    :mutation,
		:recombination						=> DEFAULT_RECOMBINATION,
		:parent_selection					=> DEFAULT_SELECTION,
		:enviromental_selection				=> DEFAULT_SELECTION,
		:child_factor						=> DEFAULT_CHILD_FACTOR,
		:recombination_probability			=> DEFAULT_RECOMBINATION_PROBABILITY,
	    :subevolver_creator					=> DEFAULT_SUBEVOLVER_CREATOR,
		:individual_learning_goal			=> DEFAULT_INDIVIDUAL_LEARNING_GOAL,
		:individual_learning_probability	=> DEFAULT_INDIVIDUAL_LEARNING_PROBABILITY

	use_profile profile

	@population.each { |individual| @evaluator.calculate_and_set_initial_fitness(individual) }
end

Instance Method Details

#best_solution ⇒ Object 



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# File 'lib/evosynth/evolvers/basic/memetic_algorithm.rb', line 64

def best_solution
	@population.best
end

#next_generation ⇒ Object 



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# File 'lib/evosynth/evolvers/basic/memetic_algorithm.rb', line 76

def next_generation
	selected_population = @parent_selection.select(@population, @population.size * @child_factor)
	child_population = EvoSynth::Population.new

	selected_population.each_index do |index_one|
		index_two = (index_one + 1) % selected_population.size

		if EvoSynth.rand < @recombination_probability
			child_one, child_two = @recombination.recombine(selected_population[index_one], selected_population[index_two])
		else
			child_one = selected_population[index_one]
			child_two = selected_population[index_two]
		end

		child_population.add(@mutation.mutate(child_one))
		child_population.add(@mutation.mutate(child_two))
	end

	child_population.map! do |child|
		if EvoSynth.rand < @individual_learning_probability
			@profile.individual = child
			subevolver = @subevolver_creator.call(@profile)
			subevolver.run_until &@individual_learning_goal
		else
			child
		end
	end

	child_population.each { |individual| @evaluator.calculate_and_set_fitness(individual) }
	@population = @enviromental_selection.select(child_population, @population.size)
end

#return_result ⇒ Object 



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# File 'lib/evosynth/evolvers/basic/memetic_algorithm.rb', line 72

def return_result
	@population
end

#to_s ⇒ Object 



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# File 'lib/evosynth/evolvers/basic/memetic_algorithm.rb', line 60

def to_s
	"memetic algoritm"
end

#worst_solution ⇒ Object 



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# File 'lib/evosynth/evolvers/basic/memetic_algorithm.rb', line 68

def worst_solution
	@population.worst
end