expression = re.sub('[^\\(\\)]', '', expression)
时间: 2023-07-21 19:09:29 浏览: 142
这段代码使用了 `re.sub()` 函数,它是 Python 中的一个正则表达式函数,用于替换字符串中的匹配项。
具体来说,这段代码使用了正则表达式 `[^\\(\\)]`,表示匹配除了括号之外的字符。然后使用空字符串 `''` 将匹配到的字符替换掉,相当于将字符串中的除了括号之外的字符都删除掉。
以下是一个示例:
```python
import re
expression = "Hello (World)!"
expression = re.sub('[^\\(\\)]', '', expression)
print(expression) # 输出结果为 "()",只保留了原字符串中的括号部分
```
在这个例子中,我们将 `expression` 设置为 "Hello (World)!"。然后使用 `re.sub()` 函数,将除了括号之外的字符替换为空字符串。最后,输出结果为 "()",只保留了原字符串中的括号部分。
这个函数在处理字符串时非常有用,可以根据自己的需求来使用不同的正则表达式进行替换。
相关问题
bd = re.sub('<br(\s+)?/>(\s+)?'," ",bd)
As an AI language model, I cannot tell the exact purpose of this code without proper context. However, I can explain what this line of code does:
This line of code uses the Python `re` module to substitute any occurrence of the `<br/>` or `<br />` tag in the `bd` string with a space character.
Explanation of the code:
- `re.sub()` is a method from the `re` module that substitutes a pattern with a replacement in a string.
- The first argument `'<br(\s )?/>(\s )?'` is a regular expression pattern that matches `<br/>` or `<br />` with optional whitespaces before and after `/`.
- The second argument `" "` is the replacement string that replaces the matched pattern with a space character.
- `bd` is the input string that is being modified by this substitution.
In summary, this line of code replaces all `<br>` tags with a single space character in the `bd` string.
python re.sub
re.sub() is a method in Python's built-in re module that is used to replace one or more occurrences of a pattern in a given string with a replacement string.
Syntax:
re.sub(pattern, repl, string, count=0, flags=0)
Parameters:
- pattern: A regular expression pattern that is to be searched in the string.
- repl: A string that is to be replaced for each occurrence of the pattern.
- string: The input string in which the pattern is to be searched.
- count (optional): Maximum number of occurrences to be replaced.
- flags (optional): One or more optional flags that modify the behavior of the search.
Return Value:
Returns a new string with all the occurrences of the pattern in the input string replaced with the replacement string.
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