利用python，简单的词语纠错

利用python，编写一个简单的词语纠正修改器。

原文：http://norvig.com/spell-correct.html

#!/usr/bin/env python
# coding=utf-8

import re,collections
import string

'''
How to Write a Spelling Corrector
http://norvig.com/spell-correct.html
'''

def words(text):
    return re.findall('[a-z]+',text.lower())

def train(features):
    model = collections.defaultdict(lambda:1)
    for f in features:
        model[f] += 1
    return model

NWORDS = train(words(open('big.txt').read()))

alphabet = string.letters

def edits1(word):
    splits = [(word[:i],word[i:]) for i in range(len(word)+1)]
    deletes = [a+b[1:] for a,b in splits if b]
    transposes = [a+b[1]+b[0]+b[2:] for a,b in splits if len(b)>1]
    replaces = [a+c+b[1:] for a,b in splits for c in alphabet if b]
    inserts = [a+c+b for a,b in splits for c in alphabet]
    return set(deletes+transposes+replaces+inserts)

def known_edits2(word):
    return set(e2 for e1 in edits1(word) for e2 in edits1(e1) if e2 in NWORDS)

def known(words):
    return set(w for w in words if w in NWORDS)

def correct(word):
    candidates = known([word]) or known(edits1(word)) or known_edits2(word) or [word]
    return max(candidates,key=NWORDS.get)

ok了，就是这么精简～

>>> correct('speling')
'spelling'
>>> correct('korrecter')
'corrector'