如何在Python2.7中使用带有IGNORECASE的re.sub？-HowcanIusere.subwithIGNORECASEinPython2.7?

2  

You do not specify any capturing group in the pattern and use a backreference to Group 1 in the replacement pattern. That causes an issue.

您不在模式中指定任何捕获组,并在替换模式中对组1使用反向引用。这导致了一个问题。

Either define a capturing group in the pattern and use the appropriate backreference in the replacement pattern, or use the \g<0> backreference to the whole match:

在模式中定义捕获组并在替换模式中使用适当的反向引用,或使用\ g <0>反向引用整个匹配:

re.sub("sparta", r"\g<0>", "Here is Sparta.", flags=re.IGNORECASE)

See the Python demo.

请参阅Python演示。

0  

When you use \x in your second string (replacement string I think it's called) where x is a number, python is going to replace it with the group x.

当您在第二个字符串中使用\ x(替换字符串,我认为它被称为),其中x是一个数字,python将用组x替换它。

You can define a group in your regex by wrapping it with parentheses, like so:

您可以通过用括号括起来在正则表达式中定义一个组,如下所示:

re.sub(r"capture (['me]{2})", r'group 1: \1', 'capture me!') # => group 1: me
re.sub(r"capture (['me]{2})", r'group 1: \1', "capture 'em!") # => group 1: 'em

Nested captures? I've lost the count!

嵌套捕获?我输掉了数!

It's the opening bracket that defines it's number:

它是定义它的数字的开始括号:

(this is the first group (this is the second) (this is the third))

Named group

Named group are pretty useful when you use the match object that returns re.match or re.search for example (refer to the docs for more), but also when you use complex regex, because they bring clarity.

当您使用返回re.match或re.search的匹配对象时,命名组非常有用(请参阅文档了解更多信息),以及使用复杂正则表达式时,因为它们带来了清晰度。

You can name a group with the following syntax:

您可以使用以下语法命名组:

(?Pyour pattern)

So, for example:

所以,例如:

re.sub("(?Phello(?P[test]+)) (?P[a-z])", "first: \g") # => first: hello

What is the group 0

The group 0 is the entire match. But, you can't use \0, because it's going to print out \x00 (the actual value of this escaped code). The solution is to use the named group syntax (because regular group are kind of named group: they're name is just an integer): \g<0>. So, for example:

组0是整场比赛。但是,您不能使用\ 0,因为它将打印出\ x00(此转义代码的实际值)。解决方案是使用命名的组语法(因为常规组是一种命名组:它们的名称只是一个整数):\ g <0>。所以,例如:

re.sub(r'[hello]+', r'\g<0>', 'lehleo') # => lehleo

For your problem

This answer is just suppose to explain capturing, not really answering your question, since @Wiktor Stribiżew's one is perfect.

这个答案只是假设解释捕获,而不是真正回答你的问题,因为@WiktorStribiżew的一个是完美的。