# scvi.train.TrainingPlan#

class scvi.train.TrainingPlan(module, lr=0.001, weight_decay=1e-06, eps=0.01, optimizer='Adam', n_steps_kl_warmup=None, n_epochs_kl_warmup=400, reduce_lr_on_plateau=False, lr_factor=0.6, lr_patience=30, lr_threshold=0.0, lr_scheduler_metric='elbo_validation', lr_min=0, max_kl_weight=1.0, min_kl_weight=0.0, **loss_kwargs)[source]#

Lightning module task to train scvi-tools modules.

The training plan is a PyTorch Lightning Module that is initialized with a scvi-tools module object. It configures the optimizers, defines the training step and validation step, and computes metrics to be recorded during training. The training step and validation step are functions that take data, run it through the model and return the loss, which will then be used to optimize the model parameters in the Trainer. Overall, custom training plans can be used to develop complex inference schemes on top of modules. The following developer tutorial will familiarize you more with training plans and how to use them: Constructing a high-level model.

Parameters:
module : BaseModuleClass

A module instance from class BaseModuleClass.

lr : float (default: 0.001)

Learning rate used for optimization.

weight_decay : float (default: 1e-06)

Weight decay used in optimizatoin.

eps : float (default: 0.01)

eps used for optimization.

optimizer : {‘Adam’, ‘AdamW’}Literal[‘Adam’, ‘AdamW’] (default: 'Adam')

One of “Adam” (Adam), “AdamW” (AdamW).

n_steps_kl_warmup : (default: None)

Number of training steps (minibatches) to scale weight on KL divergences from min_kl_weight to max_kl_weight. Only activated when n_epochs_kl_warmup is set to None.

n_epochs_kl_warmup : (default: 400)

Number of epochs to scale weight on KL divergences from min_kl_weight to max_kl_weight. Overrides n_steps_kl_warmup when both are not None.

reduce_lr_on_plateau : bool (default: False)

Whether to monitor validation loss and reduce learning rate when validation set lr_scheduler_metric plateaus.

lr_factor : float (default: 0.6)

Factor to reduce learning rate.

lr_patience : int (default: 30)

Number of epochs with no improvement after which learning rate will be reduced.

lr_threshold : float (default: 0.0)

Threshold for measuring the new optimum.

lr_scheduler_metric : {‘elbo_validation’, ‘reconstruction_loss_validation’, ‘kl_local_validation’}Literal[‘elbo_validation’, ‘reconstruction_loss_validation’, ‘kl_local_validation’] (default: 'elbo_validation')

Which metric to track for learning rate reduction.

lr_min : float (default: 0)

Minimum learning rate allowed.

max_kl_weight : float (default: 1.0)

Maximum scaling factor on KL divergence during training.

min_kl_weight : float (default: 0.0)

Minimum scaling factor on KL divergence during training.

**loss_kwargs

Keyword args to pass to the loss method of the module. kl_weight should not be passed here and is handled automatically.

## Attributes table#

 kl_weight Scaling factor on KL divergence during training. n_obs_training Number of observations in the training set. n_obs_validation Number of observations in the validation set.

## Methods table#

 compute_and_log_metrics(loss_recorder, ...) Computes and logs metrics. Choose what optimizers and learning-rate schedulers to use in your optimization. forward(*args, **kwargs) Passthrough to model.forward(). Initialize train related metrics. Initialize val related metrics. training_step(batch, batch_idx[, optimizer_idx]) Here you compute and return the training loss and some additional metrics for e.g. validation_step(batch, batch_idx) Operates on a single batch of data from the validation set.

## Attributes#

### CHECKPOINT_HYPER_PARAMS_KEY#

TrainingPlan.CHECKPOINT_HYPER_PARAMS_KEY = 'hyper_parameters'#

### CHECKPOINT_HYPER_PARAMS_NAME#

TrainingPlan.CHECKPOINT_HYPER_PARAMS_NAME = 'hparams_name'#

### CHECKPOINT_HYPER_PARAMS_TYPE#

TrainingPlan.CHECKPOINT_HYPER_PARAMS_TYPE = 'hparams_type'#

### T_destination#

TrainingPlan.T_destination#

alias of TypeVar(‘T_destination’, bound=Dict[str, Any])

alias of TypeVar(‘T_destination’, bound=Dict[str, Any]) .. autoattribute:: TrainingPlan.T_destination automatic_optimization ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

TrainingPlan.automatic_optimization[source]#

If set to False you are responsible for calling .backward(), .step(), .zero_grad().

Return type:

bool

### current_epoch#

TrainingPlan.current_epoch[source]#

The current epoch in the Trainer, or 0 if not attached.

Return type:

int

### device#

TrainingPlan.device[source]#
Return type:

### dtype#

TrainingPlan.dtype[source]#
Return type:

### dump_patches#

TrainingPlan.dump_patches: bool = False#

### example_input_array#

TrainingPlan.example_input_array[source]#

The example input array is a specification of what the module can consume in the forward() method. The return type is interpreted as follows:

• Single tensor: It is assumed the model takes a single argument, i.e., model.forward(model.example_input_array)

• Tuple: The input array should be interpreted as a sequence of positional arguments, i.e., model.forward(*model.example_input_array)

• Dict: The input array represents named keyword arguments, i.e., model.forward(**model.example_input_array)

Return type:

Any

### global_rank#

TrainingPlan.global_rank[source]#

The index of the current process across all nodes and devices.

Return type:

int

### global_step#

TrainingPlan.global_step[source]#

Total training batches seen across all epochs.

If no Trainer is attached, this propery is 0.

Return type:

int

### hparams#

TrainingPlan.hparams[source]#

The collection of hyperparameters saved with save_hyperparameters(). It is mutable by the user. For the frozen set of initial hyperparameters, use hparams_initial.

Return type:
Returns:

Mutable hyperparameters dictionary

### hparams_initial#

TrainingPlan.hparams_initial[source]#

The collection of hyperparameters saved with save_hyperparameters(). These contents are read-only. Manual updates to the saved hyperparameters can instead be performed through hparams.

Returns:

immutable initial hyperparameters

Return type:

AttributeDict

### kl_weight#

TrainingPlan.kl_weight[source]#

Scaling factor on KL divergence during training.

### local_rank#

TrainingPlan.local_rank[source]#

The index of the current process within a single node.

Return type:

int

### logger#

TrainingPlan.logger[source]#

Reference to the logger object in the Trainer.

Return type:

Logger | NoneOptional[Logger]

### loggers#

TrainingPlan.loggers[source]#

Reference to the list of loggers in the Trainer.

Return type:

List[Logger]

### n_obs_training#

TrainingPlan.n_obs_training[source]#

Number of observations in the training set.

This will update the loss kwargs for loss rescaling.

Notes

This can get set after initialization

### n_obs_validation#

TrainingPlan.n_obs_validation[source]#

Number of observations in the validation set.

This will update the loss kwargs for loss rescaling.

Notes

This can get set after initialization

### on_gpu#

TrainingPlan.on_gpu[source]#

Returns True if this model is currently located on a GPU.

Useful to set flags around the LightningModule for different CPU vs GPU behavior.

### trainer#

TrainingPlan.trainer[source]#
Return type:

Trainer

### truncated_bptt_steps#

TrainingPlan.truncated_bptt_steps[source]#

Enables Truncated Backpropagation Through Time in the Trainer when set to a positive integer.

It represents the number of times training_step() gets called before backpropagation. If this is > 0, the training_step() receives an additional argument hiddens and is expected to return a hidden state.

Return type:

int

### use_amp#

TrainingPlan.use_amp[source]#

Deprecated since version v1.6..

This property was deprecated in v1.6 and will be removed in v1.8.

Return type:

bool

### training#

TrainingPlan.training: bool#

## Methods#

### compute_and_log_metrics#

TrainingPlan.compute_and_log_metrics(loss_recorder, metrics, mode)[source]#

Computes and logs metrics.

Parameters:
loss_recorder : LossRecorder

LossRecorder object from scvi-tools module

metric_attr_name

The name of the torch metric object to use

mode : str

Postfix string to add to the metric name of extra metrics

### configure_optimizers#

TrainingPlan.configure_optimizers()[source]#

Choose what optimizers and learning-rate schedulers to use in your optimization. Normally you’d need one. But in the case of GANs or similar you might have multiple.

Returns:

Any of these 6 options.

• Single optimizer.

• List or Tuple of optimizers.

• Two lists - The first list has multiple optimizers, and the second has multiple LR schedulers (or multiple lr_scheduler_config).

• Dictionary, with an "optimizer" key, and (optionally) a "lr_scheduler" key whose value is a single LR scheduler or lr_scheduler_config.

• Tuple of dictionaries as described above, with an optional "frequency" key.

• None - Fit will run without any optimizer.

The lr_scheduler_config is a dictionary which contains the scheduler and its associated configuration. The default configuration is shown below.

lr_scheduler_config = {
# REQUIRED: The scheduler instance
"scheduler": lr_scheduler,
# The unit of the scheduler's step size, could also be 'step'.
# 'epoch' updates the scheduler on epoch end whereas 'step'
# updates it after a optimizer update.
"interval": "epoch",
# How many epochs/steps should pass between calls to
# scheduler.step(). 1 corresponds to updating the learning
# rate after every epoch/step.
"frequency": 1,
# Metric to to monitor for schedulers like ReduceLROnPlateau
"monitor": "val_loss",
# If set to True, will enforce that the value specified 'monitor'
# is available when the scheduler is updated, thus stopping
# training if not found. If set to False, it will only produce a warning
"strict": True,
# If using the LearningRateMonitor callback to monitor the
# learning rate progress, this keyword can be used to specify
# a custom logged name
"name": None,
}


When there are schedulers in which the .step() method is conditioned on a value, such as the torch.optim.lr_scheduler.ReduceLROnPlateau scheduler, Lightning requires that the lr_scheduler_config contains the keyword "monitor" set to the metric name that the scheduler should be conditioned on.

Metrics can be made available to monitor by simply logging it using self.log('metric_to_track', metric_val) in your LightningModule.

Note

The frequency value specified in a dict along with the optimizer key is an int corresponding to the number of sequential batches optimized with the specific optimizer. It should be given to none or to all of the optimizers. There is a difference between passing multiple optimizers in a list, and passing multiple optimizers in dictionaries with a frequency of 1:

• In the former case, all optimizers will operate on the given batch in each optimization step.

• In the latter, only one optimizer will operate on the given batch at every step.

This is different from the frequency value specified in the lr_scheduler_config mentioned above.

def configure_optimizers(self):
optimizer_one = torch.optim.SGD(self.model.parameters(), lr=0.01)
optimizer_two = torch.optim.SGD(self.model.parameters(), lr=0.01)
return [
{"optimizer": optimizer_one, "frequency": 5},
{"optimizer": optimizer_two, "frequency": 10},
]


In this example, the first optimizer will be used for the first 5 steps, the second optimizer for the next 10 steps and that cycle will continue. If an LR scheduler is specified for an optimizer using the lr_scheduler key in the above dict, the scheduler will only be updated when its optimizer is being used.

Examples:

# most cases. no learning rate scheduler
def configure_optimizers(self):

# multiple optimizer case (e.g.: GAN)
def configure_optimizers(self):
return gen_opt, dis_opt

# example with learning rate schedulers
def configure_optimizers(self):
dis_sch = CosineAnnealing(dis_opt, T_max=10)
return [gen_opt, dis_opt], [dis_sch]

# example with step-based learning rate schedulers
# each optimizer has its own scheduler
def configure_optimizers(self):
gen_sch = {
'scheduler': ExponentialLR(gen_opt, 0.99),
'interval': 'step'  # called after each training step
}
dis_sch = CosineAnnealing(dis_opt, T_max=10) # called every epoch
return [gen_opt, dis_opt], [gen_sch, dis_sch]

# example with optimizer frequencies
# see training procedure in Improved Training of Wasserstein GANs, Algorithm 1
# https://arxiv.org/abs/1704.00028
def configure_optimizers(self):
n_critic = 5
return (
{'optimizer': dis_opt, 'frequency': n_critic},
{'optimizer': gen_opt, 'frequency': 1}
)


Note

Some things to know:

• Lightning calls .backward() and .step() on each optimizer as needed.

• If learning rate scheduler is specified in configure_optimizers() with key "interval" (default “epoch”) in the scheduler configuration, Lightning will call the scheduler’s .step() method automatically in case of automatic optimization.

• If you use 16-bit precision (precision=16), Lightning will automatically handle the optimizers.

• If you use multiple optimizers, training_step() will have an additional optimizer_idx parameter.

• If you use torch.optim.LBFGS, Lightning handles the closure function automatically for you.

• If you use multiple optimizers, gradients will be calculated only for the parameters of current optimizer at each training step.

• If you need to control how often those optimizers step or override the default .step() schedule, override the optimizer_step() hook.

### forward#

TrainingPlan.forward(*args, **kwargs)[source]#

Passthrough to model.forward().

### initialize_train_metrics#

TrainingPlan.initialize_train_metrics()[source]#

Initialize train related metrics.

### initialize_val_metrics#

TrainingPlan.initialize_val_metrics()[source]#

Initialize val related metrics.

### training_step#

TrainingPlan.training_step(batch, batch_idx, optimizer_idx=0)[source]#

Here you compute and return the training loss and some additional metrics for e.g. the progress bar or logger.

Parameters:
batch : Tensor | (Tensor, …) | [Tensor, …]

The output of your DataLoader. A tensor, tuple or list.

batch_idx : int

Integer displaying index of this batch

optimizer_idx : int

When using multiple optimizers, this argument will also be present.

hiddens : Any
Returns:

Any of.

• Tensor - The loss tensor

• dict - A dictionary. Can include any keys, but must include the key 'loss'

• None - Training will skip to the next batch. This is only for automatic optimization.

This is not supported for multi-GPU, TPU, IPU, or DeepSpeed.

In this step you’d normally do the forward pass and calculate the loss for a batch. You can also do fancier things like multiple forward passes or something model specific.

Example:

def training_step(self, batch, batch_idx):
x, y, z = batch
out = self.encoder(x)
loss = self.loss(out, x)
return loss


If you define multiple optimizers, this step will be called with an additional optimizer_idx parameter.

# Multiple optimizers (e.g.: GANs)
def training_step(self, batch, batch_idx, optimizer_idx):
if optimizer_idx == 0:
# do training_step with encoder
...
if optimizer_idx == 1:
# do training_step with decoder
...


If you add truncated back propagation through time you will also get an additional argument with the hidden states of the previous step.

# Truncated back-propagation through time
def training_step(self, batch, batch_idx, hiddens):
# hiddens are the hidden states from the previous truncated backprop step
out, hiddens = self.lstm(data, hiddens)
loss = ...
return {"loss": loss, "hiddens": hiddens}


Note

The loss value shown in the progress bar is smoothed (averaged) over the last values, so it differs from the actual loss returned in train/validation step.

### validation_step#

TrainingPlan.validation_step(batch, batch_idx)[source]#

Operates on a single batch of data from the validation set. In this step you’d might generate examples or calculate anything of interest like accuracy.

# the pseudocode for these calls
val_outs = []
for val_batch in val_data:
out = validation_step(val_batch)
val_outs.append(out)
validation_epoch_end(val_outs)

Parameters:
batch

The output of your DataLoader.

batch_idx

The index of this batch.

The index of the dataloader that produced this batch. (only if multiple val dataloaders used)

Returns:

• Any object or value

• None - Validation will skip to the next batch

# pseudocode of order
val_outs = []
for val_batch in val_data:
out = validation_step(val_batch)
if defined("validation_step_end"):
out = validation_step_end(out)
val_outs.append(out)
val_outs = validation_epoch_end(val_outs)

# if you have one val dataloader:
def validation_step(self, batch, batch_idx):
...

# if you have multiple val dataloaders:
...


Examples:

# CASE 1: A single validation dataset
def validation_step(self, batch, batch_idx):
x, y = batch

out = self(x)
loss = self.loss(out, y)

# log 6 example images
# or generated text... or whatever
sample_imgs = x[:6]
grid = torchvision.utils.make_grid(sample_imgs)

# calculate acc
labels_hat = torch.argmax(out, dim=1)
val_acc = torch.sum(y == labels_hat).item() / (len(y) * 1.0)

# log the outputs!
self.log_dict({'val_loss': loss, 'val_acc': val_acc})


If you pass in multiple val dataloaders, validation_step() will have an additional argument. We recommend setting the default value of 0 so that you can quickly switch between single and multiple dataloaders.

# CASE 2: multiple validation dataloaders

When the validation_step() is called, the model has been put in eval mode and PyTorch gradients have been disabled. At the end of validation, the model goes back to training mode and gradients are enabled.