Replace nth occurrence of substring in string

Question

I want to replace the n\'th occurrence of a substring in a string.

There\'s got to be something equivalent to what I WANT to do which is

mystring.repl

Answer 1

The last answer is nearly perfect - only one correction:

    def replacenth(string, sub, wanted, n):
        where = [m.start() for m in re.finditer(sub, string)][n - 1]
        before = string[:where]
        after = string[where:]
        after = after.replace(sub, wanted)
        newString = before + after
        return newString

The after-string has to be stored in the this variable again after replacement. Thank you for the great solution!