import sys, re, string

def extract_words(path_to_file):
    with open(path_to_file) as f:
        str_data = f.read()
    pattern = re.compile('[\W_]+')
    word_list = pattern.sub(' ', str_data).lower().split()

    with open('../stop_words.txt') as f:
        stop_words = f.read().split(',')
    stop_words.extend(list(string.ascii_lowercase))

    return [w for w in word_list if not w in stop_words]