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source: branches/HeuristicLab.ExpressionGenerator/HeuristicLab.ExpressionGenerator/3.4/ExpressionTemplate.cs @ 14411

Last change on this file since 14411 was 14411, checked in by bburlacu, 7 years ago

#2704: Slightly improve usage of ExpressionTemplate class.

File size: 3.5 KB
Line 
1#region License Information
2/* HeuristicLab
3 * Copyright (C) 2002-2016 Heuristic and Evolutionary Algorithms Laboratory (HEAL)
4 *
5 * This file is part of HeuristicLab.
6 *
7 * HeuristicLab is free software: you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License as published by
9 * the Free Software Foundation, either version 3 of the License, or
10 * (at your option) any later version.
11 *
12 * HeuristicLab is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
15 * GNU General Public License for more details.
16 *
17 * You should have received a copy of the GNU General Public License
18 * along with HeuristicLab. If not, see <http://www.gnu.org/licenses/>.
19 */
20#endregion
21
22using System;
23using System.Collections.Generic;
24using System.Linq;
25using HeuristicLab.Core;
26using HeuristicLab.Random;
27
28namespace HeuristicLab.ExpressionGenerator {
29  public abstract class ExpressionTemplate {
30    private List<Tuple<Expression, double>> arguments;
31    private readonly Func<IEnumerable<double>, double> transform;
32    private readonly string label;
33
34    protected Expression Instantiate(IRandom random, int n, bool sampleWithRepetition = false) {
35      var weights = arguments.Select(x => x.Item2);
36      var args = sampleWithRepetition
37       ? arguments.SampleProportional(random, n, weights).Select(x => x.Item1)
38       : arguments.SampleProportionalWithoutRepetition(random, n, weights).Select(x => x.Item1);
39      return Expression.Function(label, transform, args);
40    }
41
42    public abstract Expression Instantiate(IRandom random, bool sampleWithRepetition = false);
43
44    protected ExpressionTemplate(string label, Func<IEnumerable<double>, double> transform) {
45      this.transform = transform;
46      this.label = label;
47    }
48
49    public void AddArgument(Expression expression, double priority = 1d) {
50      arguments = arguments ?? new List<Tuple<Expression, double>>();
51      arguments.Add(Tuple.Create(expression, priority));
52    }
53
54    public void AddArguments(IEnumerable<Expression> expressions) {
55      arguments = arguments ?? new List<Tuple<Expression, double>>();
56      arguments.AddRange(expressions.Select(x => Tuple.Create(x, 1d)));
57    }
58
59    public void AddArguments(IEnumerable<Expression> expressions, IEnumerable<double> priorities) {
60      arguments = arguments ?? new List<Tuple<Expression, double>>();
61      arguments.AddRange(expressions.Zip(priorities, Tuple.Create));
62    }
63  }
64
65  public class RandomArityTemplate : ExpressionTemplate {
66    private readonly IRandom arityDistribution;
67
68    public RandomArityTemplate(string label, Func<IEnumerable<double>, double> transform, IRandom arityDistribution) : base(label, transform) {
69      this.arityDistribution = arityDistribution;
70    }
71
72    public override Expression Instantiate(IRandom random, bool sampleWithRepetition = false) {
73      var arity = (int)Math.Round(arityDistribution.NextDouble());
74      return Instantiate(random, arity, sampleWithRepetition);
75    }
76  }
77
78  public class FixedArityTemplate : ExpressionTemplate {
79    private readonly int arity;
80    public FixedArityTemplate(string label, Func<IEnumerable<double>, double> transform, int arity) : base(label, transform) {
81      this.arity = arity;
82    }
83
84    public override Expression Instantiate(IRandom random, bool sampleWithRepetition = false) {
85      return Instantiate(random, arity, sampleWithRepetition);
86    }
87  }
88}
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