Regular expression to escape regular expressions

Question

Yesterday, I needed to add a file path to a regular expression creating a pattern like this:

"some_pattern/%s/more_pattern" % some_path

In the beginning the regular expression did not match, because some_path contained several regex specific symbols like ? or . . As a quick fix I replaced them with [?]{1} and . with \\. .

However, I asked myself if there isn't a more reliable or better way to clean a string from regex specific symbols.

• Is such functionality supported in the Python Standard library?
• If not, do you know a regular expression to identify all regex symbols and clean them through a substitute?

Answer 1

Just apply re.escape and you'll be fine.

re.escape(string)

Return string with all non-alphanumerics backslashed; this is useful if you want to match an arbitrary literal string that may have regular expression metacharacters in it.