ngrams.py 文件源码

def neighboring_msgs(msg): 
    "Generate nearby keys, hopefully better ones." 
    def swap(a,b): return msg.translate(string.maketrans(a+b, b+a)) 
    for bigram in heapq.nsmallest(20, set(ngrams(msg, 2)), P2l): 
        b1,b2 = bigram 
        for c in alphabet: 
            if b1==b2: 
                if P2l(c+c) > P2l(bigram): yield swap(c,b1) 
            else: 
                if P2l(c+b2) > P2l(bigram): yield swap(c,b1) 
                if P2l(b1+c) > P2l(bigram): yield swap(c,b2) 
    while True: 
        yield swap(random.choice(alphabet), random.choice(alphabet)) 

################ Spelling Correction (p. 236-)