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| /* | |
| * To change this template, choose Tools | Templates | |
| * and open the template in the editor. | |
| */ | |
| package tool.util; | |
| /* | |
| Porter stemmer in Java. The original paper is in | |
| Porter, 1980, An algorithm for suffix stripping, Program, Vol. 14, | |
| no. 3, pp 130-137, | |
| See also http://www.tartarus.org/~martin/PorterStemmer | |
| History: | |
| Release 1 | |
| Bug 1 (reported by Gonzalo Parra 16/10/99) fixed as marked below. | |
| The words 'aed', 'eed', 'oed' leave k at 'a' for step 3, and b[k-1] | |
| is then out outside the bounds of b. | |
| Release 2 | |
| Similarly, | |
| Bug 2 (reported by Steve Dyrdahl 22/2/00) fixed as marked below. | |
| 'ion' by itself leaves j = -1 in the test for 'ion' in step 5, and | |
| b[j] is then outside the bounds of b. | |
| Release 3 | |
| Considerably revised 4/9/00 in the light of many helpful suggestions | |
| from Brian Goetz of Quiotix Corporation (brian@quiotix.com). | |
| Release 4 | |
| */ | |
| import java.io.*; | |
| import java.util.ArrayList; | |
| import java.util.Arrays; | |
| import java.util.List; | |
| /** | |
| * Stemmer, implementing the Porter Stemming Algorithm | |
| * | |
| * The Stemmer class transforms a word into its root form. The input | |
| * word can be provided a character at time (by calling add()), or at once | |
| * by calling one of the various stem(something) methods. | |
| */ | |
| public class PorterStemmer | |
| { private char[] b; | |
| private int i, /* offset into b */ | |
| i_end, /* offset to end of stemmed word */ | |
| j, k; | |
| private static final int INC = 50; | |
| /* unit of size whereby b is increased */ | |
| public PorterStemmer() | |
| { b = new char[INC]; | |
| i = 0; | |
| i_end = 0; | |
| } | |
| /** | |
| * Add a character to the word being stemmed. When you are finished | |
| * adding characters, you can call stem(void) to stem the word. | |
| */ | |
| public void add(char ch) | |
| { if (i == b.length) | |
| { char[] new_b = new char[i+INC]; | |
| for (int c = 0; c < i; c++) new_b[c] = b[c]; | |
| b = new_b; | |
| } | |
| b[i++] = ch; | |
| } | |
| /** Adds wLen characters to the word being stemmed contained in a portion | |
| * of a char[] array. This is like repeated calls of add(char ch), but | |
| * faster. | |
| */ | |
| public void add(char[] w, int wLen) | |
| { if (i+wLen >= b.length) | |
| { char[] new_b = new char[i+wLen+INC]; | |
| for (int c = 0; c < i; c++) new_b[c] = b[c]; | |
| b = new_b; | |
| } | |
| for (int c = 0; c < wLen; c++) b[i++] = w[c]; | |
| } | |
| /** | |
| * After a word has been stemmed, it can be retrieved by toString(), | |
| * or a reference to the internal buffer can be retrieved by getResultBuffer | |
| * and getResultLength (which is generally more efficient.) | |
| */ | |
| public String toString() { return new String(b,0,i_end); } | |
| /** | |
| * Returns the length of the word resulting from the stemming process. | |
| */ | |
| public int getResultLength() { return i_end; } | |
| /** | |
| * Returns a reference to a character buffer containing the results of | |
| * the stemming process. You also need to consult getResultLength() | |
| * to determine the length of the result. | |
| */ | |
| public char[] getResultBuffer() { return b; } | |
| /* cons(i) is true <=> b[i] is a consonant. */ | |
| private final boolean cons(int i) | |
| { switch (b[i]) | |
| { case 'a': case 'e': case 'i': case 'o': case 'u': return false; | |
| case 'y': return (i==0) ? true : !cons(i-1); | |
| default: return true; | |
| } | |
| } | |
| /* m() measures the number of consonant sequences between 0 and j. 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 | |
| .... | |
| */ | |
| private final int m() | |
| { int n = 0; | |
| int i = 0; | |
| while(true) | |
| { if (i > j) return n; | |
| if (! cons(i)) break; i++; | |
| } | |
| i++; | |
| while(true) | |
| { while(true) | |
| { if (i > j) return n; | |
| if (cons(i)) break; | |
| i++; | |
| } | |
| i++; | |
| n++; | |
| while(true) | |
| { if (i > j) return n; | |
| if (! cons(i)) break; | |
| i++; | |
| } | |
| i++; | |
| } | |
| } | |
| /* vowelinstem() is true <=> 0,...j contains a vowel */ | |
| private final boolean vowelinstem() | |
| { int i; for (i = 0; i <= j; i++) if (! cons(i)) return true; | |
| return false; | |
| } | |
| /* doublec(j) is true <=> j,(j-1) contain a double consonant. */ | |
| private final boolean doublec(int j) | |
| { if (j < 1) return false; | |
| if (b[j] != b[j-1]) return false; | |
| return cons(j); | |
| } | |
| /* cvc(i) is true <=> i-2,i-1,i has the form consonant - vowel - consonant | |
| and also if the second c is not w,x or y. this is used when trying to | |
| restore an e at the end of a short word. e.g. | |
| cav(e), lov(e), hop(e), crim(e), but | |
| snow, box, tray. | |
| */ | |
| private final boolean cvc(int i) | |
| { if (i < 2 || !cons(i) || cons(i-1) || !cons(i-2)) return false; | |
| { int ch = b[i]; | |
| if (ch == 'w' || ch == 'x' || ch == 'y') return false; | |
| } | |
| return true; | |
| } | |
| private final boolean ends(String s) | |
| { int l = s.length(); | |
| int o = k-l+1; | |
| if (o < 0) return false; | |
| for (int i = 0; i < l; i++) if (b[o+i] != s.charAt(i)) return false; | |
| j = k-l; | |
| return true; | |
| } | |
| /* setto(s) sets (j+1),...k to the characters in the string s, readjusting | |
| k. */ | |
| private final void setto(String s) | |
| { int l = s.length(); | |
| int o = j+1; | |
| for (int i = 0; i < l; i++) b[o+i] = s.charAt(i); | |
| k = j+l; | |
| } | |
| /* r(s) is used further down. */ | |
| private final void r(String s) { if (m() > 0) setto(s); } | |
| /* step1() gets rid of plurals and -ed or -ing. e.g. | |
| caresses -> caress | |
| ponies -> poni | |
| ties -> ti | |
| caress -> caress | |
| cats -> cat | |
| feed -> feed | |
| agreed -> agree | |
| disabled -> disable | |
| matting -> mat | |
| mating -> mate | |
| meeting -> meet | |
| milling -> mill | |
| messing -> mess | |
| meetings -> meet | |
| */ | |
| private final void step1() | |
| { if (b[k] == 's') | |
| { if (ends("sses")) k -= 2; else | |
| if (ends("ies")) setto("i"); else | |
| if (b[k-1] != 's') k--; | |
| } | |
| if (ends("eed")) { if (m() > 0) k--; } else | |
| if ((ends("ed") || ends("ing")) && vowelinstem()) | |
| { k = j; | |
| if (ends("at")) setto("ate"); else | |
| if (ends("bl")) setto("ble"); else | |
| if (ends("iz")) setto("ize"); else | |
| if (doublec(k)) | |
| { k--; | |
| { int ch = b[k]; | |
| if (ch == 'l' || ch == 's' || ch == 'z') k++; | |
| } | |
| } | |
| else if (m() == 1 && cvc(k)) setto("e"); | |
| } | |
| } | |
| /* step2() turns terminal y to i when there is another vowel in the stem. */ | |
| private final void step2() { if (ends("y") && vowelinstem()) b[k] = 'i'; } | |
| /* step3() maps double suffices to single ones. so -ization ( = -ize plus | |
| -ation) maps to -ize etc. note that the string before the suffix must give | |
| m() > 0. */ | |
| private final void step3() { if (k == 0) return; /* For Bug 1 */ switch (b[k-1]) | |
| { | |
| case 'a': if (ends("ational")) { r("ate"); break; } | |
| if (ends("tional")) { r("tion"); break; } | |
| break; | |
| case 'c': if (ends("enci")) { r("ence"); break; } | |
| if (ends("anci")) { r("ance"); break; } | |
| break; | |
| case 'e': if (ends("izer")) { r("ize"); break; } | |
| break; | |
| case 'l': if (ends("bli")) { r("ble"); break; } | |
| if (ends("alli")) { r("al"); break; } | |
| if (ends("entli")) { r("ent"); break; } | |
| if (ends("eli")) { r("e"); break; } | |
| if (ends("ousli")) { r("ous"); break; } | |
| break; | |
| case 'o': if (ends("ization")) { r("ize"); break; } | |
| if (ends("ation")) { r("ate"); break; } | |
| if (ends("ator")) { r("ate"); break; } | |
| break; | |
| case 's': if (ends("alism")) { r("al"); break; } | |
| if (ends("iveness")) { r("ive"); break; } | |
| if (ends("fulness")) { r("ful"); break; } | |
| if (ends("ousness")) { r("ous"); break; } | |
| break; | |
| case 't': if (ends("aliti")) { r("al"); break; } | |
| if (ends("iviti")) { r("ive"); break; } | |
| if (ends("biliti")) { r("ble"); break; } | |
| break; | |
| case 'g': if (ends("logi")) { r("log"); break; } | |
| } } | |
| /* step4() deals with -ic-, -full, -ness etc. similar strategy to step3. */ | |
| private final void step4() { switch (b[k]) | |
| { | |
| case 'e': if (ends("icate")) { r("ic"); break; } | |
| if (ends("ative")) { r(""); break; } | |
| if (ends("alize")) { r("al"); break; } | |
| break; | |
| case 'i': if (ends("iciti")) { r("ic"); break; } | |
| break; | |
| case 'l': if (ends("ical")) { r("ic"); break; } | |
| if (ends("ful")) { r(""); break; } | |
| break; | |
| case 's': if (ends("ness")) { r(""); break; } | |
| break; | |
| } } | |
| /* step5() takes off -ant, -ence etc., in context <c>vcvc<v>. */ | |
| private final void step5() | |
| { if (k == 0) return; /* for Bug 1 */ switch (b[k-1]) | |
| { case 'a': if (ends("al")) break; return; | |
| case 'c': if (ends("ance")) break; | |
| if (ends("ence")) break; return; | |
| case 'e': if (ends("er")) break; return; | |
| case 'i': if (ends("ic")) break; return; | |
| case 'l': if (ends("able")) break; | |
| if (ends("ible")) break; return; | |
| case 'n': if (ends("ant")) break; | |
| if (ends("ement")) break; | |
| if (ends("ment")) break; | |
| /* element etc. not stripped before the m */ | |
| if (ends("ent")) break; return; | |
| case 'o': if (ends("ion") && j >= 0 && (b[j] == 's' || b[j] == 't')) break; | |
| /* j >= 0 fixes Bug 2 */ | |
| if (ends("ou")) break; return; | |
| /* takes care of -ous */ | |
| case 's': if (ends("ism")) break; return; | |
| case 't': if (ends("ate")) break; | |
| if (ends("iti")) break; return; | |
| case 'u': if (ends("ous")) break; return; | |
| case 'v': if (ends("ive")) break; return; | |
| case 'z': if (ends("ize")) break; return; | |
| default: return; | |
| } | |
| if (m() > 1) k = j; | |
| } | |
| /* step6() removes a final -e if m() > 1. */ | |
| private final void step6() | |
| { j = k; | |
| if (b[k] == 'e') | |
| { int a = m(); | |
| if (a > 1 || a == 1 && !cvc(k-1)) k--; | |
| } | |
| if (b[k] == 'l' && doublec(k) && m() > 1) k--; | |
| } | |
| /** Stem the word placed into the Stemmer buffer through calls to add(). | |
| * Returns true if the stemming process resulted in a word different | |
| * from the input. You can retrieve the result with | |
| * getResultLength()/getResultBuffer() or toString(). | |
| */ | |
| public void stem() | |
| { k = i - 1; | |
| if (k > 1) { step1(); step2(); step3(); step4(); step5(); step6(); } | |
| i_end = k+1; i = 0; | |
| } | |
| public static String get_stem(String string) { | |
| String stem_string = ""; | |
| char[] w = new char[501]; | |
| int j = 0; | |
| PorterStemmer s = new PorterStemmer(); | |
| for (char ch : string.toCharArray()) { | |
| if (Character.isLetter((char) ch)) { | |
| ch = Character.toLowerCase((char) ch); | |
| w[j] = (char) ch; | |
| if (j < 500) j++; | |
| if (!Character.isLetter((char) ch)) { | |
| for (int c = 0; c < j; c++) s.add(w[c]); | |
| s.stem(); | |
| stem_string = s.toString(); | |
| break; | |
| } | |
| } | |
| } | |
| if (stem_string.equals("")) { | |
| for (int c = 0; c < j; c++) s.add(w[c]); | |
| s.stem(); | |
| stem_string = s.toString(); | |
| } | |
| return stem_string; | |
| } | |
| public static void main(String[] args) { | |
| if (args.length == 1) { | |
| System.out.println("stem is: "+get_stem(args[0])); | |
| } | |
| else { | |
| System.out.println("Usage: java GeneralScripts.PorterStemmer <word>"); | |
| System.exit(1); | |
| } | |
| } | |
| } | |