[645] | 1 | #region License Information
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| 2 | /* HeuristicLab
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[9456] | 3 | * Copyright (C) 2002-2013 Heuristic and Evolutionary Algorithms Laboratory (HEAL)
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[645] | 4 | *
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| 5 | * This file is part of HeuristicLab.
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| 6 | *
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| 7 | * HeuristicLab is free software: you can redistribute it and/or modify
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| 8 | * it under the terms of the GNU General Public License as published by
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| 9 | * the Free Software Foundation, either version 3 of the License, or
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| 10 | * (at your option) any later version.
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| 11 | *
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| 12 | * HeuristicLab is distributed in the hope that it will be useful,
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| 13 | * but WITHOUT ANY WARRANTY; without even the implied warranty of
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| 14 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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| 15 | * GNU General Public License for more details.
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| 16 | *
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| 17 | * You should have received a copy of the GNU General Public License
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| 18 | * along with HeuristicLab. If not, see <http://www.gnu.org/licenses/>.
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| 19 | */
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| 20 | #endregion
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| 21 |
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| 22 | using System.Linq;
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[4722] | 23 | using HeuristicLab.Common;
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[645] | 24 | using HeuristicLab.Core;
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[3512] | 25 | using HeuristicLab.Persistence.Default.CompositeSerializers.Storable;
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[7662] | 26 | using System.Collections.Generic;
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[645] | 27 |
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[5499] | 28 | namespace HeuristicLab.Encodings.SymbolicExpressionTreeEncoding {
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[3512] | 29 | [StorableClass]
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[4189] | 30 | [Item("ChangeNodeTypeManipulation", "Selects a random tree node and changes the symbol.")]
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[4722] | 31 | public sealed class ChangeNodeTypeManipulation : SymbolicExpressionTreeManipulator {
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[7662] | 32 | private const int MAX_TRIES = 100;
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| 33 |
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[4722] | 34 | [StorableConstructor]
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| 35 | private ChangeNodeTypeManipulation(bool deserializing) : base(deserializing) { }
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| 36 | private ChangeNodeTypeManipulation(ChangeNodeTypeManipulation original, Cloner cloner) : base(original, cloner) { }
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| 37 | public ChangeNodeTypeManipulation() : base() { }
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| 38 |
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| 39 | public override IDeepCloneable Clone(Cloner cloner) {
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| 40 | return new ChangeNodeTypeManipulation(this, cloner);
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[645] | 41 | }
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| 42 |
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[5510] | 43 | protected override void Manipulate(IRandom random, ISymbolicExpressionTree symbolicExpressionTree) {
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[5499] | 44 | ChangeNodeType(random, symbolicExpressionTree);
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[4189] | 45 | }
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[645] | 46 |
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[5510] | 47 | public static void ChangeNodeType(IRandom random, ISymbolicExpressionTree symbolicExpressionTree) {
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[7662] | 48 | List<ISymbol> allowedSymbols = new List<ISymbol>();
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| 49 | ISymbolicExpressionTreeNode parent;
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| 50 | int childIndex;
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| 51 | ISymbolicExpressionTreeNode child;
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| 52 | // repeat until a fitting parent and child are found (MAX_TRIES times)
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| 53 | int tries = 0;
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| 54 | do {
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| 55 | parent = symbolicExpressionTree.Root.IterateNodesPrefix().Skip(1).Where(n => n.SubtreeCount > 0).SelectRandom(random);
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| 56 | childIndex = random.Next(parent.SubtreeCount);
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[645] | 57 |
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[7662] | 58 | child = parent.GetSubtree(childIndex);
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| 59 | int existingSubtreeCount = child.SubtreeCount;
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| 60 | allowedSymbols.Clear();
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| 61 | foreach (var symbol in parent.Grammar.GetAllowedChildSymbols(parent.Symbol, childIndex)) {
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| 62 | // check basic properties that the new symbol must have
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| 63 | if (symbol.Name != child.Symbol.Name &&
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| 64 | symbol.InitialFrequency > 0 &&
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| 65 | existingSubtreeCount <= parent.Grammar.GetMinimumSubtreeCount(symbol) &&
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| 66 | existingSubtreeCount >= parent.Grammar.GetMaximumSubtreeCount(symbol)) {
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| 67 | // check that all existing subtrees are also allowed for the new symbol
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| 68 | bool allExistingSubtreesAllowed = true;
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| 69 | for (int existingSubtreeIndex = 0; existingSubtreeIndex < existingSubtreeCount && allExistingSubtreesAllowed; existingSubtreeIndex++) {
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| 70 | var existingSubtree = child.GetSubtree(existingSubtreeIndex);
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| 71 | allExistingSubtreesAllowed &= parent.Grammar.IsAllowedChildSymbol(symbol, existingSubtree.Symbol, existingSubtreeIndex);
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| 72 | }
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| 73 | if (allExistingSubtreesAllowed) {
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| 74 | allowedSymbols.Add(symbol);
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| 75 | }
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| 76 | }
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| 77 | }
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| 78 | tries++;
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| 79 | } while (tries < MAX_TRIES && allowedSymbols.Count == 0);
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[5567] | 80 |
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[7662] | 81 | if (tries < MAX_TRIES) {
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| 82 | var weights = allowedSymbols.Select(s => s.InitialFrequency).ToList();
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| 83 | var newSymbol = allowedSymbols.SelectRandom(weights, random);
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| 84 |
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| 85 | // replace the old node with the new node
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| 86 | var newNode = newSymbol.CreateTreeNode();
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| 87 | if (newNode.HasLocalParameters)
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| 88 | newNode.ResetLocalParameters(random);
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| 89 | foreach (var subtree in child.Subtrees)
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| 90 | newNode.AddSubtree(subtree);
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| 91 | parent.RemoveSubtree(childIndex);
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| 92 | parent.InsertSubtree(childIndex, newNode);
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| 93 | }
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[645] | 94 | }
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| 95 | }
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| 96 | }
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