Is there a way to correctly remove the tense or plural from a word?

Question

Is it possible to to change words like running, helping, cooks, finds and happily into run, help, cook, find and happy using nltk?

Answer 1

There are some stemming algorithms implemented in nltk. It looks like Lancaster stemming algorithm will work for you.

>>> from nltk.stem.lancaster import LancasterStemmer
>>> st = LancasterStemmer()
>>> st.stem('happily')
'happy'
>>> st.stem('cooks')
'cook'
>>> st.stem('helping')
'help'
>>> st.stem('running')
'run'
>>> st.stem('finds')
'find'

Answer 2

>>> from nltk.stem import WordNetLemmatizer
>>> wnl = WordNetLemmatizer()
>>> ls = ['running', 'helping', 'cooks', 'finds']
>>> [wnl.lemmatize(i) for i in ls]
['running', 'helping', u'cook', u'find']
>>> ls = [('running', 'v'), ('helping', 'v'), ('cooks', 'v'), ('finds','v')]
>>> [wnl.lemmatize(word, pos) for word, pos in ls]
[u'run', u'help', u'cook', u'find']
>>> ls = [('running', 'n'), ('helping', 'n'), ('cooks', 'n'), ('finds','n')]
>>> [wnl.lemmatize(word, pos) for word, pos in ls]
['running', 'helping', u'cook', u'find']

See Porter Stemming of fried