In Python, how do I split a string and keep the separators?

Question

Here\'s the simplest way to explain this. Here\'s what I\'m using:

re.split(\'\\W\', \'foo/bar spam\\neggs\')
-> [\'foo\', \'bar\', \'spam\', \'eggs\']
         


        

Answer 1

Here is a simple .split solution that works without regex.

This is an answer for Python split() without removing the delimiter, so not exactly what the original post asks but the other question was closed as a duplicate for this one.

def splitkeep(s, delimiter):
    split = s.split(delimiter)
    return [substr + delimiter for substr in split[:-1]] + [split[-1]]

Random tests:

import random

CHARS = [".", "a", "b", "c"]
assert splitkeep("", "X") == [""]  # 0 length test
for delimiter in ('.', '..'):
    for _ in range(100000):
        length = random.randint(1, 50)
        s = "".join(random.choice(CHARS) for _ in range(length))
        assert "".join(splitkeep(s, delimiter)) == s