48 lines
1.5 KiB
C#
48 lines
1.5 KiB
C#
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/*
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* BotSharp.NLP Library
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* Copyright (C) 2018 Haiping Chen
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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using System;
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using System.Collections.Generic;
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using System.Linq;
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using System.Text;
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using System.Text.RegularExpressions;
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using BotSharp.NLP.Tokenize;
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namespace BotSharp.NLP.Stem
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{
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/// <summary>
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/// A stemmer that uses regular expressions to identify morphological affixes.
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/// Any substrings that match the regular expressions will be removed.
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/// </summary>
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public class RegexStemmer : IStemmer
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{
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public const string DEFAULT = "ing$|s$|e$|able$";
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private Regex _regex;
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public string Stem(string word, StemOptions options)
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{
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_regex = new Regex(options.Pattern);
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var match = _regex.Matches(word).Cast<Match>().FirstOrDefault();
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return match == null ? word : word.Substring(0, match.Index);
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}
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}
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}
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