trjhtr

Python 3.6.5

Is there any better solution than this one? Particularly the last line. I don't like it.

import re
s = "my_separator first thing my_separator second thing"
data = re.split("(my_separator )", s)[1:]
data = [even+odd for i, odd in enumerate(data) for j, even in enumerate(data) if i%2==1 and j%2==0 and i==j+1]

hjpotters92’s answer is great for fixed separator strings. If the separators vary and one wants to join them with each subsequent match one can use the following two approaches, neither of which requires closures:

1 Generator function

def split_with_separator1(s, sep):
 tokens = iter(re.split(sep, s))
 next(tokens)
 while True:
 yield next(tokens) + next(tokens)

The expression inside the loop works because the Python language guarantees left-to-right evaluation (unlike many other languages, e. g. C).

2 Interleaved slices and binary map

import operator

def split_with_separator2(s, sep)
 tokens = re.split(sep, s)
 return map(operator.add, tokens[1::2], tokens[2::2])

Of course one can slice with itertools.islice instead if one doesn't want to create two ephemeral token list copies.

You can exploit zip and iterators to allow you to pair things together:

data = [a + b for a, b in zip(*[iter(data)]*2)]

You could use just re, and change the separator with a look ahead assertion.

data = re.split(" (?=my_separator)", s)

You can use str.split, and just add the separator back:

sep = 'my_separator '
data = s.split(sep)[1:]
data = [sep + i for i in data]

data = [sep + i for i in s.split(sep)]

As already commented, use the str.split() version itself:

SEPARATOR = "my_separator "
s = "my_separator first thing my_separator second thing"
data = [SEPARATOR + part for part in s.split(SEPARATOR) if part]

your last line "repaired"

import re
s = "my_separator first thing my_separator second thing"
data = re.split("(my_separator )", s)[1:]
data = [data[i]+data[i+1] for i in range(0, len(data), 2)]