Class: GA::ClassicGenetic

Inherits:
Algorithm show all
Defined in:
lib/genetic_algorithm.rb

Instance Method Summary collapse

Constructor Details

#initialize(factory, options = {}) ⇒ ClassicGenetic

Returns a new instance of ClassicGenetic.



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# File 'lib/genetic_algorithm.rb', line 26

def initialize(factory, options={})
    super
end

Instance Method Details

#maximize(iterations, options = {}, &fitness) ⇒ Object 



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# File 'lib/genetic_algorithm.rb', line 30

def maximize(iterations, options = {}, &fitness)
    optimize(iterations, options, &fitness)
end

#minimize(iterations, options = {}, &fitness) ⇒ Object 



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# File 'lib/genetic_algorithm.rb', line 34

def minimize(iterations, options = {}, &fitness)
    optimize(iterations, options) { |chromosome| -fitness.call(chromosome) }
end

#optimize(iterations, options = {}, &fitness) ⇒ Object 



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# File 'lib/genetic_algorithm.rb', line 38

def optimize(iterations, options = {}, &fitness)
    GA.contract("You must pass the fitness function as a block") { fitness }
    optimum = options[:optimum] || nil
    
    GA.contract("Iterations must be more than 0") { iterations & iterations > 0 }
    GA.contract("Optimum must be numeric (or nil)") { !optimum || optimum.is_a?(Numeric) }
    
    population = @factory.population(@population_size)
    
    elite = []
    iterations.times do |i|
        GA::Logger.info "Generation #{i}"
        population.each { |chromosome| chromosome.fitness = fitness.call(chromosome) }
        
        population = population - population.min(elite.size) { |chromosome| chromosome.fitness } + elite 
        
        elite = population.max(@elite * @population_size) { |chromosome| chromosome.fitness }
        if optimum
            return elite[0] if elite[0].fitness == optimum
        end

        population = @selection.apply(population)
        population = @crossover.apply(population)                
        population =  @mutation.apply(population)
        
        # Uses additional operators
        @operators.each do |operator|
            population = operator.apply(population)
        end
        
        GA::Logger.info { "Average fitness: #{population.map { |c| c.fitness }.sum.to_f / population.size}" }
    end
    
    return population.max { |chromosome| fitness.call(chromosome) }
end