给定字符串替换子字符串，将字符串替换为键，替换为值。蟒蛇

Question

我有一个字典，字符串将被替换为keys并将其替换为值。除了通过令牌查看字符串令牌之外，还有更好/更快的替换方法吗？

我一直在这样做：

segmenter = {'foobar':'foo bar', 'withoutspace':'without space', 'barbar': 'bar bar'}

sentence = "this is a foobar in a barbar withoutspace"

for i in sentence.split():
  if i in segmenter:
    sentence.replace(i, segmenter[i])

Answer 1

字符串在python中是不可变的。因此，str.replace返回一个新字符串，而不是修改原始字符串。你可以在这里使用str.join()和list comprehension：

>>> segmenter = {'foobar':'foo bar', 'withoutspace':'without space', 'barbar': 'bar bar'}
>>> sentence = "this is a foobar in a barbar withoutspace"

>>> " ".join( [ segmenter.get(word,word) for word in sentence.split()] )
'this is a foo bar in a bar bar without space'

str.replace的另一个问题是它也会替换像"abarbarb"这样的词

"abar barb"。

Answer 2

re.sub可以调用返回替换的函数

segmenter = {'foobar':'foo bar', 'withoutspace':'without space', 'barbar': 'bar bar'}
sentence = "this is a foobar in a barbar withoutspace"

import re

def fn(match):
    return segmenter[match.group()]

print re.sub('|'.join(re.escape(k) for k in segmenter), fn, sentence)