hi i use porter algorithm for stemming words (stemming is the process of reducing inflected (or sometimes derived) words to their word stem, base or root form—generally a written word form. The stem need not be identical to the morphological root of the word; it is usually sufficient that related words map to the same stem, even if this stem is not in itself a valid root. for example, should identify the string
“cats” (and possibly “catlike”, “catty” etc.) as based on the root
“cat”, and “stems”, “stemmer”, “stemming”, “stemmed” as based on “stem”.) i hope you understand stemming now,
my porter algorithm have some problem,like Germany should remain Germany but its turn to “Germani” and family should remain same but changes to “famili” and military and beauty ,or “friendly” should turn to “friend” but its change to “friendli” or its make “uniqu” or “awesom” the letter “E” is deleted,and many problem like this, is there any porter better than this porter algorithm or other algorithm?
its current porter algorithm that i am using:
<?php
/**
* Copyright (c) 2005 Richard Heyes (http://www.phpguru.org/)
*
* All rights reserved.
*
* This script is free software.
*/
/**
* PHP5 Implementation of the Porter Stemmer algorithm. Certain elements
* were borrowed from the (broken) implementation by Jon Abernathy.
*
* Usage:
*
* $stem = PorterStemmer::Stem($word);
*
* How easy is that?
*/
class PorterStemmer
{
/**
* Regex for matching a consonant
* @var string
*/
private static $regex_consonant = '(?:[bcdfghjklmnpqrstvwxz]|(?<=[aeiou])y|^y)';
/**
* Regex for matching a vowel
* @var string
*/
private static $regex_vowel = '(?:[aeiou]|(?<![aeiou])y)';
/**
* Stems a word. Simple huh?
*
* @param string $word Word to stem
* @return string Stemmed word
*/
public static function Stem($word)
{
if (strlen($word) <= 2) {
return $word;
}
$word = self::step1ab($word);
$word = self::step1c($word);
$word = self::step2($word);
$word = self::step3($word);
$word = self::step4($word);
$word = self::step5($word);
return $word;
}
/**
* Step 1
*/
private static function step1ab($word)
{
// Part a
if (substr($word, -1) == 's') {
self::replace($word, 'sses', 'ss')
OR self::replace($word, 'ies', 'i')
OR self::replace($word, 'ss', 'ss')
OR self::replace($word, 's', '');
}
// Part b
if (substr($word, -2, 1) != 'e' OR !self::replace($word, 'eed', 'ee', 0)) { // First rule
$v = self::$regex_vowel;
// ing and ed
if ( preg_match("#$v+#", substr($word, 0, -3)) && self::replace($word, 'ing', '')
OR preg_match("#$v+#", substr($word, 0, -2)) && self::replace($word, 'ed', '')) { // Note use of && and OR, for precedence reasons
// If one of above two test successful
if ( !self::replace($word, 'at', 'ate')
AND !self::replace($word, 'bl', 'ble')
AND !self::replace($word, 'iz', 'ize')) {
// Double consonant ending
if ( self::doubleConsonant($word)
AND substr($word, -2) != 'll'
AND substr($word, -2) != 'ss'
AND substr($word, -2) != 'zz') {
$word = substr($word, 0, -1);
} else if (self::m($word) == 1 AND self::cvc($word)) {
$word .= 'e';
}
}
}
}
return $word;
}
/**
* Step 1c
*
* @param string $word Word to stem
*/
private static function step1c($word)
{
$v = self::$regex_vowel;
if (substr($word, -1) == 'y' && preg_match("#$v+#", substr($word, 0, -1))) {
self::replace($word, 'y', 'i');
}
return $word;
}
/**
* Step 2
*
* @param string $word Word to stem
*/
private static function step2($word)
{
switch (substr($word, -2, 1)) {
case 'a':
self::replace($word, 'ational', 'ate', 0)
OR self::replace($word, 'tional', 'tion', 0);
break;
case 'c':
self::replace($word, 'enci', 'ence', 0)
OR self::replace($word, 'anci', 'ance', 0);
break;
case 'e':
self::replace($word, 'izer', 'ize', 0);
break;
case 'g':
self::replace($word, 'logi', 'log', 0);
break;
case 'l':
self::replace($word, 'entli', 'ent', 0)
OR self::replace($word, 'ousli', 'ous', 0)
OR self::replace($word, 'alli', 'al', 0)
OR self::replace($word, 'bli', 'ble', 0)
OR self::replace($word, 'eli', 'e', 0);
break;
case 'o':
self::replace($word, 'ization', 'ize', 0)
OR self::replace($word, 'ation', 'ate', 0)
OR self::replace($word, 'ator', 'ate', 0);
break;
case 's':
self::replace($word, 'iveness', 'ive', 0)
OR self::replace($word, 'fulness', 'ful', 0)
OR self::replace($word, 'ousness', 'ous', 0)
OR self::replace($word, 'alism', 'al', 0);
break;
case 't':
self::replace($word, 'biliti', 'ble', 0)
OR self::replace($word, 'aliti', 'al', 0)
OR self::replace($word, 'iviti', 'ive', 0);
break;
}
return $word;
}
/**
* Step 3
*
* @param string $word String to stem
*/
private static function step3($word)
{
switch (substr($word, -2, 1)) {
case 'a':
self::replace($word, 'ical', 'ic', 0);
break;
case 's':
self::replace($word, 'ness', '', 0);
break;
case 't':
self::replace($word, 'icate', 'ic', 0)
OR self::replace($word, 'iciti', 'ic', 0);
break;
case 'u':
self::replace($word, 'ful', '', 0);
break;
case 'v':
self::replace($word, 'ative', '', 0);
break;
case 'z':
self::replace($word, 'alize', 'al', 0);
break;
}
return $word;
}
/**
* Step 4
*
* @param string $word Word to stem
*/
private static function step4($word)
{
switch (substr($word, -2, 1)) {
case 'a':
self::replace($word, 'al', '', 1);
break;
case 'c':
self::replace($word, 'ance', '', 1)
OR self::replace($word, 'ence', '', 1);
break;
case 'e':
self::replace($word, 'er', '', 1);
break;
case 'i':
self::replace($word, 'ic', '', 1);
break;
case 'l':
self::replace($word, 'able', '', 1)
OR self::replace($word, 'ible', '', 1);
break;
case 'n':
self::replace($word, 'ant', '', 1)
OR self::replace($word, 'ement', '', 1)
OR self::replace($word, 'ment', '', 1)
OR self::replace($word, 'ent', '', 1);
break;
case 'o':
if (substr($word, -4) == 'tion' OR substr($word, -4) == 'sion') {
self::replace($word, 'ion', '', 1);
} else {
self::replace($word, 'ou', '', 1);
}
break;
case 's':
self::replace($word, 'ism', '', 1);
break;
case 't':
self::replace($word, 'ate', '', 1)
OR self::replace($word, 'iti', '', 1);
break;
case 'u':
self::replace($word, 'ous', '', 1);
break;
case 'v':
self::replace($word, 'ive', '', 1);
break;
case 'z':
self::replace($word, 'ize', '', 1);
break;
}
return $word;
}
/**
* Step 5
*
* @param string $word Word to stem
*/
private static function step5($word)
{
// Part a
if (substr($word, -1) == 'e') {
if (self::m(substr($word, 0, -1)) > 1) {
self::replace($word, 'e', '');
} else if (self::m(substr($word, 0, -1)) == 1) {
if (!self::cvc(substr($word, 0, -1))) {
self::replace($word, 'e', '');
}
}
}
// Part b
if (self::m($word) > 1 AND self::doubleConsonant($word) AND substr($word, -1) == 'l') {
$word = substr($word, 0, -1);
}
return $word;
}
/**
* Replaces the first string with the second, at the end of the string. If third
* arg is given, then the preceding string must match that m count at least.
*
* @param string $str String to check
* @param string $check Ending to check for
* @param string $repl Replacement string
* @param int $m Optional minimum number of m() to meet
* @return bool Whether the $check string was at the end
* of the $str string. True does not necessarily mean
* that it was replaced.
*/
private static function replace(&$str, $check, $repl, $m = null)
{
$len = 0 - strlen($check);
if (substr($str, $len) == $check) {
$substr = substr($str, 0, $len);
if (is_null($m) OR self::m($substr) > $m) {
$str = $substr . $repl;
}
return true;
}
return false;
}
/**
* What, you mean it's not obvious from the name?
*
* m() measures the number of consonant sequences in $str. if c is
* a consonant sequence and v a vowel sequence, and <..> indicates arbitrary
* presence,
*
* <c><v> gives 0
* <c>vc<v> gives 1
* <c>vcvc<v> gives 2
* <c>vcvcvc<v> gives 3
*
* @param string $str The string to return the m count for
* @return int The m count
*/
private static function m($str)
{
$c = self::$regex_consonant;
$v = self::$regex_vowel;
$str = preg_replace("#^$c+#", '', $str);
$str = preg_replace("#$v+$#", '', $str);
preg_match_all("#($v+$c+)#", $str, $matches);
return count($matches[1]);
}
/**
* Returns true/false as to whether the given string contains two
* of the same consonant next to each other at the end of the string.
*
* @param string $str String to check
* @return bool Result
*/
private static function doubleConsonant($str)
{
$c = self::$regex_consonant;
return preg_match("#$c{2}$#", $str, $matches) AND $matches[0]{0} == $matches[0]{1};
}
/**
* Checks for ending CVC sequence where second C is not W, X or Y
*
* @param string $str String to check
* @return bool Result
*/
private static function cvc($str)
{
$c = self::$regex_consonant;
$v = self::$regex_vowel;
return preg_match("#($c$v$c)$#", $str, $matches)
AND strlen($matches[1]) == 3
AND $matches[1]{2} != 'w'
AND $matches[1]{2} != 'x'
AND $matches[1]{2} != 'y';
}
}
?>
and with this example you can use this class in other files 
require_once 'porter.php';
$stem = PorterStemmer::Stem($word);
$stem_words[] = $stem;
i am waiting for your valuable helps…