Added an example of evolving a constant number with integers 0-9 and …

…addition, subtraction, multiplication, and protected division.

examples/constant.rb

@@ -0,0 +1,26 @@
+require File.join(File.dirname(__FILE__), "..", "revolve")
+
+class Integer
+  def protected_division(divisor)
+    self / divisor rescue 1
+  end
+end
+
+population = Revolve::Population.initialized( 200, {  
+  :program_size => 10,
+  :instructions => [1, 2, 3, 4, 5, 6, 7, 8, 9,
+                    Revolve::Method.new(:+), Revolve::Method.new(:-), 
+                    Revolve::Method.new(:*), Revolve::Method.new(:protected_division)],
+  :max_generations => 500,                    
+  :fitness_cases => [ lambda{|program| program.run.to_i - 120 } ],
+  :fitness_combinator => lambda{|cases| cases.first.abs },
+  :crossover_chance => 0.6,
+  :mutation_chance => 0.3
+})
+
+population.evolve!
+
+puts "Generations: #{population.generation}"
+puts "Fitness: #{population.fitness(population.fittest_program)}"
+puts "Program:\n#{population.fittest_program.inspect}"
+puts "Output: #{population.fittest_program.run}"

lib/method.rb

@@ -16,5 +16,9 @@ def call!
       target.method(name).arity.times { arguments.push(stack.pop) }
       stack.push( target.send(*arguments) ).last
     end
+
+    def inspect
+      "(:#{name} method)"
+    end
   end
 end

lib/population.rb

@@ -23,9 +23,10 @@ def self.initialized(size, parameters)
 
     def evolve!
       update_fittest_program!
-      max_generations.times do        
+      max_generations.times do 
+        break if fitness(fittest_program) == 0       
         evolve_generation!    
-        update_fittest_program!
+        update_fittest_program!        
       end      
       fittest_program
     end

spec/method/inspect_spec.rb

@@ -0,0 +1,13 @@
+require File.join(File.dirname(__FILE__), "..", "spec_helper")
+
+module Revolve
+
+describe Method, "#inspect" do
+  before { @method = Method.new(:+) }
+
+  it "should be the name wrapped in 'method'" do
+    @method.inspect.should == "(:+ method)"
+  end
+end
+
+end