197 lines
4.8 KiB
Python
197 lines
4.8 KiB
Python
#!/usr/bin/python2
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# Copyright 2003-2008, Nick Mathewson. See LICENSE for licensing info.
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"""metaphone.py -- Pure-python metaphone implementation.
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(This is not guaranteed to match the real metaphone algorithm; I
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haven't tested it thorougly enough. Let me know if you find bugs.
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Based on the original C++ metaphone implementation.)
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"""
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from __future__ import print_function
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from six.moves import map
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from six.moves import range
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TRIPLES = {
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'dge': 'j',
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'dgi': 'j',
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'dgy': 'j',
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'sia': '+x',
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'sio': '+x',
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'tia': '+x',
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'tio': '+x',
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'tch': '',
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'tha': '0',
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'the': '0',
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'thi': '0',
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'tho': '0',
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'thu': '0',
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}
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DOUBLES = {
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'ph' : 'f',
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'sh' : 'x'
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}
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SINGLETONS = {
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'd': 't',
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'f': 'f',
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'j': 'j',
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'l': 'l',
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'm': 'm',
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'n': 'n',
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'r': 'r',
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'p': 'p',
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'q': 'k',
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'v': 'f',
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'x': 'ks',
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'z': 's',
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}
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ALLCHARS = "".join(map(chr, list(range(256))))
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NONLCCHARS = "".join([c for c in ALLCHARS if not c.islower()])
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def metaphone(s):
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"""Return the metaphone equivalent of a provided string"""
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s = s.lower()
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s = s.translate(ALLCHARS, NONLCCHARS)
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if not s: return ""
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# If ae, gn, kn, pn, wr then drop the first letter.
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if s[:2] in ("ae", "gn", "kn", "pn", "wr"):
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s = s[1:]
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# Change "x" to "s"
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if s[0] == 'x':
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s = "s%s" % s[1:]
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# Get rid of "h" in "wh".
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if s[:2] == 'wh':
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s = "w%s" % s[1:]
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# Get rid of s from end.
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if s[-1] == 's':
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s = s[:-1]
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result = []
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prevLtr = ' '
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vowelBefore = 0
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lastChar = len(s)-1
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for idx in range(len(s)):
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curLtr = s[idx]
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# If first char is a vowel, keep it.
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if curLtr in "aeiou":
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if idx == 0:
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result.append(curLtr)
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continue
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# Skip double letters.
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if idx < lastChar:
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if curLtr == s[idx+1]:
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continue
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try:
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r = TRIPLES[s[idx:idx+3]]
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if r == "+x":
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if idx > 1:
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result.append("x")
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continue
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else:
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result.append(r)
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continue
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except KeyError:
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pass
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try:
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r = DOUBLES[s[idx:idx+2]]
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result.append(r)
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continue
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except KeyError:
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pass
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try:
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r = SINGLETONS[s[idx]]
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result.append(r)
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continue
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except KeyError:
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pass
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if idx > 0:
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prevLtr = s[idx-1]
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vowelBefore = prevLtr in "aeiou"
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curLtr = s[idx]
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nextLtr2 = ' '
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if idx < lastChar:
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nextLtr = s[idx+1]
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vowelAfter = nextLtr in "aeiou"
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frontvAfter = nextLtr in "eiy"
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if idx+1 < lastChar:
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nextLtr2 = s[idx+2]
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else:
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nextLtr = ' '
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vowelAfter = frontvAfter = 0
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if curLtr == 'b':
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if idx == lastChar and prevLtr == 'm':
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pass
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else:
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result.append(curLtr)
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elif curLtr == 'c':
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# silent 'sci', 'sce, 'scy', 'sci', etc OK.
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if not (prevLtr == 's' and frontvAfter):
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if nextLtr in 'ia':
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result.append("x")
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elif frontvAfter:
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result.append("s")
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elif prevLtr == 's' and nextLtr == 'h':
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result.append('k')
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elif nextLtr == 'h':
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if idx == 0 and nextLtr2 in "aeiou":
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result.append('k')
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else:
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result.append('x')
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elif prevLtr == 'c':
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result.append('c')
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else:
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result.append('k')
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elif curLtr == 'g':
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if (idx < lastChar-1) and nextLtr == 'h':
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pass
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elif s[idx:] == 'gned':
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pass
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elif s[idx:] == 'gn':
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pass
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elif prevLtr == 'd' and frontvAfter:
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pass
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else:
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hard = (prevLtr == 'g')
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if frontvAfter and not hard:
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result.append('j')
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else:
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result.append('k')
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elif curLtr == 'h':
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if prevLtr in 'csptg':
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pass
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elif vowelBefore and not vowelAfter:
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pass
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else:
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result.append('h')
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elif curLtr == 'k':
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if prevLtr != 'c': result.append('k')
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elif curLtr in 'wy':
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if vowelAfter:
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result.append(curLtr)
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return "".join(result)
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def demo(a):
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print(a, "=>", metaphone(a))
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if __name__ == '__main__':
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demo("Nick. Mathewson")
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demo("joe schmidt")
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demo("Beethoven")
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demo("Because the world is round")
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