119 lines
3.4 KiB
ReStructuredText
119 lines
3.4 KiB
ReStructuredText
.. testsetup:: *
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from pytorch_lightning.core.lightning import LightningModule
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from pytorch_lightning.core.datamodule import LightningDataModule
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from pytorch_lightning.trainer.trainer import Trainer
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.. _converting:
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**************************************
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How to organize PyTorch into Lightning
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**************************************
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To enable your code to work with Lightning, here's how to organize PyTorch into Lightning
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--------
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1. Move your computational code
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===============================
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Move the model architecture and forward pass to your :ref:`lightning_module`.
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.. testcode::
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class LitModel(LightningModule):
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def __init__(self):
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super().__init__()
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self.layer_1 = torch.nn.Linear(28 * 28, 128)
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self.layer_2 = torch.nn.Linear(128, 10)
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def forward(self, x):
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x = x.view(x.size(0), -1)
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x = self.layer_1(x)
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x = F.relu(x)
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x = self.layer_2(x)
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return x
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--------
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2. Move the optimizer(s) and schedulers
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=======================================
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Move your optimizers to the :func:`~pytorch_lightning.core.LightningModule.configure_optimizers` hook.
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.. testcode::
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class LitModel(LightningModule):
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def configure_optimizers(self):
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optimizer = torch.optim.Adam(self.parameters(), lr=1e-3)
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return optimizer
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--------
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3. Find the train loop "meat"
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=============================
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Lightning automates most of the training for you, the epoch and batch iterations, all you need to keep is the training step logic.
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This should go into the :func:`~pytorch_lightning.core.LightningModule.training_step` hook (make sure to use the hook parameters, ``batch`` and ``batch_idx`` in this case):
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.. testcode::
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class LitModel(LightningModule):
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def training_step(self, batch, batch_idx):
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x, y = batch
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y_hat = self(x)
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loss = F.cross_entropy(y_hat, y)
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return loss
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--------
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4. Find the val loop "meat"
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===========================
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To add an (optional) validation loop add logic to the
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:func:`~pytorch_lightning.core.LightningModule.validation_step` hook (make sure to use the hook parameters, ``batch`` and ``batch_idx`` in this case).
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.. testcode::
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class LitModel(LightningModule):
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def validation_step(self, batch, batch_idx):
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x, y = batch
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y_hat = self(x)
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val_loss = F.cross_entropy(y_hat, y)
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return val_loss
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.. note:: ``model.eval()`` and ``torch.no_grad()`` are called automatically for validation
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--------
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5. Find the test loop "meat"
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============================
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To add an (optional) test loop add logic to the
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:func:`~pytorch_lightning.core.LightningModule.test_step` hook (make sure to use the hook parameters, ``batch`` and ``batch_idx`` in this case).
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.. testcode::
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class LitModel(LightningModule):
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def test_step(self, batch, batch_idx):
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x, y = batch
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y_hat = self(x)
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loss = F.cross_entropy(y_hat, y)
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return loss
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.. note:: ``model.eval()`` and ``torch.no_grad()`` are called automatically for testing.
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The test loop will not be used until you call.
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.. code-block::
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trainer.test()
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.. tip:: .test() loads the best checkpoint automatically
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--------
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6. Remove any .cuda() or to.device() calls
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==========================================
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Your :ref:`lightning_module` can automatically run on any hardware!
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