136 – Strict batching

When using itertools.batched with the purpose of reshaping a one-dimensional iterable into sections of a fixed size, set strict=True if you expect the iterable to contain a whole number of sections.

Without it, the final batch may be incomplete:

from itertools import batched

for batch in batched(range(10), 4):
    print(batch)
# (0, 1, 2, 3)
# (4, 5, 6, 7)
# (8, 9)

If you set strict=True, you get a ValueError if the final batch is smaller than the specified size:

from itertools import batched

for batch in batched(range(10), 4):
    print(batch)
# (0, 1, 2, 3)
# (4, 5, 6, 7)
# ValueError

Note that you only get the ValueError once you get to the end of the batched iterable and not when you create the batched iterable:

batched(range(10), 4)  # No error raised yet.