I18N_Arabic

# Source for file Stemmer.php Documentation is available at Stemmer.php <?php /** * ---------------------------------------------------------------------- * * Copyright (c) 2006-2013 Khaled Al-Sham'aa. * * http://www.ar-php.org * * PHP Version 5 * * ---------------------------------------------------------------------- * * LICENSE * * This program is open source product; you can redistribute it and/or * modify it under the terms of the GNU Lesser General Public License (LGPL) * as published by the Free Software Foundation; either version 3 * of the License, or (at your option) any later version. * * This program 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, see <http://www.gnu.org/licenses/lgpl.txt>. * * ---------------------------------------------------------------------- * * Class Name: Arabic Text ArStemmer Class * * Filename: Stemmer.php * * Original Author(s): Khaled Al-Sham'aa <khaled@ar-php.org> * * Purpose: Get stem of an Arabic word * * ---------------------------------------------------------------------- * * Source: http://arabtechies.net/node/83 * By: Taha Zerrouki <taha.zerrouki@gmail.com> * * ---------------------------------------------------------------------- * * Arabic Word Stemmer Class * * PHP class to get stem of an Arabic word * * A stemmer is an automatic process in which morphological variants of terms * are mapped to a single representative string called a stem. Arabic belongs * to the Semitic family of languages which also includes Hebrew and Aramaic. * Since morphological change in Arabic results from the addition of prefixes * and infixes as well as suffixes, simple removal of suffixes is not as * effective for Arabic as it is for English. * * Arabic has much richer morphology than English. Arabic has two genders, * feminine and masculine; three numbers, singular, dual, and plural; and three * grammatical cases, nominative, genitive, and accusative. A noun has the * nominative case when it is a subject; accusative when it is the object of a * verb; and genitive when it is the object of a preposition. The form of an * Arabic noun is determined by its gender, number, and grammatical case. The * definitive nouns are formed by attaching the Arabic article "AL" to the * immediate front of the nouns. Besides prefixes, a noun can also carry a * suffix which is often a possessive pronoun. In Arabic, the conjunction word * "WA" (and) is often attached to the following word. * * Like nouns, an Arabic adjective can also have many variants. When an * adjective modifies a noun in a noun phrase, the adjective agrees with the * noun in gender, number, case, and definiteness. Arabic verbs have two tenses: * perfect and imperfect. Perfect tense denotes actions completed, while * imperfect denotes uncompleted actions. The imperfect tense has four mood: * indicative, subjective, jussive, and imperative. Arabic verbs in perfect * tense consist of a stem and a subject marker. The subject marker indicates * the person, gender, and number of the subject. The form of a verb in perfect * tense can have subject marker and pronoun suffix. The form of a * subject-marker is determined together by the person, gender, and number of * the subject. * Example: * <code> * include('./I18N/Arabic.php'); * $obj = new I18N_Arabic('Stemmer'); * * echo $obj->stem($word); * </code> * * @category I18N * @package I18N_Arabic * @author Khaled Al-Sham'aa <khaled@ar-php.org> * @copyright 2006-2013 Khaled Al-Sham'aa * * @license LGPL <http://www.gnu.org/licenses/lgpl.txt> * @link http://www.ar-php.org */ // New in PHP V5.3: Namespaces // namespace I18N\Arabic; // // $obj = new I18N\Arabic\Stemmer(); // // use I18N\Arabic; // $obj = new Arabic\Stemmer(); // // use I18N\Arabic\Stemmer as Stemmer; // $obj = new Stemmer(); /** * This PHP class get stem of an Arabic word * * @category I18N * @package I18N_Arabic * @author Khaled Al-Sham'aa <khaled@ar-php.org> * @copyright 2006-2013 Khaled Al-Sham'aa * * @license LGPL <http://www.gnu.org/licenses/lgpl.txt> * @link http://www.ar-php.org */ class I18N_Arabic_Stemmer { private static $_verbPre = 'وأسفلي'; private static $_verbPost = 'ومكانيه'; private static $_verbMay; private static $_verbMaxPre = 4; private static $_verbMaxPost = 6; private static $_verbMinStem = 2; private static $_nounPre = 'ابفكلوأ'; private static $_nounPost = 'اتةكمنهوي'; private static $_nounMay; private static $_nounMaxPre = 4; private static $_nounMaxPost = 6; private static $_nounMinStem = 2; /** * Loads initialize values * * @ignore */ public function __construct() { self::$_verbMay = self::$_verbPre . self::$_verbPost; self::$_nounMay = self::$_nounPre . self::$_nounPost; } /** * Get rough stem of the given Arabic word * * @param string $word Arabic word you would like to get its stem * * @return string Arabic stem of the word * @author Khaled Al-Sham'aa <khaled@ar-php.org> */ public static function stem($word) { $nounStem = self::roughStem( $word, self::$_nounMay, self::$_nounPre, self::$_nounPost, self::$_nounMaxPre, self::$_nounMaxPost, self::$_nounMinStem ); $verbStem = self::roughStem( $word, self::$_verbMay, self::$_verbPre, self::$_verbPost, self::$_verbMaxPre, self::$_verbMaxPost, self::$_verbMinStem ); if (mb_strlen($nounStem, 'UTF-8') < mb_strlen($verbStem, 'UTF-8')) { $stem = $nounStem; } else { $stem = $verbStem; } return $stem; } /** * Get rough stem of the given Arabic word (under specific rules) * * @param string $word Arabic word you would like to get its stem * @param string $notChars Arabic chars those can't be in postfix or prefix * @param string $preChars Arabic chars those may exists in the prefix * @param string $postChars Arabic chars those may exists in the postfix * @param integer $maxPre Max prefix length * @param integer $maxPost Max postfix length * @param integer $minStem Min stem length * * @return string Arabic stem of the word under giving rules * @author Khaled Al-Sham'aa <khaled@ar-php.org> */ protected static function roughStem ( $word, $notChars, $preChars, $postChars, $maxPre, $maxPost, $minStem ) { $right = -1; $left = -1; $max = mb_strlen($word, 'UTF-8'); for ($i=0; $i < $max; $i++) { if (mb_strpos($notChars, mb_substr($word, $i, 1, 'UTF-8'), 0, 'UTF-8') === false) { if ($right == -1) { $right = $i; } $left = $i; } } if ($right > $maxPre) { $right = $maxPre; } if ($max - $left - 1 > $maxPost) { $left = $max - $maxPost -1; } for ($i=0; $i < $right; $i++) { if (mb_strpos($preChars, mb_substr($word, $i, 1, 'UTF-8'), 0, 'UTF-8') === false) { $right = $i; break; } } for ($i=$max-1; $i>$left; $i--) { if (mb_strpos($postChars, mb_substr($word, $i, 1, 'UTF-8'), 0, 'UTF-8') === false) { $left = $i; break; } } if ($left - $right >= $minStem) { $stem = mb_substr($word, $right, $left-$right+1, 'UTF-8'); } else { $stem = null; } return $stem; } } Documentation generated on Mon, 14 Jan 2013 17:49:07 +0100 by phpDocumentor 1.4.0