[英]re.sub not working for a particular regex pattern
I am using following code : 我正在使用以下代码:
re.sub(inputpattern,outputpattern, currentline)
in the above code , i am reading the value of outputpattern from csv , whose value is : 在上面的代码中,我正在从csv读取outputpattern的值,其值为:
\\1-\\2-\\3-\\4
I am reading it like below : 我正在阅读如下:
outputpattern = row['PREFIX_1_WRT_FMT']
I have also tried : 我也尝试过:
outputpattern = "'"+ row['PREFIX_1_WRT_FMT'] +"'"
The problem is that it is not treating it as proper format , but if I hard code it like below it works fine : 问题是它没有将其视为正确的格式,但是如果我像下面这样对它进行硬编码,它就可以正常工作:
re.sub(inputpattern,'\\\\1-\\\\2-\\\\3-\\\\4', currentline)
You only need to escape the backslashes if you have it as a literal string. 如果您将反斜杠作为文字字符串使用,则仅需要转义反斜杠。
"\\1-\\2-\\3-\\4"
If you read it from an input you don't have to do that. 如果您从输入中读取它,则不必这样做。 You need to change the pattern inside the CSV to be like \\1-\\2-\\3-\\4
您需要将CSV中的模式更改为\\ 1- \\ 2- \\ 3- \\ 4
You could also use the raw string if you dislike escaping every char when using literal string, by prefixing you string with the letter r. 如果您不喜欢在使用文字字符串时转义每个字符,也可以使用原始字符串,方法是在字符串前加上字母r。
r"\1-\2-\3-\4"
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