正则表达式替换“转义的"带有原始字符的字符 [英] Regular expression to replace "escaped" characters with their originals
问题描述
注意:我没有用正则表达式解析很多html或通用html.我知道这很糟糕
TL; DR :
我有类似的字符串
A sentence with an exclamation\! Next is a \* character
原始标记中有转义"字符的位置.我希望用他们的原著"代替它们.并得到:
Where there are "escaped" characters in the original markup. I wish to replace them with their "originals". And get:
A sentence with an exclamation! Next is a * character
我需要从一些Wiki标记中提取少量数据.
I have a small bit data that I need to extract from some wiki markup.
我在这里只处理段落/摘要，所以我不需要强大的解决方案.在python中，我尝试了一个测试:
I'm only dealing with paragraphs/snippets here, so I don't need a big robust solution. In python, I tried a test:
s = "test \\* \\! test * !! **"
r = re.compile("""\\.""") # Slash followed by anything
r.sub("-", s)
应该收益:
test - - test * !! **
但是它什么也没做.我在这里想念东西吗?
But it doesn't do anything. Am I missing something here?
此外，我不确定如何用其原始字符替换任何给定的转义字符，因此我可能只用特定的正则表达式列出和替换:
Furthermore, I'm not sure how to go about replacing any given escaped character with its original, so I would probably just make a list and sub with specific regexes like:
\\\*
和
\\!
执行此操作的方法可能更简洁，因此非常感谢您的帮助.
There's probably a much cleaner way to do this, so any help is greatly appreciated.
推荐答案
您缺少某些内容，即r前缀:
You are missing something, namely the r prefix:
r = re.compile(r"\\.") # Slash followed by anything
python和re都将\附加含义；当您将字符串值传递给re.compile()时，您加倍的反斜杠将变成一个反斜杠，此时re看到\.，意味着字面句号.:
Both python and re attach meaning to \; your doubled backslash becomes just one backslash when you pass the string value to re.compile(), by which time re sees \., meaning a literal full stop.:
>>> print """\\."""
\.
通过使用r''，您告诉python不要解释转义码，因此现在re被赋予了带有\\.的字符串，这意味着在其后加任何字符的文字反斜杠:
By using r'' you tell python not to interpret escape codes, so now re is given a string with \\., meaning a literal backslash followed by any character:
>>> print r"""\\."""
\\.
演示:
>>> import re
>>> s = "test \\* \\! test * !! **"
>>> r = re.compile(r"\\.") # Slash followed by anything
>>> r.sub("-", s)
'test - - test * !! **'
经验法则是:在定义正则表达式时，请使用r''原始字符串文字，从而使您不必对具有Python和正则表达式语法含义的所有内容进行两次转义.
The rule of thumb is: when defining regular expressions, use r'' raw string literals, saving you to have to double-escape everything that has meaning to both Python and regular expression syntax.
接下来，您要替换转义"字符；使用组，re.sub()允许您将组作为替换值:
Next, you want to replace the 'escaped' character; use groups for that, re.sub() lets you reference groups as the replacement value:
r = re.compile(r"\\(.)") # Note the parethesis, that's a capturing group
r.sub(r'\1', s) # \1 means: replace with value of first capturing group
现在的输出是:
>>> r = re.compile(r"\\(.)") # Note the parethesis, that's a capturing group
>>> r.sub(r'\1', s)
'test * ! test * !! **'
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