org.terrier.terms

Class PorterStemmer

java.lang.Object

org.terrier.terms.StemmerTermPipeline

org.terrier.terms.PorterStemmer

All Implemented Interfaces:

Stemmer, TermPipeline

Direct Known Subclasses:

WeakPorterStemmer

public class PorterStemmer
extends StemmerTermPipeline

Stemmer, implementing the Porter Stemming Algorithm. By Martin Porter. 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.

Since:

3.0

Field Summary

Fields

Modifier and Type	Field and Description
protected char[]	b
protected int	i
protected int	i_end
protected static int	INC
protected int	j
protected int	k

Fields inherited from class org.terrier.terms.StemmerTermPipeline

next

Constructor Summary

Constructors

Constructor and Description
PorterStemmer() constructor
PorterStemmer(TermPipeline next) Constructs an instance of PorterStemmer.

Method Summary

Methods

Modifier and Type	Method and Description
void	add(char ch) Add a character to the word being stemmed.
void	add(char[] w, int wLen) Adds wLen characters to the word being stemmed contained in a portion of a char[] array.
protected boolean	cons(int _i)
protected boolean	cvc(int _i)
protected boolean	doublec(int _j)
protected boolean	ends(String s)
char[]	getResultBuffer() Returns a reference to a character buffer containing the results of the stemming process.
int	getResultLength() Returns the length of the word resulting from the stemming process.
protected int	m()
static void	main(String[] args) Test program for demonstrating the Stemmer.
protected void	r(String s)
protected void	setto(String s)
void	stem() Stem the word placed into the Stemmer buffer through calls to add().
String	stem(String s) Returns the stem of a given term
protected void	step1()
protected void	step2()
protected void	step3()
protected void	step4()
protected void	step5()
protected void	step6()
String	toString() 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.)
protected boolean	vowelinstem()

Methods inherited from class org.terrier.terms.StemmerTermPipeline

processTerm, reset

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail

b

protected char[] b

i

protected int i

i_end

protected int i_end

j

protected int j

k

protected int k

INC

protected static final int INC

See Also:

Constant Field Values

Constructor Detail

PorterStemmer

public PorterStemmer()

constructor

PorterStemmer

public PorterStemmer(TermPipeline next)

Constructs an instance of PorterStemmer.

Parameters:

next -

Method Detail

add

public void add(char ch)

Add a character to the word being stemmed. When you are finished adding characters, you can call stem(void) to stem the word.

add

public void add(char[] w,
       int wLen)

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.

toString

public String toString()

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.)

Overrides:

toString in class Object

getResultLength

public int getResultLength()

Returns the length of the word resulting from the stemming process.

getResultBuffer

public char[] getResultBuffer()

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.

cons

protected final boolean cons(int _i)

m

protected final int m()

vowelinstem

protected final boolean vowelinstem()

doublec

protected final boolean doublec(int _j)

cvc

protected final boolean cvc(int _i)

ends

protected final boolean ends(String s)

setto

protected final void setto(String s)

r

protected final void r(String s)

step1

protected final void step1()

step2

protected final void step2()

step3

protected final void step3()

step4

protected final void step4()

step5

protected final void step5()

step6

protected final void step6()

stem

public void stem()

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().

main

public static void main(String[] args)

Test program for demonstrating the Stemmer. It reads text from a a list of files, stems each word, and writes the result to standard output. Note that the word stemmed is expected to be in lower case: forcing lower case must be done outside the Stemmer class. Usage: Stemmer file-name file-name ...

stem

public String stem(String s)

Returns the stem of a given term

Parameters:

s - String the term to be stemmed.

Returns:

String the stem of a given term.