109 lines
2.8 KiB
Ruby
109 lines
2.8 KiB
Ruby
# Copyright (C) 2024-2025 LibreWeddingPlanner contributors
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# frozen_string_literal: true
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module VNS
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class Engine
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PERTURBATION_SIZES = [1, 1, 1, 2, 2, 3].freeze
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ITERATIONS = 50
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class << self
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def sequence(elements)
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elements = elements.to_a
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(elements + elements.reverse).chunk(&:itself).map(&:first)
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end
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end
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def target_function(&function)
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@target_function = function
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end
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def add_optimization(klass)
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@optimizations ||= Set.new
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@optimizations << klass
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end
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def add_perturbation(klass)
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@perturbations ||= Set.new
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@perturbations << klass
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end
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def notify_progress(&block)
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@progress_notifier = block
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end
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def on_better_solution(&block)
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@better_solution_notifier = block
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end
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attr_writer :initial_solution
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def run
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raise 'No target function defined' unless @target_function
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raise 'No optimizations defined' unless @optimizations
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raise 'No initial solution defined' unless @initial_solution
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@perturbations ||= Set.new
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@current_solution = @initial_solution
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@best_score = @target_function.call(@current_solution)
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run_all_optimizations
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@progress_notifier&.call(Rational(1, ITERATIONS + 1))
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best_solution = @current_solution
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ITERATIONS.times do |iteration|
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@current_solution = Tables::WheelSwap.new(best_solution).call(PERTURBATION_SIZES.sample)
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@best_score = @target_function.call(@current_solution)
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Rails.logger.debug { "After perturbation: #{@best_score}" }
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run_all_optimizations
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@progress_notifier&.call(Rational(iteration + 1, ITERATIONS + 1))
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next unless best_solution.discomfort > @current_solution.discomfort
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best_solution = @current_solution
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@better_solution_notifier&.call(best_solution)
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Rails.logger.debug do
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"Found better solution after perturbation optimization: #{@current_solution.discomfort}"
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end
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end
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best_solution
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end
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private
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def run_all_optimizations
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self.class.sequence(@optimizations).each do |optimization|
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optimize(optimization)
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Rails.logger.debug { "Finished optimization phase: #{optimization}" }
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end
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Rails.logger.debug { 'Finished all optimization phases' }
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end
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def optimize(optimization_klass)
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loop do
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optimized = false
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optimization_klass.new(@current_solution).each do |alternative_solution|
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score = @target_function.call(alternative_solution)
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next if score >= @best_score
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@current_solution = alternative_solution.deep_dup
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@best_score = score
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optimized = true
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Rails.logger.debug { "[#{optimization_klass}] Found better solution with score: #{score}" }
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break
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end
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return unless optimized
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end
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end
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end
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end
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