Finding last occurrence of substring in string, replacing that

Solution 1:

This should do it

old_string = "this is going to have a full stop. some written sstuff!"
k = old_string.rfind(".")
new_string = old_string[:k] + ". - " + old_string[k+1:]

Solution 2:

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. -'

Solution 3:

I would use a regex:

import re
new_list = [re.sub(r"\.(?=[^.]*$)", r". - ", s) for s in old_list]

Solution 4:

A one liner would be :

str=str[::-1].replace(".",".-",1)[::-1]

Solution 5:

You can use the function below which replaces the first occurrence of the word from right.

def replace_from_right(text: str, original_text: str, new_text: str) -> str:
    """ Replace first occurrence of original_text by new_text. """
    return text[::-1].replace(original_text[::-1], new_text[::-1], 1)[::-1]