soundex.py源代码分析

 

"""Soundex algorithm

 

This program is part of "Dive Into Python", a free Python book for

experienced programmers.  Visit http://diveintopython.org/ for the

latest version.

"""

 

__author__ = "Mark Pilgrim ([e-mail])"

__version__ = "$Revision: 1.5 $"

__date__ = "$Date: 2004/05/11 19:11:21 $"

__copyright__ = "Copyright (c) 2004 Mark Pilgrim"

__license__ = "Python"

 

import string

 

allChar = string.uppercase + string.lowercase

charToSoundex = string.maketrans(allChar, "91239129922455912623919292" * 2)

 

def soundex(source):

    "convert string to Soundex equivalent"

 

    # Soundex requirements:

    # source string must be at least 1 character

    # and must consist entirely of letters

    if (not source) or (not source.isalpha()):

        return "0000"

 

    # Soundex algorithm:

    # 1. make first character uppercase

    # 2. translate all other characters to Soundex digits

    digits = source[0].upper() + source[1:].translate(charToSoundex)

 

    # 3. remove consecutive duplicates

    digits2 = digits[0]

    for d in digits[1:]:

        if digits2[-1] != d:

            digits2 += d

 

    # 4. remove all "9"s

    # 5. pad end with "0"s to 4 characters

    return (digits2.replace('9', '') + '000')[:4]

 

if __name__ == '__main__':

    import sys

    if sys.argv[1:]:

        print soundex(sys.argv[1])

    else:

        from timeit import Timer

        names = ('Woo', 'Pilgrim', 'Flingjingwaller')

        for name in names:

            statement = "soundex('%s')" % name

            t = Timer(statement, "from __main__ import soundex")

            print name.ljust(15), soundex(name), min(t.repeat())