TorchLoss function

Torch Loss

This wraps a torch::nn_loss and annotates it with metadata, most importantly a ParamSet. The loss function is created for the given parameter values by calling the $generate() method.

This class is usually used to configure the loss function of a torch learner, e.g. when construcing a learner or in a ModelDescriptor.

For a list of available losses, see mlr3torch_losses. Items from this dictionary can be retrieved using t_loss().

Parameters

Defined by the constructor argument param_set. If no parameter set is provided during construction, the parameter set is constructed by creating a parameter for each argument of the wrapped loss function, where the parametes are then of type ParamUty.

Examples

# Create a new torch loss
torch_loss = TorchLoss$new(torch_loss = nn_mse_loss, task_types = "regr")
torch_loss
# the parameters are inferred
torch_loss$param_set

# Retrieve a loss from the dictionary:
torch_loss = t_loss("mse", reduction = "mean")
# is the same as
torch_loss
torch_loss$param_set
torch_loss$label
torch_loss$task_types
torch_loss$id

# Create the loss function
loss_fn = torch_loss$generate()
loss_fn
# Is the same as
nn_mse_loss(reduction = "mean")

# open the help page of the wrapped loss function
# torch_loss$help()

# Use in a learner
learner = lrn("regr.mlp", loss = t_loss("mse"))
# The parameters of the loss are added to the learner's parameter set
learner$param_set

See Also

Other Torch Descriptor: TorchCallback, TorchDescriptor, TorchOptimizer, as_torch_callbacks(), as_torch_loss(), as_torch_optimizer(), mlr3torch_losses, mlr3torch_optimizers, t_clbk(), t_loss(), t_opt()

Super class

mlr3torch::TorchDescriptor -> TorchLoss

Public fields

• task_types: (character())

   The task types this loss supports.
  

Methods

Public methods

• list("TorchLoss$new()")

• list("TorchLoss$print()")

• list("TorchLoss$clone()")

Method new()

Creates a new instance of this R6 class.

Usage

TorchLoss$new(
  torch_loss,
  task_types = NULL,
  param_set = NULL,
  id = NULL,
  label = NULL,
  packages = NULL,
  man = NULL
)

Arguments

• torch_loss: (nn_loss)

   The loss module.
  

• task_types: (character())

   The task types supported by this loss.
  

• param_set: (ParamSet or NULL)

   The parameter set. If `NULL` (default) it is inferred from `torch_loss`.
  

• id: (character(1))

   The id for of the new object.
  

• label: (character(1))

   Label for the new instance.
  

• packages: (character())

   The R packages this object depends on.
  

• man: (character(1))

   String in the format `[pkg]::[topic]` pointing to a manual page for this object. The referenced help package can be opened via method `$help()`.
  

Method print()

Prints the object

Usage

TorchLoss$print(...)

Arguments

• ...: any

Method clone()

The objects of this class are cloneable with this method.

Usage

TorchLoss$clone(deep = FALSE)

Arguments

• deep: Whether to make a deep clone.