source: branches/HeuristicLab.Algorithms.IteratedSentenceConstruction/HeuristicLab.Algorithms.IteratedSymbolicExpressionConstruction/3.3/Policies/RandomSymbolicExpressionConstructionPolicy.cs @ 13042

using System;
using System.Collections.Generic;
using System.Linq;
using HeuristicLab.Common;
using HeuristicLab.Core;
using HeuristicLab.Encodings.SymbolicExpressionTreeEncoding;
using HeuristicLab.Persistence.Default.CompositeSerializers.Storable;
using HeuristicLab.Random;

namespace HeuristicLab.Algorithms.IteratedSymbolicExpressionConstruction {
  [StorableClass]
  [Item("RandomSymbolicExpressionConstructionPolicy", "")]
  public class RandomSymbolicExpressionConstructionPolicy : SymbolicExpressionConstructionPolicyBase {

    public RandomSymbolicExpressionConstructionPolicy()
      : base() {
    }

    protected override int Select(IReadOnlyList<object> followStates, IRandom random) {
      var idxs = Enumerable.Range(0, followStates.Count);
      return idxs.SampleRandom(random);
    }

    public sealed override void Update(IEnumerable<object> stateSequence, double quality) {
      // ignore
    }

    protected override object CreateState(ISymbolicExpressionTreeNode root, List<ISymbol> actionSequence, ISymbolicExpressionTreeNode parent, int childIdx) {
      return null; // doesn't use state information
    }

    #region IItem
    protected RandomSymbolicExpressionConstructionPolicy(RandomSymbolicExpressionConstructionPolicy original, Cloner cloner)
      : base(original, cloner) {
    }

    [StorableConstructor]
    protected RandomSymbolicExpressionConstructionPolicy(bool deserializing) : base(deserializing) { }

    public override HeuristicLab.Common.IDeepCloneable Clone(HeuristicLab.Common.Cloner cloner) {
      return new RandomSymbolicExpressionConstructionPolicy(this, cloner);
    }

    #endregion
  }
}