TorchOptimizer function

Torch Optimizer

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

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

For a list of available optimizers, see mlr3torch_optimizers. Items from this dictionary can be retrieved using t_opt().

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_opt = TorchOptimizer$new(optim_ignite_adam, label = "adam")
torch_opt
# If the param set is not specified, parameters are inferred but are of class ParamUty
torch_opt$param_set

# open the help page of the wrapped optimizer
# torch_opt$help()

# Retrieve an optimizer from the dictionary
torch_opt = t_opt("sgd", lr = 0.1)
torch_opt
torch_opt$param_set
torch_opt$label
torch_opt$id

# Create the optimizer for a network
net = nn_linear(10, 1)
opt = torch_opt$generate(net$parameters)

# is the same as
optim_sgd(net$parameters, lr = 0.1)

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

See Also

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

Super class

mlr3torch::TorchDescriptor -> TorchOptimizer

Methods

Public methods

• list("TorchOptimizer$new()")

• list("TorchOptimizer$generate()")

• list("TorchOptimizer$clone()")

Method new()

Creates a new instance of this R6 class.

Usage

TorchOptimizer$new(
  torch_optimizer,
  param_set = NULL,
  id = NULL,
  label = NULL,
  packages = NULL,
  man = NULL
)

Arguments

• torch_optimizer: (torch_optimizer_generator)

   The torch optimizer.
  

• param_set: (ParamSet or NULL)

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

• 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 generate()

Instantiates the optimizer.

Usage

TorchOptimizer$generate(params)

Arguments

• params: (named list() of torch_tensors)

   The parameters of the network.
  

Returns

torch_optimizer

Method clone()

The objects of this class are cloneable with this method.

Usage

TorchOptimizer$clone(deep = FALSE)

Arguments

• deep: Whether to make a deep clone.