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# coding=utf-8
# Copyright 2022-present, the HuggingFace Inc. team.
#
# 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.
"""Contains a utility to iterate by chunks over an iterator."""
import itertools
from typing import Iterable, TypeVar
T = TypeVar("T")
def chunk_iterable(iterable: Iterable[T], chunk_size: int) -> Iterable[Iterable[T]]:
"""Iterates over an iterator chunk by chunk.
Taken from https://stackoverflow.com/a/8998040.
See also https://github.com/huggingface/huggingface_hub/pull/920#discussion_r938793088.
Args:
iterable (`Iterable`):
The iterable on which we want to iterate.
chunk_size (`int`):
Size of the chunks. Must be a strictly positive integer (e.g. >0).
Example:
```python
>>> from huggingface_hub.utils import chunk_iterable
>>> for items in chunk_iterable(range(17), chunk_size=8):
... print(items)
# [0, 1, 2, 3, 4, 5, 6, 7]
# [8, 9, 10, 11, 12, 13, 14, 15]
# [16] # smaller last chunk
```
Raises:
[`ValueError`](https://docs.python.org/3/library/exceptions.html#ValueError)
If `chunk_size` <= 0.
<Tip warning={true}>
The last chunk can be smaller than `chunk_size`.
</Tip>
"""
if not isinstance(chunk_size, int) or chunk_size <= 0:
raise ValueError("`chunk_size` must be a strictly positive integer (>0).")
iterator = iter(iterable)
while True:
try:
next_item = next(iterator)
except StopIteration:
return
yield itertools.chain((next_item,), itertools.islice(iterator, chunk_size - 1))