# Copyright 2020 - 2021 MONAI Consortium
# 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.
import torch
from torch.utils.data import DataLoader as _TorchDataLoader
from torch.utils.data import Dataset
from monai.data.utils import list_data_collate, set_rnd, worker_init_fn
__all__ = ["DataLoader"]
[docs]class DataLoader(_TorchDataLoader):
"""Generates images/labels for train/validation/testing from dataset.
It inherits from PyTorch DataLoader and adds default callbacks for `collate`
and `worker_fn` if user doesn't set them.
More information about PyTorch DataLoader, please check:
https://github.com/pytorch/pytorch/blob/master/torch/utils/data/dataloader.py
Args:
dataset: dataset from which to load the data.
num_workers: how many subprocesses to use for data
loading. ``0`` means that the data will be loaded in the main process.
(default: ``0``)
kwargs: other parameters for PyTorch DataLoader.
"""
def __init__(self, dataset: Dataset, num_workers: int = 0, **kwargs) -> None:
if num_workers == 0:
# when num_workers > 0, random states are determined by worker_init_fn
# this is to make the behavior consistent when num_workers == 0
# torch.int64 doesn't work well on some versions of windows
_seed = torch.empty((), dtype=torch.int32).random_(generator=None).item()
set_rnd(dataset, int(_seed))
if "collate_fn" not in kwargs:
kwargs.update({"collate_fn": list_data_collate})
if "worker_init_fn" not in kwargs:
kwargs.update({"worker_init_fn": worker_init_fn})
super().__init__( # type: ignore[call-overload]
dataset=dataset,
num_workers=num_workers,
**kwargs,
)