Generic genetic optimizer + tests

Author: Eric Matte

.rubocop.yml

@@ -10,6 +10,9 @@ Metrics/LineLength:
 Metrics/MethodLength:
   Max: 35
 
+Metrics/ClassLength:
+  Enabled: false
+
 Gemspec/OrderedDependencies:
   Enabled: false
 

.vscode/settings.json

@@ -1,5 +1,6 @@
 {
-  "editor.formatOnSave": false,
+  "editor.formatOnSave": true,
+  "editor.formatOnSaveTimeout": 5000,
   "editor.tabSize": 2,
   "files.trimTrailingWhitespace": true,
   "files.insertFinalNewline": true,

Gemfile

@@ -3,3 +3,4 @@ source "https://rubygems.org"
 # Specify your gem's dependencies in genetic-algorithm-resolver.gemspec
 gemspec
 
+gem "rubocop"

Gemfile.lock

@@ -6,13 +6,30 @@ PATH
 GEM
   remote: https://rubygems.org/
   specs:
+    ast (2.4.0)
     debase (0.2.4.1)
       debase-ruby_core_source (>= 0.10.2)
     debase-ruby_core_source (0.10.6)
+    jaro_winkler (1.5.2)
     minitest (5.11.3)
+    parallel (1.13.0)
+    parser (2.6.2.0)
+      ast (~> 2.4.0)
+    psych (3.1.0)
+    rainbow (3.0.0)
     rake (12.3.3)
+    rubocop (0.66.0)
+      jaro_winkler (~> 1.5.1)
+      parallel (~> 1.10)
+      parser (>= 2.5, != 2.5.1.1)
+      psych (>= 3.1.0)
+      rainbow (>= 2.2.2, < 4.0)
+      ruby-progressbar (~> 1.7)
+      unicode-display_width (>= 1.4.0, < 1.6)
     ruby-debug-ide (0.7.0)
       rake (>= 0.8.1)
+    ruby-progressbar (1.10.0)
+    unicode-display_width (1.5.0)
 
 PLATFORMS
   ruby
@@ -23,6 +40,7 @@ DEPENDENCIES
   genetic-algorithm-resolver!
   minitest (~> 5.0)
   rake (~> 12.3.2)
+  rubocop
   ruby-debug-ide (~> 0.7)
 
 BUNDLED WITH

lib/genetic/algorithm/chromosome.rb

@@ -1,21 +1,21 @@
-# A member of a given population
-class Genetic::Algorithm::Chromosome
-  attr_accessor :genes
-  attr_accessor :fitness
+module Genetic
+  module Algorithm
+    # A member of a given population
+    class Chromosome
+      attr_reader :genes
+      attr_reader :fitness
 
-  def initialize(genes:, fitness:)
-    @genes = genes
-    @fitness = fitness
-  end
+      def initialize(genes, fitness_calculator)
+        @genes = genes
+        @fitness = fitness_calculator.call(genes)
+      end
 
-  # Randomly change one of its gene.
-  # Help maintain diversity within the population and prevent premature convergence.
-  # @param [(Object | Float)[][]] ranges - The available ranges to mutate from for all genes. ranges.lenght must equals genes.length
-  # @param [Boolean] sampleFromRanges
-  #                  If true:  take one of the available values for a given range
-  #                  if false: take a random floating value between ranges[i][0] and ranges[i][1]
-  def mutate(ranges, sample_from_ranges = false)
-    i = rand(0..(genes.length - 1))
-    @genes[i] = sample_from_ranges ? ranges[i].sample : rand(ranges[i][0]..ranges[i][1])
+      # Randomly change one of its gene.
+      # Help maintain diversity within the population and prevent premature convergence.
+      def mutate(genes_generator)
+        i = rand(0..(genes.length - 1))
+        @genes[i] = genes_generator.call(i)
+      end
+    end
   end
 end

lib/genetic/algorithm/fitness_recorder.rb

@@ -1,9 +1,10 @@
 # Record and display best individuals accross generations
 class Genetic::Algorithm::FitnessRecorder
-  attr_accessor :best_individual
+  attr_reader :best_individual
 
   def initialize
     @best_individual = nil
+    @best_individual_generation = nil
     @max_fitness = []
     @max_overall_finess = []
     @average_fitness = []
@@ -12,12 +13,13 @@ def initialize
   def record_generation(generation, population)
     best_generation_individual = population.max_by(&:fitness)
 
-    # Save best individual across all generations
-    if best_generation_individual.fitness > (@best_individual&.fitness || -1e10)
+    # Save the best individual across all generations
+    if best_generation_individual.fitness > @best_individual&.fitness
       @best_individual = best_generation_individual
+      @best_individual_generation = generation
     end
 
-    # Record progress information
+    # Record progress information across all generations
     @max_fitness << best_generation_individual.fitness
     @max_overall_finess << @best_individual.fitness
     average = population.map(&:fitness).inject(:+) / population.length
@@ -29,18 +31,17 @@ def record_generation(generation, population)
     puts "    Average population fitness: #{average}"
   end
 
-  def display_best_individual(shifts)
+  def display_best_individual
     puts "\n"
-    puts "Result: Best overall individual fitness: #{@best_individual.fitness}"
-    puts "                                                     Shift\t->\tSelected employee:"
-    print_shift = ->(shift) { "[#{shift.start_at.localtime} - #{shift.end_at.localtime}]: #{shift.position.name}" }
-    print_employee = ->(employee) { "#{employee.profile.full_name} (#{employee.email})" }
-    puts shifts.each_with_index.map { |s, i| "#{print_shift[s[:shift]]}\t->\t#{print_employee[@best_individual.genes[i].user]}" }
-
-    # puts "#{@max_fitness.each_with_index.map { |_, i| i }},"
-    # puts "#{@max_fitness},"
-    # puts "#{@max_overall_finess},"
-    # puts "#{@average_fitness},"
+    puts "Result: The best overall individual was found on generation #{@best_individual_generation} with:"
+    puts "    Fitness: #{@best_individual.fitness}"
+    puts "    Genes: #{@best_individual.fitness}"
+    puts "\n---\n"
+    puts "Generations evlotion:"
+    puts "#{@max_fitness.each_with_index.map { |_, i| i }},"
+    puts "#{@max_fitness},"
+    puts "#{@max_overall_finess},"
+    puts "#{@average_fitness},"
   end
 
   def save_best_individual_genes

lib/genetic/algorithm/optimiser.rb

@@ -0,0 +1,76 @@
+module Genetic
+  module Algorithm
+    class Optimiser
+      attr_accessor :crossover_probability # Int
+      attr_accessor :mutation_probability  # Int
+      attr_accessor :population_size       # Int
+      attr_accessor :number_of_generations # Int
+      attr_accessor :genes_generator       # (index: Int?) -> Array<Gene> | Gene if index.nil?
+      attr_accessor :fitness_calculator    # (genes: Array<Gene>) -> Int
+
+      def execute
+        population = initialize_population
+
+        fitness_recorder = FitnessRecorder.new
+        @number_of_generations.times.each do |generation|
+          if generation != @number_of_generations
+            population = do_natural_selection(population)
+          end
+          fitness_recorder.record_generation(generation, population)
+        end
+
+        fitness_recorder.display_best_individual
+      end
+
+      private
+
+      def initialize_population
+        population = []
+        @population_size.times.each do
+          population << Chromosome.new(@genes_generator.call, @fitness_calculator)
+        end
+        population
+      end
+
+      def do_natural_selection(population)
+        total_fitness = population.map(&:fitness).inject(:+)
+        new_population = []
+        (@population_size / 2).times.each do
+          parent1 = weighted_random_sampling(population, total_fitness)
+          parent2 = weighted_random_sampling(population - [parent1], total_fitness)
+
+          child1, child2 = mate(parent1, parent2)
+
+          new_population << child1
+          new_population << child2
+        end
+
+        new_population
+      end
+
+      def weighted_random_sampling(population, total_fitness)
+        population.max_by { |chromosome| rand**(total_fitness / chromosome.fitness) }
+      end
+
+      def mate(parent1, parent2)
+        # crossover
+        if rand < @crossover_probability
+          i = rand(1..parent1.genes.length - 1)
+          child1 = Chromosome.new(parent1.genes[0..i - 1] + parent2.genes[i..-1], @fitness_calculator)
+          child2 = Chromosome.new(parent2.genes[0..i - 1] + parent1.genes[i..-1], @fitness_calculator)
+        else
+          child1 = Chromosome.new(parent1.genes.dup, @fitness_calculator)
+          child2 = Chromosome.new(parent2.genes.dup, @fitness_calculator)
+        end
+
+        # mutation
+        if rand < @mutation_probability
+          child1.mutate(@genes_generator)
+          child2.mutate(@genes_generator)
+        end
+
+        [child1, child2]
+      end
+    end
+  end
+end

test/genetic/algorithm/chromosome_test.rb

@@ -2,48 +2,31 @@
 require "genetic/algorithm/chromosome"
 
 class Genetic::Algorithm::ChromosomeTest < Minitest::Test
-  def test_it_can_mutate_floats
-    20.times do
-      test_genes = Array.new(rand(1..20)) { rand(0..100) }
-      test_ranges = Array.new(test_genes.length) do |i|
-        el = test_genes[i].to_f
-        [rand(el - 50.0..el), rand(el..el + 50.0)]
-      end
-
-      chromosome = Genetic::Algorithm::Chromosome.new(fitness: nil, genes: test_genes.dup)
-      chromosome.mutate(test_ranges)
-
-      number_of_mutated_genes = 0
-      chromosome.genes.each_with_index do |el, i|
-        if el != test_genes[i]
-          number_of_mutated_genes += 1
-        end
-
-        assert(test_ranges[i][0] < el && el < test_ranges[i][1])
-      end
-      assert_equal(1, number_of_mutated_genes)
-    end
-  end
-
   def test_it_can_mutate_with_data_range
     test_ranges = [%w[male female], [18, 19, 20, 21, 22], ["🔥", "❄️", "🌎", "💨"]]
-    test_genes = Array.new(test_ranges.length) { |i| test_ranges[i][0] }
+    genes_generator = proc do |index = nil|
+      index.nil? ? Array.new(test_ranges.length) { |i| test_ranges[i][0] } : test_ranges[index].sample
+    end
+    test_genes = genes_generator.call
 
-    chromosome = Genetic::Algorithm::Chromosome.new(fitness: nil, genes: test_genes.dup)
+    chromosome = Genetic::Algorithm::Chromosome.new(test_genes.dup, method(:fitness_calculator))
     20.times do |i| # Discrete mutations can sometimes return the same value
       assert(false, "Unable to mutate") if i == 20
-      chromosome.mutate(test_ranges, true)
+      chromosome.mutate(genes_generator)
       break if chromosome.genes != test_genes
     end
 
     number_of_mutated_genes = 0
     chromosome.genes.each_with_index do |el, i|
-      if el != test_genes[i]
-        number_of_mutated_genes += 1
-      end
-
-      assert((test_ranges[i].include? el))
+      number_of_mutated_genes += 1 if el != test_genes[i]
+      assert(test_ranges[i].include?(el))
     end
     assert_equal(1, number_of_mutated_genes)
   end
+
+  private
+
+  def fitness_calculator(_genes)
+    1
+  end
 end