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Source code for pytorch_lightning.callbacks.gradient_accumulation_scheduler

# Copyright The PyTorch Lightning 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.
r"""
Gradient Accumulator
====================

Change gradient accumulation factor according to scheduling.
Trainer also calls ``optimizer.step()`` for the last indivisible step number.

"""

from typing import Dict

from pytorch_lightning.callbacks.base import Callback


[docs]class GradientAccumulationScheduler(Callback): r""" Change gradient accumulation factor according to scheduling. Args: scheduling: scheduling in format {epoch: accumulation_factor} Raises: TypeError: If ``scheduling`` is an empty ``dict``, or not all keys and values of ``scheduling`` are integers. IndexError: If ``minimal_epoch`` is less than 0. Example:: >>> from pytorch_lightning import Trainer >>> from pytorch_lightning.callbacks import GradientAccumulationScheduler # at epoch 5 start accumulating every 2 batches >>> accumulator = GradientAccumulationScheduler(scheduling={5: 2}) >>> trainer = Trainer(callbacks=[accumulator]) # alternatively, pass the scheduling dict directly to the Trainer >>> trainer = Trainer(accumulate_grad_batches={5: 2}) """ def __init__(self, scheduling: Dict[int, int]): super().__init__() if not scheduling: # empty dict error raise TypeError("Empty dict cannot be interpreted correct") for key in scheduling: if not isinstance(key, int) or not isinstance(scheduling[key], int): raise TypeError("All epoches and accumulation factor must be integers") minimal_epoch = min(scheduling.keys()) if minimal_epoch < 0: raise IndexError(f"Epochs indexing from 1, epoch {minimal_epoch} cannot be interpreted correct") if minimal_epoch != 0: # if user didnt define first epoch accumulation factor scheduling.update({0: 1}) self.scheduling = scheduling self.epochs = sorted(scheduling.keys()) def going_to_accumulate_grad_batches(self): return any(v > 1 for v in self.scheduling.values()) def get_accumulate_grad_batches(self, epoch: int) -> int: accumulate_grad_batches = 1 for iter_epoch in reversed(self.epochs): if epoch >= iter_epoch: accumulate_grad_batches = self.scheduling.get(iter_epoch) break return accumulate_grad_batches
[docs] def on_train_epoch_start(self, trainer, *_): trainer.accumulate_grad_batches = self.get_accumulate_grad_batches(trainer.current_epoch)

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