soundex.py源代码分析

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"""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 ([email protected])"

__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())