[3294] | 1 | #region License Information
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| 2 | /* HeuristicLab
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[14186] | 3 | * Copyright (C) 2002-2016 Heuristic and Evolutionary Algorithms Laboratory (HEAL)
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[3294] | 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;
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| 23 | using System.Linq;
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[4722] | 24 | using HeuristicLab.Common;
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[3294] | 25 | using HeuristicLab.Core;
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| 26 | using HeuristicLab.Data;
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| 27 | using HeuristicLab.Persistence.Default.CompositeSerializers.Storable;
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[12706] | 28 | using HeuristicLab.Random;
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[3294] | 29 |
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[5499] | 30 | namespace HeuristicLab.Encodings.SymbolicExpressionTreeEncoding {
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[3294] | 31 | /// <summary>
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| 32 | /// Manipulates a symbolic expression by deleting a preexisting function-defining branch.
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| 33 | /// As described in Koza, Bennett, Andre, Keane, Genetic Programming III - Darwinian Invention and Problem Solving, 1999, pp. 108
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| 34 | /// </summary>
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[5510] | 35 | [Item("SubroutineDeleter", "Manipulates a symbolic expression by deleting a preexisting function-defining branch. As described in Koza, Bennett, Andre, Keane, Genetic Programming III - Darwinian Invention and Problem Solving, 1999, pp. 108")]
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[3294] | 36 | [StorableClass]
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[3534] | 37 | public sealed class SubroutineDeleter : SymbolicExpressionTreeArchitectureManipulator {
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[4722] | 38 | [StorableConstructor]
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| 39 | private SubroutineDeleter(bool deserializing) : base(deserializing) { }
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| 40 | private SubroutineDeleter(SubroutineDeleter original, Cloner cloner) : base(original, cloner) { }
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| 41 | public SubroutineDeleter() : base() { }
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| 42 |
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| 43 | public override IDeepCloneable Clone(Cloner cloner) {
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| 44 | return new SubroutineDeleter(this, cloner);
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| 45 | }
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| 46 |
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[3294] | 47 | public override sealed void ModifyArchitecture(
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| 48 | IRandom random,
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[5510] | 49 | ISymbolicExpressionTree symbolicExpressionTree,
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| 50 | IntValue maxFunctionDefinitions, IntValue maxFunctionArguments) {
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| 51 | DeleteSubroutine(random, symbolicExpressionTree, maxFunctionDefinitions.Value, maxFunctionArguments.Value);
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[3294] | 52 | }
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| 53 |
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| 54 | public static bool DeleteSubroutine(
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| 55 | IRandom random,
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[5510] | 56 | ISymbolicExpressionTree symbolicExpressionTree,
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| 57 | int maxFunctionDefinitions, int maxFunctionArguments) {
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[12706] | 58 | var functionDefiningBranches = symbolicExpressionTree.IterateNodesPrefix().OfType<DefunTreeNode>().ToList();
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[3294] | 59 |
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[12706] | 60 | if (!functionDefiningBranches.Any())
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[3294] | 61 | // no ADF to delete => abort
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| 62 | return false;
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[12706] | 63 |
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| 64 | var selectedDefunBranch = functionDefiningBranches.SampleRandom(random);
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[3294] | 65 | // remove the selected defun
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[5733] | 66 | int defunSubtreeIndex = symbolicExpressionTree.Root.IndexOfSubtree(selectedDefunBranch);
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| 67 | symbolicExpressionTree.Root.RemoveSubtree(defunSubtreeIndex);
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[3294] | 68 |
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| 69 | // remove references to deleted function
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[5733] | 70 | foreach (var subtree in symbolicExpressionTree.Root.Subtrees.OfType<SymbolicExpressionTreeTopLevelNode>()) {
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[3360] | 71 | var matchingInvokeSymbol = (from symb in subtree.Grammar.Symbols.OfType<InvokeFunction>()
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| 72 | where symb.FunctionName == selectedDefunBranch.FunctionName
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| 73 | select symb).SingleOrDefault();
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| 74 | if (matchingInvokeSymbol != null) {
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| 75 | subtree.Grammar.RemoveSymbol(matchingInvokeSymbol);
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[3294] | 76 | }
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| 77 | }
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[3360] | 78 |
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| 79 | DeletionByRandomRegeneration(random, symbolicExpressionTree, selectedDefunBranch);
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[3294] | 80 | return true;
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| 81 | }
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[3360] | 82 |
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[5510] | 83 | private static void DeletionByRandomRegeneration(IRandom random, ISymbolicExpressionTree symbolicExpressionTree, DefunTreeNode selectedDefunBranch) {
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[3360] | 84 | // find first invocation and replace it with a randomly generated tree
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| 85 | // can't find all invocations in one step because once we replaced a top level invocation
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| 86 | // the invocations below it are removed already
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| 87 | var invocationCutPoint = (from node in symbolicExpressionTree.IterateNodesPrefix()
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[5733] | 88 | from subtree in node.Subtrees.OfType<InvokeFunctionTreeNode>()
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[3360] | 89 | where subtree.Symbol.FunctionName == selectedDefunBranch.FunctionName
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[5686] | 90 | select new CutPoint(node, subtree)).FirstOrDefault();
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[3360] | 91 | while (invocationCutPoint != null) {
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| 92 | // deletion by random regeneration
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[5510] | 93 | ISymbolicExpressionTreeNode replacementTree = null;
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[5686] | 94 | var allowedSymbolsList = invocationCutPoint.Parent.Grammar.GetAllowedChildSymbols(invocationCutPoint.Parent.Symbol, invocationCutPoint.ChildIndex).ToList();
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[5411] | 95 | var weights = allowedSymbolsList.Select(s => s.InitialFrequency);
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[12706] | 96 |
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| 97 | #pragma warning disable 612, 618
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[5411] | 98 | var selectedSymbol = allowedSymbolsList.SelectRandom(weights, random);
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[12706] | 99 | #pragma warning restore 612, 618
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[3360] | 100 |
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[12706] | 101 |
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[5686] | 102 | int minPossibleLength = invocationCutPoint.Parent.Grammar.GetMinimumExpressionLength(selectedSymbol);
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| 103 | int maxLength = Math.Max(minPossibleLength, invocationCutPoint.Child.GetLength());
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| 104 | int minPossibleDepth = invocationCutPoint.Parent.Grammar.GetMinimumExpressionDepth(selectedSymbol);
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| 105 | int maxDepth = Math.Max(minPossibleDepth, invocationCutPoint.Child.GetDepth());
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[3369] | 106 | replacementTree = selectedSymbol.CreateTreeNode();
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[3535] | 107 | if (replacementTree.HasLocalParameters)
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| 108 | replacementTree.ResetLocalParameters(random);
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[5733] | 109 | invocationCutPoint.Parent.RemoveSubtree(invocationCutPoint.ChildIndex);
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| 110 | invocationCutPoint.Parent.InsertSubtree(invocationCutPoint.ChildIndex, replacementTree);
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[3360] | 111 |
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[5686] | 112 | ProbabilisticTreeCreator.PTC2(random, replacementTree, maxLength, maxDepth);
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[3369] | 113 |
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[3360] | 114 | invocationCutPoint = (from node in symbolicExpressionTree.IterateNodesPrefix()
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[5733] | 115 | from subtree in node.Subtrees.OfType<InvokeFunctionTreeNode>()
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[3360] | 116 | where subtree.Symbol.FunctionName == selectedDefunBranch.FunctionName
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[5686] | 117 | select new CutPoint(node, subtree)).FirstOrDefault();
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[3360] | 118 | }
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| 119 | }
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[3294] | 120 | }
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| 121 | }
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