Snowball stemming library collection for Python

This document pertains to the Python version of the stemmer library distribution, available for download from:

• https://github.com/shibukawa/snowball/

  This repository includes Python source code generator

• https://github.com/shibukawa/snowball_python/

  This repository includes generated Python source codes

Original program is maintained at following place:

• http://snowball.tartarus.org/

Original Snowball product created by Dr Martin Porter and Richard Boulton (Java porting). Original Snowball and my products are released under BSD license.

How to use library

The snowballstemmer module has two functions.

The snowballstemmer.algorithms function returns a list of avilable algorithm name' string.

The snowballstemmer.stemmer function accepts algorithm name and returns Stemmer objects.

Stemmer objects have Stemmer.stemWord(word) method and Stemmer.stemWords(word[]) method.

.. code-block:: python

import snowballstemmer

stemmer = snowballstemmer.stemmer('english'); print(stemmer.stemWords("We are the world".split()));

Stemmer objects have Stemmer.maxCacheSize property. They cache result within the value. Default is 10000.

Accerarates Stemming

if PyStemmer is installed, snowballstemmer.stemmer returns PyStemmer\ 's Stemmer objects. This Stemmer object has same methods (Stemmer.stemWord(), Stemmer.stemWords()).

PyStemmer is a Snowball's libstemmer_c wrapper module and it returns 100% compatible result with snowballstemmer.

PyStemmer has faster speed because it uses C-lang module, and snowballstemmer has higher usability because it is pure Python module.

• PyStemmer <http://pypi.python.org/pypi/PyStemmer/>_

Benchmark

Test Case: Snowball stemmer check data (16 algorithms, total 582560 words, cache hit 0%)
Computer: MacBook Pro 3rd Gen Corei7 2.3GHz

* Python 2.7 + **snowballstemmer** : 2m 30s
* PyPy 1.9 + **snowballstemmer** : 45s
* Python 2.7 + **PyStemmer** : 5s

This test case is much harder than usual usecases!

The TestApp example
-------------------

The ``testapp.py`` example program allows you to run any of the stemmers
on a sample vocabulary.

Usage::

   testapp.py <algorithm> "sentences ... "

.. code-block:: bash

   $ python testapp.py English "sentences... "

Thanks
-------

* Original Snowball authors
* Emil Stenström

License
-------

It is a BSD licensed library.

-----------------------------

Copyright (c) 2013, Yoshiki Shibukawa

All rights reserved.

Redistribution and use in source and binary forms, with or without modification, are permitted provided
that the following conditions are met:

* Redistributions of source code must retain the above copyright notice, this list of conditions and
  the following disclaimer.
* Redistributions in binary form must reproduce the above copyright notice, this list of conditions
  and the following disclaimer in the documentation and/or other materials provided with the distribution.

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