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iteration.py
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iteration.py
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#
# Copyright (c) 2022, Neptune Labs Sp. z o.o.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
#
from itertools import chain, islice
from typing import Iterable, List, TypeVar
T = TypeVar("T")
def get_batches(iterable: Iterable[T], *, batch_size: int) -> Iterable[List[T]]:
assert batch_size > 0
source_iter = iter(iterable)
while True:
# return consequent slices of `batch_size` elements
slices = islice(source_iter, batch_size)
try:
first_from_slice = next(slices)
except StopIteration:
# but if there's nothing to return in last slice, close generator instead of returning empty list
return
yield list(chain([first_from_slice], slices))