Regular expression to match a dot

A . in regex is a metacharacter, it is used to match any character. To match a literal dot in a raw Python string (r"" or r''), you need to escape it, so r"\."

In your regex you need to escape the dot "\." or use it inside a character class "[.]", as it is a meta-character in regex, which matches any character.

Also, you need \w+ instead of \w to match one or more word characters.

Now, if you want the test.this content, then split is not what you need. split will split your string around the test.this. For example:

>>> re.split(r"\b\w+\.\w+@", s)
['blah blah blah ', 'gmail.com blah blah']

You can use re.findall:

>>> re.findall(r'\w+[.]\w+(?=@)', s)   # look ahead
['test.this']
>>> re.findall(r'(\w+[.]\w+)@', s)     # capture group
['test.this']

"In the default mode, Dot (.) matches any character except a newline. If the DOTALL flag has been specified, this matches any character including a newline." (python Doc)

So, if you want to evaluate dot literaly, I think you should put it in square brackets:

>>> p = re.compile(r'\b(\w+[.]\w+)')
>>> resp = p.search("blah blah blah [email protected] blah blah")
>>> resp.group()
'test.this'

to escape non-alphanumeric characters of string variables, including dots, you could use re.escape:

import re

expression = 'whatever.v1.dfc'
escaped_expression = re.escape(expression)
print(escaped_expression)

output:

whatever\.v1\.dfc

you can use the escaped expression to find/match the string literally.