## 12.2.10 Normalization: Stemming and Lemmatization¶

- Stemming removes a prefix or suffix from a word leaving only a stem, which may or may not be a real word
- Lemmatization is similar, but factors in the word’s part of speech and meaning and results in a real word
- Both normalize words for analysis
  - Before calculating statistics on words in a body of text, you might convert all words to lowercase so that capitalized and lowercase words are not treated differently.
- You might want to use a word’s root to represent the word’s many forms.
  - E.g., treat "program" and "programs" as "program"

In [1]:

    from textblob import Word

In [2]:

    word = Word('varieties')

In [3]:

    word.stem()

Out[3]:

    'varieti'

In [4]:

    word.lemmatize()

Out[4]:

    'variety'

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