Finding Proper Nouns using NLTK WordNet
nltk, python, wordnet
Solution
I don't think you need WordNet to find proper nouns, I suggest using the Part-Of-Speech tagger `pos_tag`.
To find Proper Nouns, look for the `NNP` tag:
from nltk.tag import pos_tag
sentence = "Michael Jackson likes to eat at McDonalds"
tagged_sent = pos_tag(sentence.split())
# [('Michael', 'NNP'), ('Jackson', 'NNP'), ('likes', 'VBZ'), ('to', 'TO'), ('eat', 'VB'), ('at', 'IN'), ('McDonalds', 'NNP')]
propernouns = [word for word,pos in tagged_sent if pos == 'NNP']
# ['Michael','Jackson', 'McDonalds']
You may not be very satisfied since `Michael` and `Jackson` is split into 2 tokens, then you might need something more complex such as Name Entity tagger.
By right, as documented by the `penntreebank` tagset, for possessive nouns, you can simply look for the `POS` tag, http://www.mozart-oz.org/mogul/doc/lager/brill-tagger/penn.html. But often the tagger doesn't tag `POS` when it's an `NNP`.
To find Possessive Nouns, look for str.endswith("'s") or str.endswith("s'"):
from nltk.tag import pos_tag
sentence = "Michael Jackson took Daniel Jackson's hamburger and Agnes' fries"
tagged_sent = pos_tag(sentence.split())
# [('Michael', 'NNP'), ('Jackson', 'NNP'), ('took', 'VBD'), ('Daniel', 'NNP'), ("Jackson's", 'NNP'), ('hamburger', 'NN'), ('and', 'CC'), ("Agnes'", 'NNP'), ('fries', 'NNS')]
possessives = [word for word in sentence if word.endswith("'s") or word.endswith("s'")]
# ["Jackson's", "Agnes'"]
Alternatively, you can use NLTK `ne_chunk` but it doesn't seem to do much other unless you are concerned about what kind of Proper Noun you get from the sentence:
>>> from nltk.tree import Tree; from nltk.chunk import ne_chunk
>>> [chunk for chunk in ne_chunk(tagged_sent) if isinstance(chunk, Tree)]
[Tree('PERSON', [('Michael', 'NNP')]), Tree('PERSON', [('Jackson', 'NNP')]), Tree('PERSON', [('Daniel', 'NNP')])]
>>> [i[0] for i in list(chain(*[chunk.leaves() for chunk in ne_chunk(tagged_sent) if isinstance(chunk, Tree)]))]
['Michael', 'Jackson', 'Daniel']
Using `ne_chunk` is a little verbose and it doesn't get you the possessives.
Problem
Is there any way to find proper nouns using NLTK WordNet?Ie., Can i tag Possessive nouns using nltk Wordnet ?