Python 2.x sublist parameter equivalent in 3.x

Question

I'm working some NLP experiments in Python and wanted to implement this function in Python 3.x though the lambda expansion here is giving me a hard time and I'm not sure how it'd be implemented in 3.x; any suggestions?

    candidates = [' '.join(word for word, pos, chunk in group).lower()
              for key, group in itertools.groupby(all_chunks, lambda (word,pos,chunk): chunk != 'O') if key]

The error I get is on this piece since sublist parameters are not supported in 3.x

lambda (word,pos,chunk)

The original source is the extract_candidate_words function here: http://bdewilde.github.io/blog/2014/09/23/intro-to-automatic-keyphrase-extraction/

Answer 1

The syntax in Python3 would be:

lambda word__pos__chunk: word__pos__chunk[2] != 'O'

A lambda function with a three item tuple (word, pos, chunk) gets converted to word__pos__chunk with positional arguments, word__pos__chunk[2] access the third item for example.

more information: pep-3113