How to find collocations in text, python

Question

How do you find collocations in text? A collocation is a sequence of words that occurs together unusually often. python has built-in func bigrams that returns word pairs.

>>> bigrams(['more', 'is', 'said', 'than', 'done'])
[('more', 'is'), ('is', 'said'), ('said', 'than'), ('than', 'done')]
>>>

What's left is to find bigrams that occur more often based on the frequency of individual words. Any ideas how to put it in the code?

Answer 1

Try NLTK. You will mostly be interested in nltk.collocations.BigramCollocationFinder, but here is a quick demonstration to show you how to get started:

>>> import nltk
>>> def tokenize(sentences):
...     for sent in nltk.sent_tokenize(sentences.lower()):
...         for word in nltk.word_tokenize(sent):
...             yield word
... 

>>> nltk.Text(tkn for tkn in tokenize('mary had a little lamb.'))
<Text: mary had a little lamb ....>
>>> text = nltk.Text(tkn for tkn in tokenize('mary had a little lamb.'))

There are none in this small segment, but here goes:

>>> text.collocations(num=20)
Building collocations list