1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
|
#!/usr/bin/env python3
from itertools import islice
from typing import Any, Iterator, List
def shard(lst: List[Any], size: int) -> Iterator[Any]:
"""
Yield successive size-sized shards from lst.
>>> for sublist in shard([1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12], 3):
... [_ for _ in sublist]
[1, 2, 3]
[4, 5, 6]
[7, 8, 9]
[10, 11, 12]
"""
for x in range(0, len(lst), size):
yield islice(lst, x, x + size)
def flatten(lst: List[Any]) -> List[Any]:
"""
Flatten out a list:
>>> flatten([ 1, [2, 3, 4, [5], 6], 7, [8, [9]]])
[1, 2, 3, 4, 5, 6, 7, 8, 9]
"""
if len(lst) == 0:
return lst
if isinstance(lst[0], list):
return flatten(lst[0]) + flatten(lst[1:])
return lst[:1] + flatten(lst[1:])
def prepend(item: Any, lst: List[Any]) -> List[Any]:
"""
Prepend an item to a list.
>>> prepend('foo', ['bar', 'baz'])
['foo', 'bar', 'baz']
"""
lst.insert(0, item)
return lst
if __name__ == '__main__':
import doctest
doctest.testmod()
|
