I'm using nltk.stem.porter.PorterStemmer in python to get stems of words.
When I get the stem of "women" and "women's" I get different results respectively: "women" and "women'". For my purposes I need to have both words having the same stem.
In my line of thought both words refer to the same idea/concept and are pretty much the same word suffering a transformation so they should have the same stem.
Why am I getting two different results? Is this correct?
It's necessary to tokenize your text before lemmatizing.
Without tokenization:
>>> from nltk import word_tokenize
>>> from nltk.stem import WordNetLemmatizer
>>> wnl = WordNetLemmatizer()
>>> [wnl.lemmatize(i) for i in "the woman's going home".split()]
['the', "woman's", 'going', 'home']
>>> [wnl.lemmatize(i) for i in "the women's home is in London".split()]
['the', "women's", 'home', 'is', 'in', 'London']
With tokenization:
>>> [wnl.lemmatize(i) for i in word_tokenize("the woman's going home")]
['the', 'woman', "'s", 'going', 'home']
>>> [wnl.lemmatize(i) for i in word_tokenize("the women's home is in London")]
['the', u'woman', "'s", 'home', 'is', 'in', 'London']