CODEWITHSUNDEEP
nlpnltklemmatization
dada
dada

Reputation: 1493

Is nltk wordnet lemmatizer language independent?

Is it true that nltk's wordnet lemmatizer does not depend on the language of the input text ? Would I use the same sequence of commands:

>>> from nltk.stem import WordNetLemmatizer
>>> wnl = WordNetLemmatizer()
>>> print(wnl.lemmatize('dogs'))
dog
>>> print(wnl.lemmatize('churches'))
church
>>> print(wnl.lemmatize('aardwolves'))
aardwolf
>>> print(wnl.lemmatize('abaci'))
abacus
>>> print(wnl.lemmatize('hardrock'))
hardrock

for both english and french for instance ?

Upvotes: 4

Views: 4689

Answers (1)

alvas
alvas

Reputation: 122112

In Short

No, Wordnet lemmatizer in NLTK is only for English.

In Long

If we look at https://github.com/nltk/nltk/blob/develop/nltk/stem/wordnet.py#L15

class WordNetLemmatizer(object):

    def __init__(self):
        pass

    def lemmatize(self, word, pos=NOUN):
        lemmas = wordnet._morphy(word, pos)
        return min(lemmas, key=len) if lemmas else word

    def __repr__(self):
        return '<WordNetLemmatizer>'

It's based on the _morphy() function at https://github.com/nltk/nltk/blob/develop/nltk/corpus/reader/wordnet.py#L1764 which applies several English specific substitutions

    MORPHOLOGICAL_SUBSTITUTIONS = {
    NOUN: [('s', ''), ('ses', 's'), ('ves', 'f'), ('xes', 'x'),
           ('zes', 'z'), ('ches', 'ch'), ('shes', 'sh'),
           ('men', 'man'), ('ies', 'y')],
    VERB: [('s', ''), ('ies', 'y'), ('es', 'e'), ('es', ''),
           ('ed', 'e'), ('ed', ''), ('ing', 'e'), ('ing', '')],
    ADJ: [('er', ''), ('est', ''), ('er', 'e'), ('est', 'e')],
    ADV: []}

MORPHOLOGICAL_SUBSTITUTIONS[ADJ_SAT] = MORPHOLOGICAL_SUBSTITUTIONS[ADJ]

Upvotes: 5

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