#region License Information
/* HeuristicLab
* Copyright (C) 2002-2016 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.Collections.Generic;
using System.Globalization;
using System.Linq;
using System.Text;
using HeuristicLab.Common;
using HeuristicLab.Core;
using HeuristicLab.Encodings.SymbolicExpressionTreeEncoding;
using HeuristicLab.Persistence.Default.CompositeSerializers.Storable;
namespace HeuristicLab.Problems.DataAnalysis.Symbolic {
///
/// Formats mathematical expressions in infix form. E.g. x1 * (3.0 * x2 + x3)
///
[StorableClass]
[Item("Infix Symbolic Expression Tree Formatter", "A string formatter that converts symbolic expression trees to infix expressions.")]
public sealed class InfixExpressionFormatter : NamedItem, ISymbolicExpressionTreeStringFormatter {
[StorableConstructor]
private InfixExpressionFormatter(bool deserializing) : base(deserializing) { }
private InfixExpressionFormatter(InfixExpressionFormatter original, Cloner cloner) : base(original, cloner) { }
public InfixExpressionFormatter()
: base() {
Name = ItemName;
Description = ItemDescription;
}
public override IDeepCloneable Clone(Cloner cloner) {
return new InfixExpressionFormatter(this, cloner);
}
public string Format(ISymbolicExpressionTree symbolicExpressionTree) {
// skip root and start symbols
StringBuilder strBuilder = new StringBuilder();
FormatRecursively(symbolicExpressionTree.Root.GetSubtree(0).GetSubtree(0), strBuilder);
return strBuilder.ToString();
}
private void FormatRecursively(ISymbolicExpressionTreeNode node, StringBuilder strBuilder) {
if (node.SubtreeCount > 1) {
var token = GetToken(node.Symbol);
if (token == "+" || token == "-" || token == "OR" || token == "XOR") {
strBuilder.Append("(");
FormatRecursively(node.Subtrees.First(), strBuilder);
foreach (var subtree in node.Subtrees.Skip(1)) {
strBuilder.Append(" ").Append(token).Append(" ");
FormatRecursively(subtree, strBuilder);
}
strBuilder.Append(")");
} else if (token == "*" || token == "/" || token == "AND") {
strBuilder.Append("(");
FormatRecursively(node.Subtrees.First(), strBuilder);
foreach (var subtree in node.Subtrees.Skip(1)) {
strBuilder.Append(" ").Append(token).Append(" ");
FormatRecursively(subtree, strBuilder);
}
strBuilder.Append(")");
} else {
// function with multiple arguments
strBuilder.Append(token).Append("(");
FormatRecursively(node.Subtrees.First(), strBuilder);
foreach (var subtree in node.Subtrees.Skip(1)) {
strBuilder.Append(", ");
FormatRecursively(subtree, strBuilder);
}
strBuilder.Append(")");
}
} else if (node.SubtreeCount == 1) {
var token = GetToken(node.Symbol);
if (token == "-" || token == "NOT") {
strBuilder.Append("(").Append(token).Append("(");
FormatRecursively(node.GetSubtree(0), strBuilder);
strBuilder.Append("))");
} else if (token == "/") {
strBuilder.Append("1/");
FormatRecursively(node.GetSubtree(0), strBuilder);
} else if (token == "+" || token == "*") {
FormatRecursively(node.GetSubtree(0), strBuilder);
} else {
// function with only one argument
strBuilder.Append(token).Append("(");
FormatRecursively(node.GetSubtree(0), strBuilder);
strBuilder.Append(")");
}
} else {
// no subtrees
if (node.Symbol is LaggedVariable) {
var varNode = node as LaggedVariableTreeNode;
if (!varNode.Weight.IsAlmost(1.0)) {
strBuilder.Append("(");
strBuilder.AppendFormat(CultureInfo.InvariantCulture, "{0}", varNode.Weight);
strBuilder.Append("*");
}
strBuilder.Append("LAG(");
if (varNode.VariableName.Contains("'")) {
strBuilder.AppendFormat("\"{0}\"", varNode.VariableName);
} else {
strBuilder.AppendFormat("'{0}'", varNode.VariableName);
}
strBuilder.Append(", ")
.AppendFormat(CultureInfo.InvariantCulture, "{0}", varNode.Lag)
.Append(")");
} else if (node.Symbol is Variable) {
var varNode = node as VariableTreeNode;
if (!varNode.Weight.IsAlmost(1.0)) {
strBuilder.Append("(");
strBuilder.AppendFormat(CultureInfo.InvariantCulture, "{0}", varNode.Weight);
strBuilder.Append("*");
}
if (varNode.VariableName.Contains("'")) {
strBuilder.AppendFormat("\"{0}\"", varNode.VariableName);
} else {
strBuilder.AppendFormat("'{0}'", varNode.VariableName);
}
if (!varNode.Weight.IsAlmost(1.0)) {
strBuilder.Append(")");
}
} else if (node.Symbol is Constant) {
var constNode = node as ConstantTreeNode;
if (constNode.Value >= 0.0)
strBuilder.AppendFormat(CultureInfo.InvariantCulture, "{0}", constNode.Value);
else
strBuilder.AppendFormat(CultureInfo.InvariantCulture, "({0})", constNode.Value); // (-1
}
}
}
private string GetToken(ISymbol symbol) {
var tok = InfixExpressionParser.knownSymbols.GetBySecond(symbol).SingleOrDefault();
if (tok == null)
throw new ArgumentException(string.Format("Unknown symbol {0} found.", symbol.Name));
return tok;
}
}
}