abydos.stemmer.snowball.porter2()

Complexity

Conditions

127

Size

Total Lines	274
Code Lines	211

Duplication

Lines	0
Ratio	0 %

Importance

Changes

0

# -*- coding: utf-8 -*-
def porter2(word, early_english=False):

Too many return statements (7/6)

    """Return the Porter2 (Snowball English) stem.

    The Porter2 (Snowball English) stemmer is defined in :cite:`Porter:2002`.

    :param str word: the word to calculate the stem of
    :param bool early_english: set to True in order to remove -eth & -est
        (2nd & 3rd person singular verbal agreement suffixes)
    :returns: word stem
    :rtype: str

    >>> porter2('reading')
    'read'
    >>> porter2('suspension')
    'suspens'
    >>> porter2('elusiveness')
    'elus'

    >>> porter2('eateth', early_english=True)
    'eat'
    """
    _vowels = {'a', 'e', 'i', 'o', 'u', 'y'}
    _codanonvowels = {"'", 'b', 'c', 'd', 'f', 'g', 'h', 'j', 'k', 'l', 'm',
                      'n', 'p', 'q', 'r', 's', 't', 'v', 'z'}
    _doubles = {'bb', 'dd', 'ff', 'gg', 'mm', 'nn', 'pp', 'rr', 'tt'}
    _li = {'c', 'd', 'e', 'g', 'h', 'k', 'm', 'n', 'r', 't'}

    # R1 prefixes should be in order from longest to shortest to prevent
    # masking
    _r1_prefixes = ('commun', 'gener', 'arsen')
    _exception1dict = {  # special changes:
        'skis': 'ski', 'skies': 'sky', 'dying': 'die',
        'lying': 'lie', 'tying': 'tie',
        # special -LY cases:
        'idly': 'idl', 'gently': 'gentl', 'ugly': 'ugli',
        'early': 'earli', 'only': 'onli', 'singly': 'singl'}
    _exception1set = {'sky', 'news', 'howe', 'atlas', 'cosmos', 'bias',
                      'andes'}
    _exception2set = {'inning', 'outing', 'canning', 'herring', 'earring',
                      'proceed', 'exceed', 'succeed'}

    # lowercase, normalize, and compose
    word = normalize('NFC', text_type(word.lower()))
    # replace apostrophe-like characters with U+0027, per
    # http://snowball.tartarus.org/texts/apostrophe.html
    word = word.replace('’', '\'')
    word = word.replace('’', '\'')

    # Exceptions 1
    if word in _exception1dict:

Unnecessary "elif" after "return"

        return _exception1dict[word]
    elif word in _exception1set:
        return word

    # Return word if stem is shorter than 3
    if len(word) < 3:
        return word

    # Remove initial ', if present.
    while word and word[0] == '\'':
        word = word[1:]
        # Return word if stem is shorter than 2
        if len(word) < 2:
            return word

    # Re-map vocalic Y to y (Y will be C, y will be V)
    if word[0] == 'y':
        word = 'Y' + word[1:]
    for i in range(1, len(word)):
        if word[i] == 'y' and word[i-1] in _vowels:
            word = word[:i] + 'Y' + word[i+1:]

    r1_start = _sb_r1(word, _vowels, _r1_prefixes)
    r2_start = _sb_r2(word, _vowels, _r1_prefixes)

    # Step 0
    if word[-3:] == '\'s\'':
        word = word[:-3]
    elif word[-2:] == '\'s':
        word = word[:-2]
    elif word[-1:] == '\'':
        word = word[:-1]
    # Return word if stem is shorter than 2
    if len(word) < 3:
        return word

    # Step 1a
    if word[-4:] == 'sses':
        word = word[:-2]
    elif word[-3:] in {'ied', 'ies'}:
        if len(word) > 4:
            word = word[:-2]
        else:
            word = word[:-1]
    elif word[-2:] in {'us', 'ss'}:
        pass
    elif word[-1] == 's':
        if _sb_has_vowel(word[:-2], _vowels):
            word = word[:-1]

    # Exceptions 2
    if word in _exception2set:
        return word

    # Step 1b
    step1b_flag = False
    if word[-5:] == 'eedly':
        if len(word[r1_start:]) >= 5:
            word = word[:-3]
    elif word[-5:] == 'ingly':
        if _sb_has_vowel(word[:-5], _vowels):
            word = word[:-5]
            step1b_flag = True
    elif word[-4:] == 'edly':
        if _sb_has_vowel(word[:-4], _vowels):
            word = word[:-4]
            step1b_flag = True
    elif word[-3:] == 'eed':
        if len(word[r1_start:]) >= 3:
            word = word[:-1]
    elif word[-3:] == 'ing':
        if _sb_has_vowel(word[:-3], _vowels):
            word = word[:-3]
            step1b_flag = True
    elif word[-2:] == 'ed':
        if _sb_has_vowel(word[:-2], _vowels):
            word = word[:-2]
            step1b_flag = True
    elif early_english:
        if word[-3:] == 'est':
            if _sb_has_vowel(word[:-3], _vowels):
                word = word[:-3]
                step1b_flag = True
        elif word[-3:] == 'eth':
            if _sb_has_vowel(word[:-3], _vowels):
                word = word[:-3]
                step1b_flag = True

    if step1b_flag:
        if word[-2:] in {'at', 'bl', 'iz'}:
            word += 'e'
        elif word[-2:] in _doubles:
            word = word[:-1]
        elif _sb_short_word(word, _vowels, _codanonvowels, _r1_prefixes):
            word += 'e'

    # Step 1c
    if ((len(word) > 2 and word[-1] in {'Y', 'y'} and
         word[-2] not in _vowels)):
        word = word[:-1] + 'i'

    # Step 2
    if word[-2] == 'a':
        if word[-7:] == 'ational':
            if len(word[r1_start:]) >= 7:
                word = word[:-5] + 'e'
        elif word[-6:] == 'tional':
            if len(word[r1_start:]) >= 6:
                word = word[:-2]
    elif word[-2] == 'c':
        if word[-4:] in {'enci', 'anci'}:
            if len(word[r1_start:]) >= 4:
                word = word[:-1] + 'e'
    elif word[-2] == 'e':
        if word[-4:] == 'izer':
            if len(word[r1_start:]) >= 4:
                word = word[:-1]
    elif word[-2] == 'g':
        if word[-3:] == 'ogi':
            if ((r1_start >= 1 and len(word[r1_start:]) >= 3 and
                 word[-4] == 'l')):
                word = word[:-1]
    elif word[-2] == 'l':
        if word[-6:] == 'lessli':
            if len(word[r1_start:]) >= 6:
                word = word[:-2]
        elif word[-5:] in {'entli', 'fulli', 'ousli'}:
            if len(word[r1_start:]) >= 5:
                word = word[:-2]
        elif word[-4:] == 'abli':
            if len(word[r1_start:]) >= 4:
                word = word[:-1] + 'e'
        elif word[-4:] == 'alli':
            if len(word[r1_start:]) >= 4:
                word = word[:-2]
        elif word[-3:] == 'bli':
            if len(word[r1_start:]) >= 3:
                word = word[:-1] + 'e'
        elif word[-2:] == 'li':
            if ((r1_start >= 1 and len(word[r1_start:]) >= 2 and
                 word[-3] in _li)):
                word = word[:-2]
    elif word[-2] == 'o':
        if word[-7:] == 'ization':
            if len(word[r1_start:]) >= 7:
                word = word[:-5] + 'e'
        elif word[-5:] == 'ation':
            if len(word[r1_start:]) >= 5:
                word = word[:-3] + 'e'
        elif word[-4:] == 'ator':
            if len(word[r1_start:]) >= 4:
                word = word[:-2] + 'e'
    elif word[-2] == 's':
        if word[-7:] in {'fulness', 'ousness', 'iveness'}:
            if len(word[r1_start:]) >= 7:
                word = word[:-4]
        elif word[-5:] == 'alism':
            if len(word[r1_start:]) >= 5:
                word = word[:-3]
    elif word[-2] == 't':
        if word[-6:] == 'biliti':
            if len(word[r1_start:]) >= 6:
                word = word[:-5] + 'le'
        elif word[-5:] == 'aliti':
            if len(word[r1_start:]) >= 5:
                word = word[:-3]
        elif word[-5:] == 'iviti':
            if len(word[r1_start:]) >= 5:
                word = word[:-3] + 'e'

    # Step 3
    if word[-7:] == 'ational':
        if len(word[r1_start:]) >= 7:
            word = word[:-5] + 'e'
    elif word[-6:] == 'tional':
        if len(word[r1_start:]) >= 6:
            word = word[:-2]
    elif word[-5:] in {'alize', 'icate', 'iciti'}:
        if len(word[r1_start:]) >= 5:
            word = word[:-3]
    elif word[-5:] == 'ative':
        if len(word[r2_start:]) >= 5:
            word = word[:-5]
    elif word[-4:] == 'ical':
        if len(word[r1_start:]) >= 4:
            word = word[:-2]
    elif word[-4:] == 'ness':
        if len(word[r1_start:]) >= 4:
            word = word[:-4]
    elif word[-3:] == 'ful':
        if len(word[r1_start:]) >= 3:
            word = word[:-3]

    # Step 4
    for suffix in ('ement', 'ance', 'ence', 'able', 'ible', 'ment', 'ant',
                   'ent', 'ism', 'ate', 'iti', 'ous', 'ive', 'ize', 'al', 'er',
                   'ic'):
        if word[-len(suffix):] == suffix:
            if len(word[r2_start:]) >= len(suffix):
                word = word[:-len(suffix)]
            break
    else:
        if word[-3:] == 'ion':
            if ((len(word[r2_start:]) >= 3 and len(word) >= 4 and
                 word[-4] in tuple('st'))):
                word = word[:-3]

    # Step 5
    if word[-1] == 'e':
        if (len(word[r2_start:]) >= 1 or
                (len(word[r1_start:]) >= 1 and
                 not _sb_ends_in_short_syllable(word[:-1], _vowels,
                                                _codanonvowels))):
            word = word[:-1]
    elif word[-1] == 'l':
        if len(word[r2_start:]) >= 1 and word[-2] == 'l':
            word = word[:-1]

    # Change 'Y' back to 'y' if it survived stemming
    for i in range(0, len(word)):

Consider using enumerate instead of iterating with range and len

        if word[i] == 'Y':
            word = word[:i] + 'y' + word[i+1:]

    return word