spell_checker.py

# Spelpipl check packages
import re
from collections import Counter


WORDS_path = "/usr/share/dict/american-english"

def words(text):
	"Returns all words of `text` in lowercase"
	return re.findall(r'\w+', text.lower())

# Word Count of all words in the specified file
WORDS = Counter(words(open(WORDS_path).read()))

def P(word, N=sum(WORDS.values())):
	"Probability of `word`."
	return WORDS[word] / N

def correction(word):
	"Most probable spelling correction for `word`"
	return max(candidates(word), key=P)

def candidates(word):
	"Generate possible spelling corrections for `word`"
	return (known([word]) or known(edits1(word)) or known(edits2(word)) or [word])

def known(words):
	"The subset of `words` that appear in the dictionary of WORDS."
	return set(w for w in words if w in WORDS)

def edits1(word):
    '''
    All edits that are one edit away from `word`.
    '''
    letters    = 'abcdefghijklmnopqrstuvwxyz'
    splits     = [(word[:i], word[i:])    for i in range(len(word) + 1)]
    deletes    = [L + R[1:]               for L, R in splits if R]
    transposes = [L + R[1] + R[0] + R[2:] for L, R in splits if len(R)>1]
    replaces   = [L + c + R[1:]           for L, R in splits if R for c in letters]
    inserts    = [L + c + R               for L, R in splits for c in letters]
    return set(deletes + transposes + replaces + inserts)

def edits2(word):
	"All edits that are two edits away from `word`"
	return (e2 for e1 in edits1(word) for e2 in edits1(e1))