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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