#region License Information
/* HeuristicLab
* Copyright (C) 2002-2010 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.Core;
using HeuristicLab.Data;
using HeuristicLab.Operators;
using HeuristicLab.Optimization;
using HeuristicLab.Parameters;
using HeuristicLab.Persistence.Default.CompositeSerializers.Storable;
using HeuristicLab.Encodings.SymbolicExpressionTreeEncoding.GeneralSymbols;
using System.Collections.Generic;
using System.Text;
using System.Diagnostics;
namespace HeuristicLab.Encodings.SymbolicExpressionTreeEncoding.ArchitectureAlteringOperators {
///
/// Manipulates a symbolic expression by duplicating a preexisting function-defining branch.
/// As described in Koza, Bennett, Andre, Keane, Genetic Programming III - Darwinian Invention and Problem Solving, 1999, pp. 88
///
[Item("SubroutineDuplicater", "Manipulates a symbolic expression by duplicating a preexisting function-defining branch.")]
[StorableClass]
public sealed class SubroutineDuplicater : SymbolicExpressionTreeArchitectureAlteringOperator {
public override sealed void ModifyArchitecture(
IRandom random,
SymbolicExpressionTree symbolicExpressionTree,
ISymbolicExpressionGrammar grammar,
IntValue maxTreeSize, IntValue maxTreeHeight,
IntValue maxFunctionDefiningBranches, IntValue maxFunctionArguments,
out bool success) {
success = DuplicateRandomSubroutine(random, symbolicExpressionTree, grammar, maxTreeSize.Value, maxTreeHeight.Value, maxFunctionDefiningBranches.Value, maxFunctionArguments.Value);
}
public static bool DuplicateRandomSubroutine(
IRandom random,
SymbolicExpressionTree symbolicExpressionTree,
ISymbolicExpressionGrammar grammar,
int maxTreeSize, int maxTreeHeight,
int maxFunctionDefiningBranches, int maxFunctionArguments) {
var functionDefiningBranches = symbolicExpressionTree.IterateNodesPrefix().OfType();
string formatString = new StringBuilder().Append('0', (int)Math.Log10(maxFunctionDefiningBranches) + 1).ToString(); // >= 100 functions => ###
var allowedFunctionNames = from index in Enumerable.Range(0, maxFunctionDefiningBranches)
select "ADF" + index.ToString(formatString);
if (functionDefiningBranches.Count() == 0 || functionDefiningBranches.Count() == maxFunctionDefiningBranches)
// no function defining branches to duplicate or already reached the max number of ADFs
return false;
var selectedBranch = functionDefiningBranches.SelectRandom(random);
var clonedBranch = (DefunTreeNode)selectedBranch.Clone();
clonedBranch.Name = allowedFunctionNames.Except(UsedFunctionNames(symbolicExpressionTree)).First();
foreach (var node in symbolicExpressionTree.IterateNodesPrefix()) {
var invokeFunctionNode = node as InvokeFunctionTreeNode;
// find all invokations of the old function
if (invokeFunctionNode != null && invokeFunctionNode.InvokedFunctionName == selectedBranch.Name) {
// add the new function name to the list of known functions in the branches that used the originating function
var branch = symbolicExpressionTree.GetTopLevelBranchOf(invokeFunctionNode);
branch.AddDynamicSymbol(clonedBranch.Name, clonedBranch.NumberOfArguments);
// flip coin wether to replace with newly defined function
if (random.NextDouble() < 0.5) {
invokeFunctionNode.InvokedFunctionName = clonedBranch.Name;
}
}
}
Debug.Assert(grammar.IsValidExpression(symbolicExpressionTree));
return true;
}
private static bool ContainsNode(SymbolicExpressionTreeNode branch, SymbolicExpressionTreeNode node) {
if (branch == node) return true;
else foreach (var subtree in branch.SubTrees) {
if (ContainsNode(subtree, node)) return true;
}
return false;
}
private static IEnumerable UsedFunctionNames(SymbolicExpressionTree symbolicExpressionTree) {
return from node in symbolicExpressionTree.IterateNodesPrefix()
where node.Symbol is Defun
select ((DefunTreeNode)node).Name;
}
}
}