Python 正则表达式未找到特定模式

Question

我正在尝试从 html 代码中解析乳胶代码，如下所示：

string = " your answer is wrong! Solution: based on \((\vec{n_E},\vec{g})= 0 \) and \(d(g,E)=0\) beeing ... "

我想用一个函数的输出替换所有的乳胶代码，该函数将乳胶代码作为参数（由于找到正确的模式有问题，函数 extract returns目前为空字符串）。

我试过了：

latex_end = "\)"
latex_start = "\("    
string = re.sub(r'{}.*?{}'.format(latex_start, latex_end), extract, string)

结果：

your answer is wrong! Solution: based on \= 0 \) and \=0\) beeing ...

预计：

your answer is wrong! Solution: based on and beeing ...

知道为什么找不到模式吗？有实现的方法吗？

Answer 1

这是因为反斜杠在 Python 中用作转义字符。这使得处理这些情况非常棘手。以下是完成这项工作的两种快速方法：

import re

extract = lambda a: ""

# Using no raw components
string = " your answer is wrong! Solution: based on \((\vec{n_E},\vec{g})= 0 \) and \(d(g,E)=0\) beeing ... "
latex_bounds = ("\\(", "\\)\)")
print(re.sub('{}.*?{}'.format(*latex_bounds), extract, string))

# Using all raw components (backslashes mean nothing, but not really)
string = r"%s" % string
latex_bounds = (r"\\(", r"\\)")
print(re.sub(r'{}.*?{}'.format(*latex_bounds), extract, string))

Answer 2

您应该使用原始字符串来定义 string，因为 \v 被解释为特殊字符。

import re

string = r" your answer is wrong! Solution: based on \((\vec{n_E},\vec{g})= 0 \) and \(d(g,E)=0\) beeing ... "


string = re.sub(r'\\(.*?\\)', '', string))
print(string)

打印：

 your answer is wrong! Solution: based on  and  beeing ...

如果您需要开始和结束的变量：

latex_end = r"\\)"
latex_start = r"\\("    
string = re.sub(r'{}.*?{}'.format(latex_start, latex_end), '', string)
print(string)

Python 正则表达式未找到特定模式

Python regex doesn't find certain pattern

python

regex

string-parsing