add GreatDeluge

examples/tsp.rb

@@ -8,6 +8,7 @@
 require 'alns'
 require 'alns/state'
 require 'alns/accept/hill_climbing'
+require 'alns/accept/great_deluge'
 require 'alns/select/roulette_wheel'
 require 'alns/stop/max_iterations'
 require 'alns/stop/max_runtime'
@@ -81,6 +82,7 @@ def self.solve
 
     select = ALNS::Select::RouletteWheel.new([3, 2, 1, 0.5], 0.8, num_destroy, num_repair)
     accept = ALNS::Accept::HillClimbing.new
+    # accept = ALNS::Accept::GreatDeluge.new(1.05, 0.01)
     stop = ALNS::Stop::MaxIterations.new(max_iterations)
     # stop = ALNS::Stop::MaxRuntime.new(2)
 

lib/alns/accept/great_deluge.rb

@@ -0,0 +1,29 @@
+# frozen_string_literal: true
+
+require 'alns/accept/base'
+
+module ALNS
+  module Accept
+    class GreatDeluge < Base
+      def initialize(alpha, beta)
+        if alpha <= 1 || !(0 < beta && beta < 1)
+          raise ArgumentError, 'alpha must be > 1 and beta must be in (0, 1).'
+        end
+
+        @alpha = alpha
+        @beta = beta
+        @threshold = nil
+      end
+
+      def accept?(_rnd, best, _current, candidate)
+        @threshold = @alpha * best.objective if @threshold.nil?
+
+        diff = @threshold - candidate.objective
+
+        @threshold -= @beta * diff
+
+        diff.positive?
+      end
+    end
+  end
+end

lib/alns/accept/threshold.rb

@@ -0,0 +1,28 @@
+# frozen_string_literal: true
+
+module ALNS
+  module Accept
+    module Threshold
+      LINEAR = 1
+      EXPONENTIAL = 2
+
+      def self.to_s(value)
+        case value
+        when LINEAR then 'LINEAR'
+        when EXPONENTIAL then 'EXPONENTIAL'
+        else
+          raise ArgumentError, "Invalid method: #{value}"
+        end
+      end
+
+      def self.update(current, step, method)
+        case method
+        when LINEAR then current - step
+        when EXPONENTIAL then current * step
+        else
+          raise ArgumentError, "Invalid method: #{value}"
+        end
+      end
+    end
+  end
+end

test/accept/great_deluge_test.rb

@@ -0,0 +1,18 @@
+# frozen_string_literal: true
+
+require_relative '../test_helper'
+require 'minitest/autorun'
+require 'alns/accept/great_deluge'
+require_relative '../fake_state'
+
+class GreatDelugeTest < Minitest::Test
+  def test_accept?
+    accept = ALNS::Accept::GreatDeluge.new(2, 0.01)
+
+    assert !accept.accept?(nil, Zero, Zero, One)
+
+    assert accept.accept?(nil, Zero, Zero, Zero)
+
+    assert accept.accept?(nil, Zero, Zero, Zero)
+  end
+end

test/accept/hill_climbing_test.rb

@@ -3,7 +3,7 @@
 require_relative '../test_helper'
 require 'minitest/autorun'
 require 'alns/accept/hill_climbing'
-require_relative '../models'
+require_relative '../fake_state'
 
 class HillClimbingTest < Minitest::Test
   def test_accept?

test/models.rb → test/fake_state.rb

@@ -1,6 +1,5 @@
 # frozen_string_literal: true
 
-require 'minitest/autorun'
 require 'alns/state'
 
 class FakeState < ALNS::State
@@ -11,3 +10,8 @@ def initialize(val)
     @objective = val
   end
 end
+
+Sentinel = FakeState.new(0)
+Zero = FakeState.new(0)
+One = FakeState.new(1)
+Two = FakeState.new(2)

test/select/roulette_wheel_test.rb

@@ -3,7 +3,7 @@
 require_relative '../test_helper'
 require 'minitest/autorun'
 require 'alns/select/roulette_wheel'
-require_relative '../models'
+require_relative '../fake_state'
 
 class RouletteWheelTest < Minitest::Test
   def setup

test/solver_test.rb

@@ -6,7 +6,7 @@
 require 'alns/accept/hill_climbing'
 require 'alns/select/roulette_wheel'
 require 'alns/stop/max_iterations'
-require_relative 'models'
+require_relative 'fake_state'
 
 class SolverTest < Minitest::Test
   def setup

test/stop/no_improvement_test.rb

@@ -1,7 +1,7 @@
 # frozen_string_literal: true
 
 require_relative '../test_helper'
-require_relative '../models'
+require_relative '../fake_state'
 require 'minitest/autorun'
 require 'alns/stop/no_improvement'