Class: Population

Inherits:
Object
  • Object
show all
Defined in:
lib/charlie/population.rb

Overview

The population class represents an array of genotypes. Create an instance of this, and call one of the evolve functions to run the genetic algorithm.

Constant Summary collapse

DEFAULT_MAX_GENS = 
100

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(genotype_class, population_size = 20) ⇒ Population

Returns a new instance of Population.



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# File 'lib/charlie/population.rb', line 10

def initialize(genotype_class,population_size=20)
  @size = population_size
  @genotype_class = genotype_class
  @population = Array.new(population_size){ genotype_class.new } 
end

Instance Attribute Details

#genotype_class ⇒ Object (readonly)

Returns the value of attribute genotype_class.



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# File 'lib/charlie/population.rb', line 9

def genotype_class
  @genotype_class
end

#population ⇒ Object (readonly)

Returns the value of attribute population.



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# File 'lib/charlie/population.rb', line 9

def population
  @population
end

#size ⇒ Object (readonly)

Returns the value of attribute size.



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# File 'lib/charlie/population.rb', line 9

def size
  @size
end

Instance Method Details

#evolve_block(max_generations = DEFAULT_MAX_GENS) {|@population, 0| ... } ⇒ Object

yields population and generation number to block each generation, for a maximum of max_generations.

Yields:



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# File 'lib/charlie/population.rb', line 17

def evolve_block(max_generations=DEFAULT_MAX_GENS)
  yield @population, 0
  (max_generations || DEFAULT_MAX_GENS).times {|generation|
    @population = @genotype_class.next_generation(@population){|*parents|
      ch = [*@genotype_class.cross(*parents)]
      ch.each{|c| c.mutate! }
      ch
    }
    yield @population, generation+1
  }
  @population
end

#evolve_on_console(generations = DEFAULT_MAX_GENS) ⇒ Object Also known as: evolve

Runs the genetic algorithm with some stats on the console. Returns the population sorted by fitness.



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# File 'lib/charlie/population.rb', line 37

def evolve_on_console(generations=DEFAULT_MAX_GENS)
  puts "Generation\tBest Fitness\t\tBest Individual"
  evolve_block(generations) {|p,g|
    best = p.max
    puts "#{g}\t\t#{best.fitness}\t\t#{best.to_s}"
  }
  @population = @population.sort_by{|x|x.fitness}
  puts "Finished: Best fitness = #{@population[-1].fitness}"
  @population
end

#evolve_silent(generations = DEFAULT_MAX_GENS) ⇒ Object

Runs the genetic algorithm without any output. Returns the population sorted by fitness (unsorted for co-evolution).



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# File 'lib/charlie/population.rb', line 31

def evolve_silent(generations=DEFAULT_MAX_GENS)
  evolve_block(generations){}
  @population.sort_by{|x|x.fitness} rescue @population
end

#evolve_until_best(generations = DEFAULT_MAX_GENS, check_every = 10) ⇒ Object Also known as: evolve_until

breaks if the block (which is passed the best individual each “check_every” generations) returns true. returns an array [population, generations needed]. generations needed==nil for no convergence.



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# File 'lib/charlie/population.rb', line 64

def evolve_until_best(generations=DEFAULT_MAX_GENS,check_every=10)
  tot_gens = nil
  evolve_block(generations)  {|p,g|
    if (g % check_every).zero? && yield(p.max)
      tot_gens = g
      break 
    end
  }
  [@population, tot_gens]
end

#evolve_until_population(generations = DEFAULT_MAX_GENS, check_every = 10) ⇒ Object

breaks if the block (which is passed the population each “check_every” generations) returns true. returns an array [population, generations needed]. generations needed==nil for no convergence.



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# File 'lib/charlie/population.rb', line 51

def evolve_until_population(generations=DEFAULT_MAX_GENS,check_every=10)
  tot_gens = nil
  evolve_block(generations) {|p,g|
    if (g % check_every).zero? && yield(p)
      tot_gens = g
      break
    end
  }
  [@population, tot_gens]
end