#region License Information /* HeuristicLab * Copyright (C) 2002-2012 Heuristic and Evolutionary Algorithms Laboratory (HEAL) * * This file is part of HeuristicLab. * * HeuristicLab is free software: you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation, either version 3 of the License, or * (at your option) any later version. * * HeuristicLab is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with HeuristicLab. If not, see . */ #endregion using System; using System.Linq; using HeuristicLab.Common; using HeuristicLab.Core; using HeuristicLab.Data; using HeuristicLab.Parameters; using HeuristicLab.Persistence.Default.CompositeSerializers.Storable; using HeuristicLab.PluginInfrastructure; namespace HeuristicLab.Encodings.SymbolicExpressionTreeEncoding { [NonDiscoverableType] [StorableClass] [Item("FullTreeCreator", "An operator that creates new symbolic expression trees using the 'Full' method")] public class FullTreeCreator : SymbolicExpressionTreeCreator, ISymbolicExpressionTreeSizeConstraintOperator, ISymbolicExpressionTreeGrammarBasedOperator { private const string MaximumSymbolicExpressionTreeLengthParameterName = "MaximumSymbolicExpressionTreeLength"; private const string MaximumSymbolicExpressionTreeDepthParameterName = "MaximumSymbolicExpressionTreeDepth"; private const string SymbolicExpressionTreeGrammarParameterName = "SymbolicExpressionTreeGrammar"; private const string ClonedSymbolicExpressionTreeGrammarParameterName = "ClonedSymbolicExpressionTreeGrammar"; #region Parameter Properties public IValueLookupParameter MaximumSymbolicExpressionTreeLengthParameter { get { return (IValueLookupParameter)Parameters[MaximumSymbolicExpressionTreeLengthParameterName]; } } public IValueLookupParameter MaximumSymbolicExpressionTreeDepthParameter { get { return (IValueLookupParameter)Parameters[MaximumSymbolicExpressionTreeDepthParameterName]; } } public IValueLookupParameter SymbolicExpressionTreeGrammarParameter { get { return (IValueLookupParameter)Parameters[SymbolicExpressionTreeGrammarParameterName]; } } public ILookupParameter ClonedSymbolicExpressionTreeGrammarParameter { get { return (ILookupParameter)Parameters[ClonedSymbolicExpressionTreeGrammarParameterName]; } } #endregion #region Properties public IntValue MaximumSymbolicExpressionTreeDepth { get { return MaximumSymbolicExpressionTreeDepthParameter.ActualValue; } } public IntValue MaximumSymbolicExpressionTreeLength { get { return MaximumSymbolicExpressionTreeLengthParameter.ActualValue; } } public ISymbolicExpressionGrammar ClonedSymbolicExpressionTreeGrammar { get { return ClonedSymbolicExpressionTreeGrammarParameter.ActualValue; } } #endregion [StorableConstructor] protected FullTreeCreator(bool deserializing) : base(deserializing) { } protected FullTreeCreator(FullTreeCreator original, Cloner cloner) : base(original, cloner) { } public FullTreeCreator() : base() { Parameters.Add(new ValueLookupParameter(MaximumSymbolicExpressionTreeLengthParameterName, "The maximal length (number of nodes) of the symbolic expression tree (this parameter is ignored).")); Parameters.Add(new ValueLookupParameter(MaximumSymbolicExpressionTreeDepthParameterName, "The maximal depth of the symbolic expression tree (a tree with one node has depth = 0).")); Parameters.Add(new ValueLookupParameter(SymbolicExpressionTreeGrammarParameterName, "The tree grammar that defines the correct syntax of symbolic expression trees that should be created.")); Parameters.Add(new LookupParameter(ClonedSymbolicExpressionTreeGrammarParameterName, "An immutable clone of the concrete grammar that is actually used to create and manipulate trees.")); } public override IDeepCloneable Clone(Cloner cloner) { return new FullTreeCreator(this, cloner); } public override IOperation Apply() { if (ClonedSymbolicExpressionTreeGrammarParameter.ActualValue == null) { SymbolicExpressionTreeGrammarParameter.ActualValue.ReadOnly = true; IScope globalScope = ExecutionContext.Scope; while (globalScope.Parent != null) globalScope = globalScope.Parent; globalScope.Variables.Add(new Variable(ClonedSymbolicExpressionTreeGrammarParameterName, (ISymbolicExpressionGrammar)SymbolicExpressionTreeGrammarParameter.ActualValue.Clone())); } return base.Apply(); } protected override ISymbolicExpressionTree Create(IRandom random) { return Create(random, ClonedSymbolicExpressionTreeGrammar, MaximumSymbolicExpressionTreeLength.Value, MaximumSymbolicExpressionTreeDepth.Value); } public override ISymbolicExpressionTree CreateTree(IRandom random, ISymbolicExpressionGrammar grammar, int maxTreeLength, int maxTreeDepth) { return Create(random, grammar, maxTreeLength, maxTreeDepth); } /// /// Create a symbolic expression tree using the 'Full' method. /// Function symbols are used for all nodes situated on a level above the maximum tree depth. /// Nodes on the last tree level will have Terminal symbols. /// /// Random generator /// Available tree grammar /// Maximum tree depth /// Maximum tree length. This parameter is not used. /// public static ISymbolicExpressionTree Create(IRandom random, ISymbolicExpressionGrammar grammar, int maxTreeLength, int maxTreeDepth) { var tree = new SymbolicExpressionTree(); var rootNode = (SymbolicExpressionTreeTopLevelNode)grammar.ProgramRootSymbol.CreateTreeNode(); if (rootNode.HasLocalParameters) rootNode.ResetLocalParameters(random); rootNode.SetGrammar(new SymbolicExpressionTreeGrammar(grammar)); var startNode = (SymbolicExpressionTreeTopLevelNode)grammar.StartSymbol.CreateTreeNode(); if (startNode.HasLocalParameters) startNode.ResetLocalParameters(random); startNode.SetGrammar(new SymbolicExpressionTreeGrammar(grammar)); rootNode.AddSubtree(startNode); Create(random, startNode, maxTreeDepth - 2); tree.Root = rootNode; return tree; } public static void Create(IRandom random, ISymbolicExpressionTreeNode seedNode, int maxDepth) { // make sure it is possible to create a trees smaller than maxDepth if (seedNode.Grammar.GetMinimumExpressionDepth(seedNode.Symbol) > maxDepth) throw new ArgumentException("Cannot create trees of depth " + maxDepth + " or smaller because of grammar constraints.", "maxDepth"); int arity = seedNode.Grammar.GetMaximumSubtreeCount(seedNode.Symbol); // Throw an exception if the seedNode happens to be a terminal, since in this case we cannot grow a tree. if (arity <= 0) throw new ArgumentException("Cannot grow tree. Seed node shouldn't have arity zero."); var allowedSymbols = seedNode.Grammar.AllowedSymbols .Where(s => s.InitialFrequency > 0.0 && seedNode.Grammar.GetMaximumSubtreeCount(s) > 0) .ToList(); for (var i = 0; i < arity; i++) { var possibleSymbols = allowedSymbols .Where(s => seedNode.Grammar.IsAllowedChildSymbol(seedNode.Symbol, s, i)) .ToList(); var selectedSymbol = possibleSymbols.SelectRandom(random); var tree = selectedSymbol.CreateTreeNode(); if (tree.HasLocalParameters) tree.ResetLocalParameters(random); seedNode.AddSubtree(tree); } // Only iterate over the non-terminal nodes (those which have arity > 0) // Start from depth 2 since the first two levels are formed by the rootNode and the seedNode foreach (var subTree in seedNode.Subtrees) if (subTree.Grammar.GetMaximumSubtreeCount(subTree.Symbol) > 0) RecursiveCreate(random, subTree, 2, maxDepth); } private static void RecursiveCreate(IRandom random, ISymbolicExpressionTreeNode root, int currentDepth, int maxDepth) { var arity = root.Grammar.GetMaximumSubtreeCount(root.Symbol); // In the 'Full' grow method, we cannot have terminals on the intermediate tree levels. if (arity <= 0) throw new ArgumentException("Cannot grow node of arity zero. Expected a function node."); var allowedSymbols = root.Grammar.AllowedSymbols .Where(s => s.InitialFrequency > 0.0) .ToList(); for (var i = 0; i < arity; i++) { var possibleSymbols = allowedSymbols .Where(s => root.Grammar.IsAllowedChildSymbol(root.Symbol, s, i) && root.Grammar.GetMinimumExpressionDepth(s) - 1 <= maxDepth - currentDepth && root.Grammar.GetMaximumExpressionDepth(s) > maxDepth - currentDepth) .ToList(); if (!possibleSymbols.Any()) throw new InvalidOperationException("No symbols are available for the tree."); var selectedSymbol = possibleSymbols.SelectRandom(random); var tree = selectedSymbol.CreateTreeNode(); if (tree.HasLocalParameters) tree.ResetLocalParameters(random); root.AddSubtree(tree); } foreach (var subTree in root.Subtrees) if (subTree.Grammar.GetMaximumSubtreeCount(subTree.Symbol) > 0) RecursiveCreate(random, subTree, currentDepth + 1, maxDepth); } } }