Python re.sub 问题
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Python re.sub question
提问by netricate
Greetings all,
问候大家，
I'm not sure if this is possible but I'd like to use matched groups in a regex substitution to call variables.
我不确定这是否可行，但我想在正则表达式替换中使用匹配组来调用变量。
a = 'foo'
b = 'bar'
text = 'find a replacement for me [[:a:]] and [[:b:]]'
desired_output = 'find a replacement for me foo and bar'
re.sub('\[\[:(.+):\]\]',group(1),text) #is not valid
re.sub('\[\[:(.+):\]\]','',text) #replaces the value with 'a' or 'b', not var value
thoughts?
想法？
回答by Christian Oudard
You can specify a callback when using re.sub, which has access to the groups: http://docs.python.org/library/re.html#text-munging
您可以在使用 re.sub 时指定回调，它可以访问组：http: //docs.python.org/library/re.html#text-munging
a = 'foo'
b = 'bar'
text = 'find a replacement for me [[:a:]] and [[:b:]]'
desired_output = 'find a replacement for me foo and bar'
def repl(m):
contents = m.group(1)
if contents == 'a':
return a
if contents == 'b':
return b
print re.sub('\[\[:(.+?):\]\]', repl, text)
Also notice the extra ? in the regular expression. You want non-greedy matching here.
还要注意额外的？在正则表达式中。你想在这里进行非贪婪匹配。
I understand this is just sample code to illustrate a concept, but for the example you gave, simple string formatting is better.
我知道这只是用于说明概念的示例代码，但对于您提供的示例，简单的字符串格式会更好。
回答by Noufal Ibrahim
Sounds like overkill. Why not just do something like
听起来有点矫枉过正。为什么不做类似的事情
text = "find a replacement for me %(a)s and %(b)s"%dict(a='foo', b='bar')
?
?
回答by ghostdog74
>>> d={}
>>> d['a'] = 'foo'
>>> d['b'] = 'bar'
>>> text = 'find a replacement for me [[:a:]] and [[:b:]]'
>>> t=text.split(":]]")
>>> for n,item in enumerate(t):
... if "[[:" in item:
... t[n]=item[: item.rindex("[[:") +3 ] + d[ item.split("[[:")[-1]]
...
>>> print ':]]'.join( t )
'find a replacement for me [[:foo:]] and [[:bar:]]'
