abydos.phonetic.metaphone.double_metaphone()

Complexity

Conditions

219

Size

Total Lines	719
Code Lines	492

Duplication

Lines	0
Ratio	0 %

Importance

Changes

0

# -*- coding: utf-8 -*-
def double_metaphone(word, max_length=-1):
    """Return the Double Metaphone code for a word.

    Based on Lawrence Philips' (Visual) C++ code from 1999
    :cite:`Philips:2000`.

    :param word: the word to transform
    :param max_length: the maximum length of the returned Double Metaphone
        codes (defaults to 64, but in Philips' original implementation this
        was 4)
    :returns: the Double Metaphone value(s)
    :rtype: tuple

    >>> double_metaphone('Christopher')
    ('KRSTFR', '')
    >>> double_metaphone('Niall')
    ('NL', '')
    >>> double_metaphone('Smith')
    ('SM0', 'XMT')
    >>> double_metaphone('Schmidt')
    ('XMT', 'SMT')
    """
    # Require a max_length of at least 4
    if max_length != -1:
        max_length = max(4, max_length)
    else:
        max_length = 64

    primary = ''
    secondary = ''

    def _slavo_germanic():
        """Return True if the word appears to be Slavic or Germanic."""
        if 'W' in word or 'K' in word or 'CZ' in word:
            return True
        return False

    def _metaph_add(pri, sec=''):
        """Return a new metaphone tuple with the supplied elements."""
        newpri = primary
        newsec = secondary
        if pri:
            newpri += pri
        if sec:
            if sec != ' ':
                newsec += sec
        else:
            newsec += pri
        return newpri, newsec

    def _is_vowel(pos):
        """Return True if the character at word[pos] is a vowel."""
        if pos >= 0 and word[pos] in {'A', 'E', 'I', 'O', 'U', 'Y'}:
            return True
        return False

    def _get_at(pos):
        """Return the character at word[pos]."""
        return word[pos]

    def _string_at(pos, slen, substrings):
        """Return True if word[pos:pos+slen] is in substrings."""
        if pos < 0:
            return False
        return word[pos:pos+slen] in substrings

    current = 0
    length = len(word)
    if length < 1:
        return '', ''
    last = length - 1

    word = word.upper()
    word = word.replace('ß', 'SS')

    # Pad the original string so that we can index beyond the edge of the world
    word += '     '

    # Skip these when at start of word
    if word[0:2] in {'GN', 'KN', 'PN', 'WR', 'PS'}:
        current += 1

    # Initial 'X' is pronounced 'Z' e.g. 'Xavier'
    if _get_at(0) == 'X':
        primary, secondary = _metaph_add('S')  # 'Z' maps to 'S'
        current += 1

    # Main loop
    while True:
        if current >= length:
            break

        if _get_at(current) in {'A', 'E', 'I', 'O', 'U', 'Y'}:
            if current == 0:
                # All init vowels now map to 'A'
                primary, secondary = _metaph_add('A')
            current += 1
            continue

        elif _get_at(current) == 'B':
            # "-mb", e.g", "dumb", already skipped over...
            primary, secondary = _metaph_add('P')
            if _get_at(current + 1) == 'B':
                current += 2
            else:
                current += 1
            continue

        elif _get_at(current) == 'Ç':
            primary, secondary = _metaph_add('S')
            current += 1
            continue

        elif _get_at(current) == 'C':
            # Various Germanic
            if (current > 1 and not _is_vowel(current - 2) and
                    _string_at((current - 1), 3, {'ACH'}) and
                    ((_get_at(current + 2) != 'I') and
                     ((_get_at(current + 2) != 'E') or
                      _string_at((current - 2), 6,
                                 {'BACHER', 'MACHER'})))):
                primary, secondary = _metaph_add('K')
                current += 2
                continue

            # Special case 'caesar'
            elif current == 0 and _string_at(current, 6, {'CAESAR'}):
                primary, secondary = _metaph_add('S')
                current += 2
                continue

            # Italian 'chianti'
            elif _string_at(current, 4, {'CHIA'}):
                primary, secondary = _metaph_add('K')
                current += 2
                continue

            elif _string_at(current, 2, {'CH'}):
                # Find 'Michael'
                if current > 0 and _string_at(current, 4, {'CHAE'}):
                    primary, secondary = _metaph_add('K', 'X')
                    current += 2
                    continue

                # Greek roots e.g. 'chemistry', 'chorus'
                elif (current == 0 and
                      (_string_at((current + 1), 5,
                                  {'HARAC', 'HARIS'}) or
                       _string_at((current + 1), 3,
                                  {'HOR', 'HYM', 'HIA', 'HEM'})) and
                      not _string_at(0, 5, {'CHORE'})):
                    primary, secondary = _metaph_add('K')
                    current += 2
                    continue

                # Germanic, Greek, or otherwise 'ch' for 'kh' sound
                elif ((_string_at(0, 4, {'VAN ', 'VON '}) or
                       _string_at(0, 3, {'SCH'})) or
                      # 'architect but not 'arch', 'orchestra', 'orchid'
                      _string_at((current - 2), 6,
                                 {'ORCHES', 'ARCHIT', 'ORCHID'}) or
                      _string_at((current + 2), 1, {'T', 'S'}) or
                      ((_string_at((current - 1), 1,
                                   {'A', 'O', 'U', 'E'}) or
                        (current == 0)) and
                       # e.g., 'wachtler', 'wechsler', but not 'tichner'
                       _string_at((current + 2), 1,
                                  {'L', 'R', 'N', 'M', 'B', 'H', 'F', 'V', 'W',
                                   ' '}))):
                    primary, secondary = _metaph_add('K')

                else:
                    if current > 0:
                        if _string_at(0, 2, {'MC'}):
                            # e.g., "McHugh"
                            primary, secondary = _metaph_add('K')
                        else:
                            primary, secondary = _metaph_add('X', 'K')
                    else:
                        primary, secondary = _metaph_add('X')

                current += 2
                continue

            # e.g, 'czerny'
            elif (_string_at(current, 2, {'CZ'}) and
                  not _string_at((current - 2), 4, {'WICZ'})):
                primary, secondary = _metaph_add('S', 'X')
                current += 2
                continue

            # e.g., 'focaccia'
            elif _string_at((current + 1), 3, {'CIA'}):
                primary, secondary = _metaph_add('X')
                current += 3

            # double 'C', but not if e.g. 'McClellan'
            elif (_string_at(current, 2, {'CC'}) and
                  not ((current == 1) and (_get_at(0) == 'M'))):
                # 'bellocchio' but not 'bacchus'
                if ((_string_at((current + 2), 1,
                                {'I', 'E', 'H'}) and
                     not _string_at((current + 2), 2, ['HU']))):
                    # 'accident', 'accede' 'succeed'
                    if ((((current == 1) and _get_at(current - 1) == 'A') or
                         _string_at((current - 1), 5,
                                    {'UCCEE', 'UCCES'}))):
                        primary, secondary = _metaph_add('KS')
                    # 'bacci', 'bertucci', other italian
                    else:
                        primary, secondary = _metaph_add('X')
                    current += 3
                    continue
                else:  # Pierce's rule
                    primary, secondary = _metaph_add('K')
                    current += 2
                    continue

            elif _string_at(current, 2, {'CK', 'CG', 'CQ'}):
                primary, secondary = _metaph_add('K')
                current += 2
                continue

            elif _string_at(current, 2, {'CI', 'CE', 'CY'}):
                # Italian vs. English
                if _string_at(current, 3, {'CIO', 'CIE', 'CIA'}):
                    primary, secondary = _metaph_add('S', 'X')
                else:
                    primary, secondary = _metaph_add('S')
                current += 2
                continue

            # else
            else:
                primary, secondary = _metaph_add('K')

                # name sent in 'mac caffrey', 'mac gregor
                if _string_at((current + 1), 2, {' C', ' Q', ' G'}):
                    current += 3
                elif (_string_at((current + 1), 1,
                                 {'C', 'K', 'Q'}) and
                      not _string_at((current + 1), 2, {'CE', 'CI'})):
                    current += 2
                else:
                    current += 1
                continue

        elif _get_at(current) == 'D':
            if _string_at(current, 2, {'DG'}):
                if _string_at((current + 2), 1, {'I', 'E', 'Y'}):
                    # e.g. 'edge'
                    primary, secondary = _metaph_add('J')
                    current += 3
                    continue
                else:
                    # e.g. 'edgar'
                    primary, secondary = _metaph_add('TK')
                    current += 2
                    continue

            elif _string_at(current, 2, {'DT', 'DD'}):
                primary, secondary = _metaph_add('T')
                current += 2
                continue

            # else
            else:
                primary, secondary = _metaph_add('T')
                current += 1
                continue

        elif _get_at(current) == 'F':
            if _get_at(current + 1) == 'F':
                current += 2
            else:
                current += 1
            primary, secondary = _metaph_add('F')
            continue

        elif _get_at(current) == 'G':
            if _get_at(current + 1) == 'H':
                if (current > 0) and not _is_vowel(current - 1):
                    primary, secondary = _metaph_add('K')
                    current += 2
                    continue

                # 'ghislane', ghiradelli
                elif current == 0:
                    if _get_at(current + 2) == 'I':
                        primary, secondary = _metaph_add('J')
                    else:
                        primary, secondary = _metaph_add('K')
                    current += 2
                    continue

                # Parker's rule (with some further refinements) - e.g., 'hugh'
                elif (((current > 1) and
                       _string_at((current - 2), 1, {'B', 'H', 'D'})) or
                      # e.g., 'bough'
                      ((current > 2) and
                       _string_at((current - 3), 1, {'B', 'H', 'D'})) or
                      # e.g., 'broughton'
                      ((current > 3) and
                       _string_at((current - 4), 1, {'B', 'H'}))):
                    current += 2
                    continue
                else:
                    # e.g. 'laugh', 'McLaughlin', 'cough',
                    #      'gough', 'rough', 'tough'
                    if ((current > 2) and
                            (_get_at(current - 1) == 'U') and
                            (_string_at((current - 3), 1,
                                        {'C', 'G', 'L', 'R', 'T'}))):
                        primary, secondary = _metaph_add('F')
                    elif (current > 0) and _get_at(current - 1) != 'I':
                        primary, secondary = _metaph_add('K')
                    current += 2
                    continue

            elif _get_at(current + 1) == 'N':
                if (current == 1) and _is_vowel(0) and not _slavo_germanic():
                    primary, secondary = _metaph_add('KN', 'N')
                # not e.g. 'cagney'
                elif (not _string_at((current + 2), 2, {'EY'}) and
                      (_get_at(current + 1) != 'Y') and
                      not _slavo_germanic()):
                    primary, secondary = _metaph_add('N', 'KN')
                else:
                    primary, secondary = _metaph_add('KN')
                current += 2
                continue

            # 'tagliaro'
            elif (_string_at((current + 1), 2, {'LI'}) and
                  not _slavo_germanic()):
                primary, secondary = _metaph_add('KL', 'L')
                current += 2
                continue

            # -ges-, -gep-, -gel-, -gie- at beginning
            elif ((current == 0) and
                  ((_get_at(current + 1) == 'Y') or
                   _string_at((current + 1), 2, {'ES', 'EP', 'EB', 'EL', 'EY',
                                                 'IB', 'IL', 'IN', 'IE', 'EI',
                                                 'ER'}))):
                primary, secondary = _metaph_add('K', 'J')
                current += 2
                continue

            #  -ger-,  -gy-
            elif ((_string_at((current + 1), 2, {'ER'}) or
                   (_get_at(current + 1) == 'Y')) and not
                  _string_at(0, 6, {'DANGER', 'RANGER', 'MANGER'}) and not
                  _string_at((current - 1), 1, {'E', 'I'}) and not
                  _string_at((current - 1), 3, {'RGY', 'OGY'})):
                primary, secondary = _metaph_add('K', 'J')
                current += 2
                continue

            #  italian e.g, 'biaggi'
            elif (_string_at((current + 1), 1, {'E', 'I', 'Y'}) or
                  _string_at((current - 1), 4, {'AGGI', 'OGGI'})):
                # obvious germanic
                if (((_string_at(0, 4, {'VAN ', 'VON '}) or
                      _string_at(0, 3, {'SCH'})) or
                     _string_at((current + 1), 2, {'ET'}))):
                    primary, secondary = _metaph_add('K')
                elif _string_at((current + 1), 4, {'IER '}):
                    primary, secondary = _metaph_add('J')
                else:
                    primary, secondary = _metaph_add('J', 'K')
                current += 2
                continue

            else:
                if _get_at(current + 1) == 'G':
                    current += 2
                else:
                    current += 1
                primary, secondary = _metaph_add('K')
                continue

        elif _get_at(current) == 'H':
            # only keep if first & before vowel or btw. 2 vowels
            if ((((current == 0) or _is_vowel(current - 1)) and
                 _is_vowel(current + 1))):
                primary, secondary = _metaph_add('H')
                current += 2
            else:  # also takes care of 'HH'
                current += 1
            continue

        elif _get_at(current) == 'J':
            # obvious spanish, 'jose', 'san jacinto'
            if _string_at(current, 4, ['JOSE']) or _string_at(0, 4, {'SAN '}):
                if ((((current == 0) and (_get_at(current + 4) == ' ')) or
                     _string_at(0, 4, ['SAN ']))):
                    primary, secondary = _metaph_add('H')
                else:
                    primary, secondary = _metaph_add('J', 'H')
                current += 1
                continue

            elif (current == 0) and not _string_at(current, 4, {'JOSE'}):
                # Yankelovich/Jankelowicz
                primary, secondary = _metaph_add('J', 'A')
            # Spanish pron. of e.g. 'bajador'
            elif (_is_vowel(current - 1) and
                  not _slavo_germanic() and
                  ((_get_at(current + 1) == 'A') or
                   (_get_at(current + 1) == 'O'))):
                primary, secondary = _metaph_add('J', 'H')
            elif current == last:
                primary, secondary = _metaph_add('J', ' ')
            elif (not _string_at((current + 1), 1,
                                 {'L', 'T', 'K', 'S', 'N', 'M', 'B', 'Z'}) and
                  not _string_at((current - 1), 1, {'S', 'K', 'L'})):
                primary, secondary = _metaph_add('J')

            if _get_at(current + 1) == 'J':  # it could happen!
                current += 2
            else:
                current += 1
            continue

        elif _get_at(current) == 'K':
            if _get_at(current + 1) == 'K':
                current += 2
            else:
                current += 1
            primary, secondary = _metaph_add('K')
            continue

        elif _get_at(current) == 'L':
            if _get_at(current + 1) == 'L':
                # Spanish e.g. 'cabrillo', 'gallegos'
                if (((current == (length - 3)) and
                     _string_at((current - 1), 4, {'ILLO', 'ILLA', 'ALLE'})) or
                        ((_string_at((last - 1), 2, {'AS', 'OS'}) or
                          _string_at(last, 1, {'A', 'O'})) and
                         _string_at((current - 1), 4, {'ALLE'}))):
                    primary, secondary = _metaph_add('L', ' ')
                    current += 2
                    continue
                current += 2
            else:
                current += 1
            primary, secondary = _metaph_add('L')
            continue

        elif _get_at(current) == 'M':
            if (((_string_at((current - 1), 3, {'UMB'}) and
                  (((current + 1) == last) or
                   _string_at((current + 2), 2, {'ER'}))) or
                 # 'dumb', 'thumb'
                 (_get_at(current + 1) == 'M'))):
                current += 2
            else:
                current += 1
            primary, secondary = _metaph_add('M')
            continue

        elif _get_at(current) == 'N':
            if _get_at(current + 1) == 'N':
                current += 2
            else:
                current += 1
            primary, secondary = _metaph_add('N')
            continue

        elif _get_at(current) == 'Ñ':
            current += 1
            primary, secondary = _metaph_add('N')
            continue

        elif _get_at(current) == 'P':
            if _get_at(current + 1) == 'H':
                primary, secondary = _metaph_add('F')
                current += 2
                continue

            # also account for "campbell", "raspberry"
            elif _string_at((current + 1), 1, {'P', 'B'}):
                current += 2
            else:
                current += 1
            primary, secondary = _metaph_add('P')
            continue

        elif _get_at(current) == 'Q':
            if _get_at(current + 1) == 'Q':
                current += 2
            else:
                current += 1
            primary, secondary = _metaph_add('K')
            continue

        elif _get_at(current) == 'R':
            # french e.g. 'rogier', but exclude 'hochmeier'
            if (((current == last) and
                 not _slavo_germanic() and
                 _string_at((current - 2), 2, {'IE'}) and
                 not _string_at((current - 4), 2, {'ME', 'MA'}))):
                primary, secondary = _metaph_add('', 'R')
            else:
                primary, secondary = _metaph_add('R')

            if _get_at(current + 1) == 'R':
                current += 2
            else:
                current += 1
            continue

        elif _get_at(current) == 'S':
            # special cases 'island', 'isle', 'carlisle', 'carlysle'
            if _string_at((current - 1), 3, {'ISL', 'YSL'}):
                current += 1
                continue

            # special case 'sugar-'
            elif (current == 0) and _string_at(current, 5, {'SUGAR'}):
                primary, secondary = _metaph_add('X', 'S')
                current += 1
                continue

            elif _string_at(current, 2, {'SH'}):
                # Germanic
                if _string_at((current + 1), 4,
                              {'HEIM', 'HOEK', 'HOLM', 'HOLZ'}):
                    primary, secondary = _metaph_add('S')
                else:
                    primary, secondary = _metaph_add('X')
                current += 2
                continue

            # Italian & Armenian
            elif (_string_at(current, 3, {'SIO', 'SIA'}) or
                  _string_at(current, 4, {'SIAN'})):
                if not _slavo_germanic():
                    primary, secondary = _metaph_add('S', 'X')
                else:
                    primary, secondary = _metaph_add('S')
                current += 3
                continue

            # German & anglicisations, e.g. 'smith' match 'schmidt',
            #                               'snider' match 'schneider'
            # also, -sz- in Slavic language although in Hungarian it is
            #       pronounced 's'
            elif (((current == 0) and
                   _string_at((current + 1), 1, {'M', 'N', 'L', 'W'})) or
                  _string_at((current + 1), 1, {'Z'})):
                primary, secondary = _metaph_add('S', 'X')
                if _string_at((current + 1), 1, {'Z'}):
                    current += 2
                else:
                    current += 1
                continue

            elif _string_at(current, 2, {'SC'}):
                # Schlesinger's rule
                if _get_at(current + 2) == 'H':
                    # dutch origin, e.g. 'school', 'schooner'
                    if _string_at((current + 3), 2,
                                  {'OO', 'ER', 'EN', 'UY', 'ED', 'EM'}):
                        # 'schermerhorn', 'schenker'
                        if _string_at((current + 3), 2, {'ER', 'EN'}):
                            primary, secondary = _metaph_add('X', 'SK')
                        else:
                            primary, secondary = _metaph_add('SK')
                        current += 3
                        continue
                    else:
                        if (((current == 0) and not _is_vowel(3) and
                             (_get_at(3) != 'W'))):
                            primary, secondary = _metaph_add('X', 'S')
                        else:
                            primary, secondary = _metaph_add('X')
                        current += 3
                        continue

                elif _string_at((current + 2), 1, {'I', 'E', 'Y'}):
                    primary, secondary = _metaph_add('S')
                    current += 3
                    continue

                # else
                else:
                    primary, secondary = _metaph_add('SK')
                    current += 3
                    continue

            else:
                # french e.g. 'resnais', 'artois'
                if (current == last) and _string_at((current - 2), 2,
                                                    {'AI', 'OI'}):
                    primary, secondary = _metaph_add('', 'S')
                else:
                    primary, secondary = _metaph_add('S')

                if _string_at((current + 1), 1, {'S', 'Z'}):
                    current += 2
                else:
                    current += 1
                continue

        elif _get_at(current) == 'T':
            if _string_at(current, 4, {'TION'}):
                primary, secondary = _metaph_add('X')
                current += 3
                continue

            elif _string_at(current, 3, {'TIA', 'TCH'}):
                primary, secondary = _metaph_add('X')
                current += 3
                continue

            elif (_string_at(current, 2, {'TH'}) or
                  _string_at(current, 3, {'TTH'})):
                # special case 'thomas', 'thames' or germanic
                if ((_string_at((current + 2), 2, {'OM', 'AM'}) or
                     _string_at(0, 4, {'VAN ', 'VON '}) or
                     _string_at(0, 3, {'SCH'}))):
                    primary, secondary = _metaph_add('T')
                else:
                    primary, secondary = _metaph_add('0', 'T')
                current += 2
                continue

            elif _string_at((current + 1), 1, {'T', 'D'}):
                current += 2
            else:
                current += 1
            primary, secondary = _metaph_add('T')
            continue

        elif _get_at(current) == 'V':
            if _get_at(current + 1) == 'V':
                current += 2
            else:
                current += 1
            primary, secondary = _metaph_add('F')
            continue

        elif _get_at(current) == 'W':
            # can also be in middle of word
            if _string_at(current, 2, {'WR'}):
                primary, secondary = _metaph_add('R')
                current += 2
                continue
            elif ((current == 0) and
                  (_is_vowel(current + 1) or _string_at(current, 2, {'WH'}))):
                # Wasserman should match Vasserman
                if _is_vowel(current + 1):
                    primary, secondary = _metaph_add('A', 'F')
                else:
                    # need Uomo to match Womo
                    primary, secondary = _metaph_add('A')

            # Arnow should match Arnoff
            if ((((current == last) and _is_vowel(current - 1)) or
                 _string_at((current - 1), 5,
                            {'EWSKI', 'EWSKY', 'OWSKI', 'OWSKY'}) or
                 _string_at(0, 3, ['SCH']))):
                primary, secondary = _metaph_add('', 'F')
                current += 1
                continue
            # Polish e.g. 'filipowicz'
            elif _string_at(current, 4, {'WICZ', 'WITZ'}):
                primary, secondary = _metaph_add('TS', 'FX')
                current += 4
                continue
            # else skip it
            else:
                current += 1
                continue

        elif _get_at(current) == 'X':
            # French e.g. breaux
            if (not ((current == last) and
                     (_string_at((current - 3), 3, {'IAU', 'EAU'}) or
                      _string_at((current - 2), 2, {'AU', 'OU'})))):
                primary, secondary = _metaph_add('KS')

            if _string_at((current + 1), 1, {'C', 'X'}):
                current += 2
            else:
                current += 1
            continue

        elif _get_at(current) == 'Z':
            # Chinese Pinyin e.g. 'zhao'
            if _get_at(current + 1) == 'H':
                primary, secondary = _metaph_add('J')
                current += 2
                continue
            elif (_string_at((current + 1), 2, {'ZO', 'ZI', 'ZA'}) or
                  (_slavo_germanic() and ((current > 0) and
                                          _get_at(current - 1) != 'T'))):
                primary, secondary = _metaph_add('S', 'TS')
            else:
                primary, secondary = _metaph_add('S')

            if _get_at(current + 1) == 'Z':
                current += 2
            else:
                current += 1
            continue

        else:
            current += 1

    if max_length > 0:
        primary = primary[:max_length]
        secondary = secondary[:max_length]
    if primary == secondary:
        secondary = ''

    return primary, secondary