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Statistical parsing of English sentences

, 13 Dec 2006
Shows how to generate parse trees for English language sentences, using a C# port of OpenNLP, a statistical natural language parsing library.
englishparsing_bin.zip
Lithium.dll
ModelConverter.exe
OpenNLP Tools.chm
OpenNLP.dll
ParseTree.exe
SharpEntropy.dll
ToolsExample.exe
englishparsing_net2_0_bin.zip
ToolsExample.exe
Lithium.dll
ModelConverter.exe
OpenNLP Tools.chm
OpenNLP.dll
ParseTree.exe
SharpEntropy.dll
englishparsing_net2_0_src.zip
Lithium
Collections
Delegates
Enums
Interfaces
IO
Lithium.csproj.vspscc
LithiumControl.bmp
Shapes
UI
Visitors
ModelConverter
App.ico
ModelConverter.csproj.vspscc
ParseTree
App.ico
ParseTree.csproj.vspscc
ToolsExample
App.ico
ToolsExample.csproj.vspscc
OpenNLP
OpenNLP.csproj.vspscc
SharpEntropy.dll
Tools
Chunker
NameFind
Parser
PosTagger
SentenceDetect
Tokenize
Util
englishparsing_src.zip
Lithium.csproj.user
LithiumControl.bmp
App.ico
ModelConverter.csproj.user
OpenNLP.csproj.user
SharpEntropy.dll
vssver.scc
vssver.scc
vssver.scc
vssver.scc
vssver.scc
vssver.scc
vssver.scc
App.ico
ParseTree.csproj.user
App.ico
ToolsExample.csproj.user
//Copyright (C) 2005 Richard J. Northedge
//
// This library is free software; you can redistribute it and/or
// modify it under the terms of the GNU Lesser General Public
// License as published by the Free Software Foundation; either
// version 2.1 of the License, or (at your option) any later version.
//
// This library 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 Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public
// License along with this program; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.

//This file is based on the POSDictionary.java source file found in the
//original java implementation of OpenNLP.  That source file contains the following header:

//Copyright (C) 2004 Thomas Morton
// 
//This library is free software; you can redistribute it and/or
//modify it under the terms of the GNU Lesser General Public
//License as published by the Free Software Foundation; either
//version 2.1 of the License, or (at your option) any later version.
// 
//This library 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 Lesser General Public License for more details.
// 
//You should have received a copy of the GNU Lesser General Public
//License along with this program; if not, write to the Free Software
//Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.

using System;
using System.Collections.Generic;

namespace OpenNLP.Tools.PosTagger
{
	/// <summary>
	/// Provides a means of determining which tags are valid for a particular word based on a tag dictionary read from a file.
	/// </summary>
	public class PosLookupList
	{
		private Dictionary<string, string[]> mDictionary;
		private bool mIsCaseSensitive;
		
		public PosLookupList(string file) : this(file, true)
		{
		}
		
		/// <summary>
		/// Create tag dictionary object with contents of specified file and using specified case to determine how to access entries in the tag dictionary.
		/// </summary>
		/// <param name="file">
		/// The file name for the tag dictionary.
		/// </param>
		/// <param name="caseSensitive">
		/// Specifies whether the tag dictionary is case sensitive or not.
		/// </param>
		public PosLookupList(string file, bool caseSensitive) : this(new System.IO.StreamReader(file, System.Text.Encoding.UTF7), caseSensitive)
		{
		}
		
		/// <summary>
		/// Create tag dictionary object with contents of specified file and using specified case to determine how to access entries in the tag dictionary.
		/// </summary>
		/// <param name="reader">
		/// A reader for the tag dictionary.
		/// </param>
		/// <param name="caseSensitive">
		/// Specifies whether the tag dictionary is case sensitive or not.
		/// </param>
		public PosLookupList(System.IO.StreamReader reader, bool caseSensitive)
		{
            mDictionary = new Dictionary<string, string[]>();
			mIsCaseSensitive = caseSensitive;
			for (string line = reader.ReadLine(); line != null; line = reader.ReadLine())
			{
				string[] parts = line.Split(' ');
				string[] tags = new string[parts.Length - 1];
				for (int currentTag = 0, tagCount = parts.Length - 1; currentTag < tagCount; currentTag++)
				{
					tags[currentTag] = parts[currentTag + 1];
				}
				mDictionary[parts[0]] = tags;
			}
		}
		
		/// <summary>
		/// Returns a list of valid tags for the specified word. </summary>
		/// <param name="word">
		/// The word.
		/// </param>
		/// <returns>
		/// A list of valid tags for the specified word or null if no information is available for that word.
		/// </returns>
		public virtual string[] GetTags(string word)
		{
			if (!mIsCaseSensitive)
			{
                word = word.ToLower(System.Globalization.CultureInfo.InvariantCulture);
            }

            if (mDictionary.ContainsKey(word))
            {
			    return mDictionary[word];
            }
            else
            {
                return null;
            }
		}
	}
}

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About the Author

Richard Northedge
Web Developer
United Kingdom United Kingdom
Richard Northedge is a senior developer with a UK Microsoft Gold Partner company. He has a postgraduate degree in English Literature, has been programming professionally since 1998 and has been an MCSD since 2000.

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