mlr_context_torch: Context for Torch Learner

In mlr3torch: Deep Learning with 'mlr3'

Context for Torch Learner

Description

Context for training a torch learner. This is the - mostly read-only - information callbacks have access to through the argument ctx. For more information on callbacks, see CallbackSet.

Public fields

learner

(Learner)
The torch learner.

task_train

(Task)
The training task.

task_valid

(Task or NULL)
The validation task.

loader_train

(torch::dataloader)
The data loader for training.

loader_valid

(torch::dataloader)
The data loader for validation.

measures_train

(list() of Measures)
Measures used for training.

measures_valid

(list() of Measures)
Measures used for validation.

network

(torch::nn_module)
The torch network.

optimizer

(torch::optimizer)
The optimizer.

loss_fn

(torch::nn_module)
The loss function.

total_epochs

(integer(1))
The total number of epochs the learner is trained for.

last_scores_train

(named list() or NULL)
The scores from the last training batch. Names are the ids of the training measures. If LearnerTorch sets eval_freq different from 1, this is NULL in all epochs that don't evaluate the model.

last_scores_valid

(list())
The scores from the last validation batch. Names are the ids of the validation measures. If LearnerTorch sets eval_freq different from 1, this is NULL in all epochs that don't evaluate the model.

last_loss

(numeric(1))
The loss from the last trainings batch.

y_hat

(torch_tensor)
The model's prediction for the current batch.

epoch

(integer(1))
The current epoch.

step

(integer(1))
The current iteration.

prediction_encoder

(⁠function()⁠)
The learner's prediction encoder.

batch

(named list() of torch_tensors)
The current batch.

terminate

(logical(1))
If this field is set to TRUE at the end of an epoch, training stops.

device

(torch::torch_device)
The device.

Methods

Public methods

• ContextTorch$new()

• ContextTorch$clone()

---

Method new()

Creates a new instance of this R6 class.

Usage

ContextTorch$new(
  learner,
  task_train,
  task_valid = NULL,
  loader_train,
  loader_valid = NULL,
  measures_train = NULL,
  measures_valid = NULL,
  network,
  optimizer,
  loss_fn,
  total_epochs,
  prediction_encoder,
  eval_freq = 1L,
  device
)

Arguments

learner

(Learner)
The torch learner.

task_train

(Task)
The training task.

task_valid

(Task or NULL)
The validation task.

loader_train

(torch::dataloader)
The data loader for training.

loader_valid

(torch::dataloader or NULL)
The data loader for validation.

measures_train

(list() of Measures or NULL)
Measures used for training. Default is NULL.

measures_valid

(list() of Measures or NULL)
Measures used for validation.

network

(torch::nn_module)
The torch network.

optimizer

(torch::optimizer)
The optimizer.

loss_fn

(torch::nn_module)
The loss function.

total_epochs

(integer(1))
The total number of epochs the learner is trained for.

prediction_encoder

(⁠function()⁠)
The learner's prediction encoder. See section Inheriting of LearnerTorch.

eval_freq

(integer(1))
The evaluation frequency.

device

(character(1))
The device.

---

Method clone()

The objects of this class are cloneable with this method.

Usage

ContextTorch$clone(deep = FALSE)

Arguments

deep

Whether to make a deep clone.

See Also

Other Callback: TorchCallback, as_torch_callback(), as_torch_callbacks(), callback_set(), mlr3torch_callbacks, mlr_callback_set, mlr_callback_set.checkpoint, mlr_callback_set.progress, mlr_callback_set.tb, mlr_callback_set.unfreeze, t_clbk(), torch_callback()

mlr3torch documentation built on Aug. 26, 2025, 5:09 p.m.