source: branches/HeuristicLab.Problems.GrammaticalOptimization/HeuristicLab.Algorithms.GeneticProgramming/StandardGP.cs @ 12009

using System;
using System.IO;
using System.IO.Compression;
using System.Linq;
using System.Threading;
using HeuristicLab.Algorithms.GrammaticalOptimization;
using HeuristicLab.Common;
using HeuristicLab.Data;
using HeuristicLab.Encodings.SymbolicExpressionTreeEncoding;
using HeuristicLab.Persistence.Default.Xml;
using HeuristicLab.Problems.GrammaticalOptimization;
using HeuristicLab.Selection;

namespace HeuristicLab.Algorithms.GeneticProgramming {
  public class StandardGP : SolverBase, IGPSolver {
    public int PopulationSize { get; set; }
    public double MutationRate { get; set; }
    public int TournamentGroupSize { get; set; }
    public int MaxSolutionSize { get; set; }
    public int MaxSolutionDepth { get; set; }

    private readonly ISymbolicExpressionTreeProblem problem;
    private readonly Random random;
    private readonly bool saveAlg;

    public StandardGP(ISymbolicExpressionTreeProblem problem, Random random, bool saveAlg = false) {
      this.problem = problem;
      this.random = random;
      // default parameter values
      PopulationSize = 1000;
      TournamentGroupSize = 4;
      MutationRate = 0.15;
      MaxSolutionSize = 100;
      MaxSolutionDepth = 17;
      this.saveAlg = saveAlg;
    }

    public override void Run(int maxEvaluations) {
      var hlProblem = new GenericSymbExprProblem(problem);
      var onEvalLocker = new object();
      hlProblem.MaximumSymbolicExpressionTreeLength.Value = MaxSolutionSize;
      hlProblem.MaximumSymbolicExpressionTreeDepth.Value = MaxSolutionDepth;


      using (var wh = new AutoResetEvent(false)) {
        var ga = new GeneticAlgorithm.GeneticAlgorithm();
        ga.Engine = new ParallelEngine.ParallelEngine();
        ga.ExceptionOccurred += (sender, args) => { Console.WriteLine(args.Value.Message); wh.Set(); };
        ga.Stopped += (sender, args) => { wh.Set(); };

        int numEvals = 0;
        hlProblem.Evaluator.SolutionEvaluated += (sentence, quality) => {
          // raise solution evaluated event for each GP solution, don't scale quality to 0..1 
          // need to synchronize in case we are using a parallel engine
          lock (onEvalLocker) {
            OnSolutionEvaluated(sentence, quality);

            // stop when maxEvals has been reached
            if (numEvals++ >= maxEvaluations) {
              ga.Stop();
            }
          }
        };


        ga.Problem = hlProblem;
        //ga.Problem.SolutionCreatorParameter.ActualValue = new FullTreeCreator();
        var mutator = (MultiSymbolicExpressionTreeManipulator)ga.MutatorParameter.ValidValues.Single(op => op.Name == "MultiSymbolicExpressionTreeManipulator");
        foreach (var op in mutator.Operators) {
          if (op.Name == "ChangeNodeTypeManipulation"
            || op.Name == "ReplaceBranchManipulation") mutator.Operators.SetItemCheckedState(op, true);
          else mutator.Operators.SetItemCheckedState(op, false);
        }
        ga.Mutator = mutator;
        ga.Crossover = ga.CrossoverParameter.ValidValues.Single(op => op.Name == "SubtreeSwappingCrossover");
        var selector = (TournamentSelector)ga.SelectorParameter.ValidValues.Single(op => op.Name == "TournamentSelector");
        selector.GroupSizeParameter.Value = new IntValue(TournamentGroupSize);
        ga.Selector = selector;

        ga.PopulationSize.Value = PopulationSize;
        ga.MaximumGenerations.Value = 1000000; // very large value (we stop in the evaluate handler)
        ga.MutationProbability.Value = MutationRate;

        ga.SetSeedRandomly = new BoolValue(false);
        ga.Seed = new IntValue(random.Next());

        ga.Prepare();
        ga.Start();

        wh.WaitOne();


        if (saveAlg) {
          var path = @"C:\Users\P24581\Desktop";
          var fileName = string.Format("osgp-{0}{1:D2}{2:D2}{3:D2}{4:D2}.hl", DateTime.Now.Year, DateTime.Now.Month, DateTime.Now.Day, DateTime.Now.Hour, DateTime.Now.Minute);
          var fullPath = Path.Combine(path, fileName);
          HeuristicLab.Persistence.Core.ConfigurationService.Instance.LoadSettings();
          XmlGenerator.Serialize(ga, fullPath, CompressionLevel.Fastest);
        }
      }
    }
  }
}