Why my regex with r'string' matches but not 'string' using Python?

Question

The way regex works in Python is so intensely puzzling that it makes me more furious with each passing second. Here\'s my problem:

I understand that this gives a res

Answer 1

The solution is the one you used yourself in the example above: raw strings.

regex = '|'.join(r'\b' + str(state) + r'\b' for state in states)

(Note that I also removed the extra brackets, turning the list comprehension into a generator expression.)