lightning/docs/source/common/fast_training.rst

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.. testsetup:: *
from pytorch_lightning.trainer.trainer import Trainer
.. _fast_training:
Fast Training
=============
There are multiple options to speed up different parts of the training by choosing to train
on a subset of data. This could be done for speed or debugging purposes.
----------------
Check validation every n epochs
-------------------------------
If you have a small dataset you might want to check validation every n epochs
.. testcode::
# DEFAULT
trainer = Trainer(check_val_every_n_epoch=1)
----------------
Force training for min or max epochs
------------------------------------
It can be useful to force training for a minimum number of epochs or limit to a max number.
.. seealso::
:class:`~pytorch_lightning.trainer.trainer.Trainer`
.. testcode::
# DEFAULT
trainer = Trainer(min_epochs=1, max_epochs=1000)
----------------
Set validation check frequency within 1 training epoch
------------------------------------------------------
For large datasets it's often desirable to check validation multiple times within a training loop.
Pass in a float to check that often within 1 training epoch. Pass in an int `k` to check every `k` training batches.
Must use an `int` if using an `IterableDataset`.
.. testcode::
# DEFAULT
trainer = Trainer(val_check_interval=0.95)
# check every .25 of an epoch
trainer = Trainer(val_check_interval=0.25)
# check every 100 train batches (ie: for `IterableDatasets` or fixed frequency)
trainer = Trainer(val_check_interval=100)
----------------
Use data subset for training, validation, and test
--------------------------------------------------
If you don't want to check 100% of the training/validation/test set (for debugging or if it's huge), set these flags.
.. testcode::
# DEFAULT
trainer = Trainer(
limit_train_batches=1.0,
limit_val_batches=1.0,
limit_test_batches=1.0
)
# check 10%, 20%, 30% only, respectively for training, validation and test set
trainer = Trainer(
limit_train_batches=0.1,
limit_val_batches=0.2,
limit_test_batches=0.3
)
If you also pass ``shuffle=True`` to the dataloader, a different random subset of your dataset will be used for each epoch; otherwise the same subset will be used for all epochs.
.. note:: ``limit_train_batches``, ``limit_val_batches`` and ``limit_test_batches`` will be overwritten by ``overfit_batches`` if ``overfit_batches`` > 0. ``limit_val_batches`` will be ignored if ``fast_dev_run=True``.
.. note:: If you set ``limit_val_batches=0``, validation will be disabled.