lightning/docs/source/experiment_reporting.rst

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Experiment Reporting
=====================
Lightning supports many different experiment loggers. These loggers allow you to monitor losses, images, text, etc...
as training progresses. They usually provide a GUI to visualize and can sometimes even snapshot hyperparameters
used in each experiment.
Control logging frequency
^^^^^^^^^^^^^^^^^^^^^^^^^
It may slow training down to log every single batch. Trainer has an option to log every k batches instead.
.. code-block:: python
# k = 10
Trainer(row_log_interval=10)
Control log writing frequency
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Writing to a logger can be expensive. In Lightning you can set the interval at which you
want to log using this trainer flag.
.. seealso::
:class:`~pytorch_lightning.trainer.trainer.Trainer`
.. code-block:: python
k = 100
Trainer(log_save_interval=k)
Log metrics
^^^^^^^^^^^
To plot metrics into whatever logger you passed in (tensorboard, comet, neptune, TRAINS, etc...)
1. training_epoch_end, validation_epoch_end, test_epoch_end will all log anything in the "log" key of the return dict.
.. code-block:: python
def training_epoch_end(self, outputs):
loss = some_loss()
...
logs = {'train_loss': loss}
results = {'log': logs}
return results
def validation_epoch_end(self, outputs):
loss = some_loss()
...
logs = {'val_loss': loss}
results = {'log': logs}
return results
def test_epoch_end(self, outputs):
loss = some_loss()
...
logs = {'test_loss': loss}
results = {'log': logs}
return results
2. In addition, you can also use any arbitrary functionality from a particular logger from within your LightningModule.
For instance, here we log images using tensorboard.
.. code-block:: python
def training_step(self, batch, batch_idx):
self.generated_imgs = self.decoder.generate()
sample_imgs = self.generated_imgs[:6]
grid = torchvision.utils.make_grid(sample_imgs)
self.logger.experiment.add_image('generated_images', grid, 0)
...
return results
Modify progress bar
^^^^^^^^^^^^^^^^^^^
Each return dict from the training_end, validation_end, testing_end and training_step also has
a key called "progress_bar".
Here we show the validation loss in the progress bar
.. code-block:: python
def validation_epoch_end(self, outputs):
loss = some_loss()
...
logs = {'val_loss': loss}
results = {'progress_bar': logs}
return results
Snapshot hyperparameters
^^^^^^^^^^^^^^^^^^^^^^^^
When training a model, it's useful to know what hyperparams went into that model.
When Lightning creates a checkpoint, it stores a key "hparams" with the hyperparams.
.. code-block:: python
lightning_checkpoint = torch.load(filepath, map_location=lambda storage, loc: storage)
hyperparams = lightning_checkpoint['hparams']
Some loggers also allow logging the hyperparams used in the experiment. For instance,
when using the TestTubeLogger or the TensorBoardLogger, all hyperparams will show
in the `hparams tab <https://pytorch.org/docs/stable/tensorboard.html#torch.utils.tensorboard.writer.SummaryWriter.add_hparams>`_.
Snapshot code
^^^^^^^^^^^^^
Loggers also allow you to snapshot a copy of the code used in this experiment.
For example, TestTubeLogger does this with a flag:
.. code-block:: python
from pytorch_lightning.loggers import TestTubeLogger
logger = TestTubeLogger(create_git_tag=True)