"""
The original Metaphone algorithm was published in 1990 as an improvement over
the Soundex algorithm. Like Soundex, it was limited to English-only use. The
Metaphone algorithm does not produce phonetic representations of an input word
or name; rather, the output is an intentionally approximate phonetic
representation. The approximate encoding is necessary to account for the way
speakers vary their pronunciations and misspell or otherwise vary words and
names they are trying to spell.
The Double Metaphone phonetic encoding algorithm is the second generation of
the Metaphone algorithm. Its implementation was described in the June 2000
issue of C/C++ Users Journal. It makes a number of fundamental design
improvements over the original Metaphone algorithm.
It is called "Double" because it can return both a primary and a secondary code
for a string; this accounts for some ambiguous cases as well as for multiple
variants of surnames with common ancestry. For example, encoding the name
"Smith" yields a primary code of SM0 and a secondary code of XMT, while the
name "Schmidt" yields a primary code of XMT and a secondary code of SMT--both
have XMT in common.
Double Metaphone tries to account for myriad irregularities in English of
Slavic, Germanic, Celtic, Greek, French, Italian, Spanish, Chinese, and other
origin. Thus it uses a much more complex ruleset for coding than its
predecessor; for example, it tests for approximately 100 different contexts of
the use of the letter C alone.
This script implements the Double Metaphone algorithm (c) 1998, 1999 originally
implemented by Lawrence Philips in C++. It was further modified in C++ by Kevin
Atkinson (http://aspell.net/metaphone/). It was translated to C by Maurice
Aubrey <maurice@hevanet.com> for use in a Perl extension. A Python version was
created by Andrew Collins on January 12, 2007, using the C source
(http://www.atomodo.com/code/double-metaphone/metaphone.py/view).
Updated 2007-02-14 - Found a typo in the 'gh' section (0.1.1)
Updated 2007-12-17 - Bugs fixed in 'S', 'Z', and 'J' sections (0.2;
Chris Leong)
Updated 2009-03-05 - Various bug fixes against the reference C++
implementation (0.3; Matthew Somerville)
Updated 2012-07 - Fixed long lines, added more docs, changed names,
reformulated as objects, fixed a bug in 'G'
(0.4; Duncan McGreggor)
Updated 2013-06 - Enforced unicode literals (0.5; Ian Beaver)
"""
from __future__ import unicode_literals
from ..utils import check_str, check_empty
from .phonetic_algorithm import PhoneticAlgorithm
VOWELS = ['A', 'E', 'I', 'O', 'U', 'Y']
SILENT_STARTERS = ["GN", "KN", "PN", "WR", "PS"]
class DoubleMetaphone(PhoneticAlgorithm):
def __init__(self):
super().__init__()
def phonetics(self, word : str) -> str | None:
check_str(word)
check_empty(word)
st = word
"""dm(string) -> (string, string or None)
returns the double metaphone codes for given string - always a tuple
there are no checks done on the input string, but it should be a single word or name."""
vowels = ['A', 'E', 'I', 'O', 'U', 'Y']
#st = st.decode('utf-8', 'ignore')
st = st.upper() # st is short for string. I usually prefer descriptive over short, but this var is used a lot!
is_slavo_germanic = (st.find('W') > -1 or st.find('K') > -1 or st.find('CZ') > -1 or st.find('WITZ') > -1)
length = len(st)
first = 2
st = ('-') * first + st + (' ' * 5) # so we can index beyond the begining and end of the input string
last = first + length -1
pos = first # pos is short for position
pri = sec = '' # primary and secondary metaphone codes
#skip these silent letters when at start of word
if st[first:first+2] in ["GN", "KN", "PN", "WR", "PS"] :
pos += 1
# Initial 'X' is pronounced 'Z' e.g. 'Xavier'
if st[first] == 'X' :
pri = sec = 'S' #'Z' maps to 'S'
pos += 1
# main loop through chars in st
while pos <= last :
#print str(pos) + '\t' + st[pos]
ch = st[pos] # ch is short for character
# nxt (short for next characters in metaphone code) is set to a tuple of the next characters in
# the primary and secondary codes and how many characters to move forward in the string.
# the secondary code letter is given only when it is different than the primary.
# This is just a trick to make the code easier to write and read.
nxt = (None, 1) # default action is to add nothing and move to next char
if ch in vowels :
nxt = (None, 1)
if pos == first : # all init vowels now map to 'A'
nxt = ('A', 1)
elif ch == 'B' :
#"-mb", e.g", "dumb", already skipped over... see 'M' below
if st[pos+1] == 'B' :
nxt = ('P', 2)
else :
nxt = ('P', 1)
elif ch == 'C' :
# various germanic
if (pos > (first + 1) and st[pos-2] not in vowels and st[pos-1:pos+2] == 'ACH' and \
(st[pos+2] not in ['I', 'E'] or st[pos-2:pos+4] in ['BACHER', 'MACHER'])) :
nxt = ('K', 2)
# special case 'CAESAR'
elif pos == first and st[first:first+6] == 'CAESAR' :
nxt = ('S', 2)
elif st[pos:pos+4] == 'CHIA' : #italian 'chianti'
nxt = ('K', 2)
elif st[pos:pos+2] == 'CH' :
# find 'michael'
if pos > first and st[pos:pos+4] == 'CHAE' :
nxt = ('K', 'X', 2)
elif pos == first and (st[pos+1:pos+6] in ['HARAC', 'HARIS'] or \
st[pos+1:pos+4] in ["HOR", "HYM", "HIA", "HEM"]) and st[first:first+5] != 'CHORE' :
nxt = ('K', 2)
#germanic, greek, or otherwise 'ch' for 'kh' sound
elif st[first:first+4] in ['VAN ', 'VON '] or st[first:first+3] == 'SCH' \
or st[pos-2:pos+4] in ["ORCHES", "ARCHIT", "ORCHID"] \
or st[pos+2] in ['T', 'S'] \
or ((st[pos-1] in ["A", "O", "U", "E"] or pos == first) \
and st[pos+2] in ["L", "R", "N", "M", "B", "H", "F", "V", "W", " "]) :
nxt = ('K', 1)
else :
if pos > first :
if st[first:first+2] == 'MC' :
nxt = ('K', 2)
else :
nxt = ('X', 'K', 2)
else :
nxt = ('X', 2)
#e.g, 'czerny'
elif st[pos:pos+2] == 'CZ' and st[pos-2:pos+2] != 'WICZ' :
nxt = ('S', 'X', 2)
#e.g., 'focaccia'
elif st[pos+1:pos+4] == 'CIA' :
nxt = ('X', 3)
#double 'C', but not if e.g. 'McClellan'
elif st[pos:pos+2] == 'CC' and not (pos == (first +1) and st[first] == 'M') :
#'bellocchio' but not 'bacchus'
if st[pos+2] in ["I", "E", "H"] and st[pos+2:pos+4] != 'HU' :
#'accident', 'accede' 'succeed'
if (pos == (first +1) and st[first] == 'A') or \
st[pos-1:pos+4] in ['UCCEE', 'UCCES'] :
nxt = ('KS', 3)
#'bacci', 'bertucci', other italian
else:
nxt = ('X', 3)
else :
nxt = ('K', 2)
elif st[pos:pos+2] in ["CK", "CG", "CQ"] :
nxt = ('K', 'K', 2)
elif st[pos:pos+2] in ["CI", "CE", "CY"] :
#italian vs. english
if st[pos:pos+3] in ["CIO", "CIE", "CIA"] :
nxt = ('S', 'X', 2)
else :
nxt = ('S', 2)
else :
#name sent in 'mac caffrey', 'mac gregor
if st[pos+1:pos+3] in [" C", " Q", " G"] :
nxt = ('K', 3)
else :
if st[pos+1] in ["C", "K", "Q"] and st[pos+1:pos+3] not in ["CE", "CI"] :
nxt = ('K', 2)
else : # default for 'C'
nxt = ('K', 1)
elif ch == u'Ç' :
nxt = ('S', 1)
elif ch == 'D' :
if st[pos:pos+2] == 'DG' :
if st[pos+2] in ['I', 'E', 'Y'] : #e.g. 'edge'
nxt = ('J', 3)
else :
nxt = ('TK', 2)
elif st[pos:pos+2] in ['DT', 'DD'] :
nxt = ('T', 2)
else :
nxt = ('T', 1)
elif ch == 'F' :
if st[pos+1] == 'F' :
nxt = ('F', 2)
else :
nxt = ('F', 1)
elif ch == 'G' :
if st[pos+1] == 'H' :
if pos > first and st[pos-1] not in vowels :
nxt = ('K', 2)
elif pos < (first + 3) :
if pos == first : #'ghislane', ghiradelli
if st[pos+2] == 'I' :
nxt = ('J', 2)
else :
nxt = ('K', 2)
#Parker's rule (with some further refinements) - e.g., 'hugh'
elif (pos > (first + 1) and st[pos-2] in ['B', 'H', 'D'] ) \
or (pos > (first + 2) and st[pos-3] in ['B', 'H', 'D'] ) \
or (pos > (first + 3) and st[pos-4] in ['B', 'H'] ) :
nxt = (None, 2)
else :
# e.g., 'laugh', 'McLaughlin', 'cough', 'gough', 'rough', 'tough'
if pos > (first + 2) and st[pos-1] == 'U' \
and st[pos-3] in ["C", "G", "L", "R", "T"] :
nxt = ('F', 2)
else :
if pos > first and st[pos-1] != 'I' :
nxt = ('K', 2)
elif st[pos+1] == 'N' :
if pos == (first +1) and st[first] in vowels and not is_slavo_germanic :
nxt = ('KN', 'N', 2)
else :
# not e.g. 'cagney'
if st[pos+2:pos+4] != 'EY' and st[pos+1] != 'Y' and not is_slavo_germanic :
nxt = ('N', 'KN', 2)
else :
nxt = ('KN', 2)
# 'tagliaro'
elif st[pos+1:pos+3] == 'LI' and not is_slavo_germanic :
nxt = ('KL', 'L', 2)
# -ges-,-gep-,-gel-, -gie- at beginning
elif pos == first and (st[pos+1] == 'Y' \
or st[pos+1:pos+3] in ["ES", "EP", "EB", "EL", "EY", "IB", "IL", "IN", "IE", "EI", "ER"]) :
nxt = ('K', 'J', 2)
# -ger-, -gy-
elif (st[pos+1:pos+2] == 'ER' or st[pos+1] == 'Y') \
and st[first:first+6] not in ["DANGER", "RANGER", "MANGER"] \
and st[pos-1] not in ['E', 'I'] and st[pos-1:pos+2] not in ['RGY', 'OGY'] :
nxt = ('K', 'J', 2)
# italian e.g, 'biaggi'
elif st[pos+1] in ['E', 'I', 'Y'] or st[pos-1:pos+3] in ["AGGI", "OGGI"] :
# obvious germanic
if st[first:first+4] in ['VON ', 'VAN '] or st[first:first+3] == 'SCH' \
or st[pos+1:pos+3] == 'ET' :
nxt = ('K', 2)
else :
# always soft if french ending
if st[pos+1:pos+5] == 'IER ' :
nxt = ('J', 2)
else :
nxt = ('J', 'K', 2)
elif st[pos+1] == 'G' :
nxt = ('K', 2)
else :
nxt = ('K', 1)
elif ch == 'H' :
# only keep if first & before vowel or btw. 2 vowels
if (pos == first or st[pos-1] in vowels) and st[pos+1] in vowels :
nxt = ('H', 2)
else : # (also takes care of 'HH')
nxt = (None, 1)
elif ch == 'J' :
# obvious spanish, 'jose', 'san jacinto'
if st[pos:pos+4] == 'JOSE' or st[first:first+4] == 'SAN ' :
if (pos == first and st[pos+4] == ' ') or st[first:first+4] == 'SAN ' :
nxt = ('H',)
else :
nxt = ('J', 'H')
elif pos == first and st[pos:pos+4] != 'JOSE' :
nxt = ('J', 'A') # Yankelovich/Jankelowicz
else :
# spanish pron. of e.g. 'bajador'
if st[pos-1] in vowels and not is_slavo_germanic \
and st[pos+1] in ['A', 'O'] :
nxt = ('J', 'H')
else :
if pos == last :
nxt = ('J', ' ')
else :
if st[pos+1] not in ["L", "T", "K", "S", "N", "M", "B", "Z"] \
and st[pos-1] not in ["S", "K", "L"] :
nxt = ('J',)
else :
nxt = (None, )
if st[pos+1] == 'J' :
nxt = nxt + (2,)
else :
nxt = nxt + (1,)
elif ch == 'K' :
if st[pos+1] == 'K' :
nxt = ('K', 2)
else :
nxt = ('K', 1)
elif ch == 'L' :
if st[pos+1] == 'L' :
# spanish e.g. 'cabrillo', 'gallegos'
if (pos == (last - 2) and st[pos-1:pos+3] in ["ILLO", "ILLA", "ALLE"]) \
or ((st[last-1:last+1] in ["AS", "OS"] or st[last] in ["A", "O"]) \
and st[pos-1:pos+3] == 'ALLE') :
nxt = ('L', '', 2)
else :
nxt = ('L', 2)
else :
nxt = ('L', 1)
elif ch == 'M' :
if st[pos+1:pos+4] == 'UMB' \
and (pos + 1 == last or st[pos+2:pos+4] == 'ER') \
or st[pos+1] == 'M' :
nxt = ('M', 2)
else :
nxt = ('M', 1)
elif ch == 'N' :
if st[pos+1] == 'N' :
nxt = ('N', 2)
else :
nxt = ('N', 1)
elif ch == u'Ñ' :
nxt = ('N', 1)
elif ch == 'P' :
if st[pos+1] == 'H' :
nxt = ('F', 2)
elif st[pos+1] in ['P', 'B'] : # also account for "campbell", "raspberry"
nxt = ('P', 2)
else :
nxt = ('P', 1)
elif ch == 'Q' :
if st[pos+1] == 'Q' :
nxt = ('K', 2)
else :
nxt = ('K', 1)
elif ch == 'R' :
# french e.g. 'rogier', but exclude 'hochmeier'
if pos == last and not is_slavo_germanic \
and st[pos-2:pos] == 'IE' and st[pos-4:pos-2] not in ['ME', 'MA'] :
nxt = ('', 'R')
else :
nxt = ('R',)
if st[pos+1] == 'R' :
nxt = nxt + (2,)
else :
nxt = nxt + (1,)
elif ch == 'S' :
# special cases 'island', 'isle', 'carlisle', 'carlysle'
if st[pos-1:pos+2] in ['ISL', 'YSL'] :
nxt = (None, 1)
# special case 'sugar-'
elif pos == first and st[first:first+5] == 'SUGAR' :
nxt =('X', 'S', 1)
elif st[pos:pos+2] == 'SH' :
# germanic
if st[pos+1:pos+5] in ["HEIM", "HOEK", "HOLM", "HOLZ"] :
nxt = ('S', 2)
else :
nxt = ('X', 2)
# italian & armenian
elif st[pos:pos+3] in ["SIO", "SIA"] or st[pos:pos+4] == 'SIAN' :
if not is_slavo_germanic :
nxt = ('S', 'X', 3)
else :
nxt = ('S', 3)
# german & anglicisations, e.g. 'smith' match 'schmidt', 'snider' match 'schneider'
# also, -sz- in slavic language altho in hungarian it is pronounced 's'
elif (pos == first and st[pos+1] in ["M", "N", "L", "W"]) or st[pos+1] == 'Z' :
nxt = ('S', 'X')
if st[pos+1] == 'Z' :
nxt = nxt + (2,)
else :
nxt = nxt + (1,)
elif st[pos:pos+2] == 'SC' :
# Schlesinger's rule
if st[pos+2] == 'H' :
# dutch origin, e.g. 'school', 'schooner'
if st[pos+3:pos+5] in ["OO", "ER", "EN", "UY", "ED", "EM"] :
# 'schermerhorn', 'schenker'
if st[pos+3:pos+5] in ['ER', 'EN'] :
nxt = ('X', 'SK', 3)
else :
nxt = ('SK', 3)
else :
if pos == first and st[first+3] not in vowels and st[first+3] != 'W' :
nxt = ('X', 'S', 3)
else :
nxt = ('X', 3)
elif st[pos+2] in ['I', 'E', 'Y'] :
nxt = ('S', 3)
else :
nxt = ('SK', 3)
# french e.g. 'resnais', 'artois'
elif pos == last and st[pos-2:pos] in ['AI', 'OI'] :
nxt = ('', 'S', 1)
else :
nxt = ('S',)
if st[pos+1] in ['S', 'Z'] :
nxt = nxt + (2,)
else :
nxt = nxt + (1,)
elif ch == 'T' :
if st[pos:pos+4] == 'TION' :
nxt = ('X', 3)
elif st[pos:pos+3] in ['TIA', 'TCH'] :
nxt = ('X', 3)
elif st[pos:pos+2] == 'TH' or st[pos:pos+3] == 'TTH' :
# special case 'thomas', 'thames' or germanic
if st[pos+2:pos+4] in ['OM', 'AM'] or st[first:first+4] in ['VON ', 'VAN '] \
or st[first:first+3] == 'SCH' :
nxt = ('T', 2)
else :
nxt = ('0', 'T', 2)
elif st[pos+1] in ['T', 'D'] :
nxt = ('T', 2)
else :
nxt = ('T', 1)
elif ch == 'V' :
if st[pos+1] == 'V' :
nxt = ('F', 2)
else :
nxt = ('F', 1)
elif ch == 'W' :
# can also be in middle of word
if st[pos:pos+2] == 'WR' :
nxt = ('R', 2)
elif pos == first and (st[pos+1] in vowels or st[pos:pos+2] == 'WH') :
# Wasserman should match Vasserman
if st[pos+1] in vowels :
nxt = ('A', 'F', 1)
else :
nxt = ('A', 1)
# Arnow should match Arnoff
elif (pos == last and st[pos-1] in vowels) \
or st[pos-1:pos+5] in ["EWSKI", "EWSKY", "OWSKI", "OWSKY"] \
or st[first:first+3] == 'SCH' :
nxt = ('', 'F', 1)
# polish e.g. 'filipowicz'
elif st[pos:pos+4] in ["WICZ", "WITZ"] :
nxt = ('TS', 'FX', 4)
else : # default is to skip it
nxt = (None, 1)
elif ch == 'X' :
# french e.g. breaux
nxt = (None,)
if not(pos == last and (st[pos-3:pos] in ["IAU", "EAU"] \
or st[pos-2:pos] in ['AU', 'OU'])):
nxt = ('KS',)
if st[pos+1] in ['C', 'X'] :
nxt = nxt + (2,)
else :
nxt = nxt + (1,)
elif ch == 'Z' :
# chinese pinyin e.g. 'zhao'
if st[pos+1] == 'H' :
nxt = ('J',)
elif st[pos+1:pos+3] in ["ZO", "ZI", "ZA"] \
or (is_slavo_germanic and pos > first and st[pos-1] != 'T') :
nxt = ('S', 'TS')
else :
nxt = ('S',)
if st[pos+1] == 'Z' :
nxt = nxt + (2,)
else :
nxt = nxt + (1,)
# ----------------------------------
# --- end checking letters------
# ----------------------------------
#print str(nxt)
if len(nxt) == 2 :
if nxt[0] :
pri += nxt[0]
sec += nxt[0]
pos += nxt[1]
elif len(nxt) == 3 :
if nxt[0] :
pri += nxt[0]
if nxt[1] :
sec += nxt[1]
pos += nxt[2]
return pri, sec if pri != sec else None