Finding last occurrence of substring in string, replacing that

Question

So I have a long list of strings in the same format, and I want to find the last \".\" character in each one, and replace it with \". - \". I\'ve tried using rfind, but I can\'t

Answer 1

To replace from the right:

def replace_right(source, target, replacement, replacements=None):
    return replacement.join(source.rsplit(target, replacements))

In use:

>>> replace_right("asd.asd.asd.", ".", ". -", 1)
'asd.asd.asd. -'