How to identify the subject of a sentence?

Question

Can Python + NLTK be used to identify the subject of a sentence? From what I have learned till now is that a sentence can be broken into a head and its dependents. For e.g.

Answer 1

rake_nltk (pip install rake_nltk) is a python library that wraps nltk and apparently uses the RAKE algorithm.

from rake_nltk import Rake

rake = Rake()

kw = rake.extract_keywords_from_text("Can Python + NLTK be used to identify the subject of a sentence?")

ranked_phrases = rake.get_ranked_phrases()

print(ranked_phrases)

# outputs the keywords ordered by rank
>>> ['used', 'subject', 'sentence', 'python', 'nltk', 'identify']

By default the stopword list from nltk is used. You can provide your custom stopword list and punctuation chars by passing them in the constructor:

rake = Rake(stopwords='mystopwords.txt', punctuations=''',;:!@#$%^*/\''')

By default string.punctuation is used for punctuation.

The constructor also accepts a language keyword which can be any language supported by nltk.