Word Count Regex - Python

word_count.py

import re
import collections


def count_words(sentence):
    word_list = re.findall(r"[\da-zA-Z]+(?:\'[\da-zA-Z]+)?", sentence.lower())
    return collections.Counter(word_list)


# Alternative
#------------------------------------------------------------------------------
def unquoted(word):
    if word.startswith("'") and word.endswith("'"):
        return [word for word in word.split("'") if word != ""][0]

    return word


def count_words_alternative(sentence):
    # regex is kept simpler to improve readability
    words = re.findall("[A-Za-z']+|[0-9]+", sentence.lower())

    return collections.Counter(map(unquoted, words))

Derived from the solution of https://github.com/exercism/python/tree/b89880740cc65fc07c2ba2beeefa18cf4cebcebe/exercises/word-count.