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

Naïve approach:

a = "A long string with a . in the middle ending with ."
fchar = '.'
rchar = '. -'
a[::-1].replace(fchar, rchar[::-1], 1)[::-1]

Out[2]: 'A long string with a . in the middle ending with . -'

---

Aditya Sihag's answer with a single rfind:

pos = a.rfind('.')
a[:pos] + '. -' + a[pos+1:]