def test_zip_longest(self):
self.assertEqual([
list(g)
for g in python_utils.zip_longest([0, 1, 2, 3], [4, 5, 6], [7, 8])
], [[0, 4, 7], [1, 5, 8], [2, 6, None], [3, None, None]])
# Zip longest with fillvalue.
self.assertEqual([
''.join(g)
for g in python_utils.zip_longest('ABC', 'DE', 'F', fillvalue='x')
], ['ADF', 'BEx', 'Cxx'])
def grouper(
iterable: Iterable[T],
chunk_len: int,
fillvalue: Optional[T] = None
) -> Iterable[Iterable[T]]:
"""Collect data into fixed-length chunks.
Source: https://docs.python.org/3/library/itertools.html#itertools-recipes.
Example:
grouper('ABCDEFG', 3, 'x') --> ABC DEF Gxx
Args:
iterable: iterable. Any kind of iterable object.
chunk_len: int. The chunk size of each group.
fillvalue: *. The value used to fill out the last chunk in case the
iterable is exhausted.
Returns:
iterable(iterable). A sequence of chunks over the input data.
"""
# To understand how/why this works, please refer to the following
# Stack Overflow answer: https://stackoverflow.com/a/49181132/4859885.
args = [iter(iterable)] * chunk_len
return python_utils.zip_longest(*args, fillvalue=fillvalue) # type: ignore[no-any-return, no-untyped-call]