Pipe operator

Description

See magrittr::%>% for details.

Usage

lhs %>% rhs

Create an accelerator

Description

Create an accelerator

Usage

accelerator(
  device_placement = TRUE,
  cpu = FALSE,
  cuda_index = torch::cuda_current_device()
)

Arguments

Creates a dataloader from its input

Description

as_dataloader is used internally by luz to convert input data and valid_data as passed to fit.luz_module_generator() to a torch::dataloader

Usage

as_dataloader(x, ...)

## S3 method for class 'dataset'
as_dataloader(x, ..., batch_size = 32)

## S3 method for class 'list'
as_dataloader(x, ...)

## S3 method for class 'dataloader'
as_dataloader(x, ...)

## S3 method for class 'matrix'
as_dataloader(x, ...)

## S3 method for class 'numeric'
as_dataloader(x, ...)

## S3 method for class 'array'
as_dataloader(x, ...)

## S3 method for class 'torch_tensor'
as_dataloader(x, ...)

Arguments

Details

as_dataloader methods should have sensible defaults for batch_size, parallel workers, etc.

It allows users to quickly experiment with fit.luz_module_generator() by not requiring to create a torch::dataset and a torch::dataloader in simple experiments.

Methods (by class)

• as_dataloader(dataset): Converts a torch::dataset() to a torch::dataloader().

• as_dataloader(list): Converts a list of tensors or arrays with the same size in the first dimension to a torch::dataloader()

• as_dataloader(dataloader): Returns the same dataloader

• as_dataloader(matrix): Converts the matrix to a dataloader

• as_dataloader(numeric): Converts the numeric vector to a dataloader

• as_dataloader(array): Converts the array to a dataloader

• as_dataloader(torch_tensor): Converts the tensor to a dataloader

Overriding

You can implement your own as_dataloader S3 method if you want your data structure to be automatically supported by luz's fit.luz_module_generator(). The method must satisfy the following conditions:

• The method should return a torch::dataloader().

• The only required argument is x. You have good default for all other arguments.

It's better to avoid implementing as_dataloader methods for common S3 classes like data.frames. In this case, its better to assign a different class to the inputs and implement as_dataloader for it.

Context object

Description

Context object storing information about the model training context. See also ctx.

Public fields

Active bindings

Methods

Public methods

• context$new()

• context$log()

• context$log_metric()

• context$get_log()

• context$get_metrics()

• context$get_metric()

• context$get_formatted_metrics()

• context$get_metrics_df()

• context$set_verbose()

• context$clean()

• context$call_callbacks()

• context$state_dict()

• context$unsafe_set_records()

• context$clone()

Method new()

Initializes the context object with minimal necessary information.

Usage

context$new(verbose, accelerator, callbacks, training)

Arguments

Method log()

Allows logging arbitrary information in the ctx.

Usage

context$log(what, set, value, index = NULL, append = TRUE)

Arguments

Method log_metric()

Log a metric gen its name and value. Metric values are indexed by epoch.

Usage

context$log_metric(name, value)

Arguments

Method get_log()

Get a specific value from the log.

Usage

context$get_log(what, set, index = NULL)

Arguments

Method get_metrics()

Get all metric given an epoch and set.

Usage

context$get_metrics(set, epoch = NULL)

Arguments

Method get_metric()

Get the value of a metric given its name, epoch and set.

Usage

context$get_metric(name, set, epoch = NULL)

Arguments

Method get_formatted_metrics()

Get formatted metrics values

Usage

context$get_formatted_metrics(set, epoch = NULL)

Arguments

Method get_metrics_df()

Get a data.frame containing all metrics.

Usage

context$get_metrics_df()

Method set_verbose()

Allows setting the verbose attribute.

Usage

context$set_verbose(verbose = NULL)

Arguments

Method clean()

Removes unnecessary information from the context object.

Usage

context$clean()

Method call_callbacks()

Call the selected callbacks. Where name is the callback types to call, eg 'on_epoch_begin'.

Usage

context$call_callbacks(name)

Arguments

Method state_dict()

Returns a list containing minimal information from the context. Used to create the returned values.

Usage

context$state_dict()

Method unsafe_set_records()

Are you sure you know what you are doing?

Usage

context$unsafe_set_records(records)

Arguments

Method clone()

The objects of this class are cloneable with this method.

Usage

context$clone(deep = FALSE)

Arguments

Context object

Description

Context objects used in luz to share information between model methods, metrics and callbacks.

Details

The ctx object is used in luz to share information between the training loop and callbacks, model methods, and metrics. The table below describes information available in the ctx by default. Other callbacks could potentially modify these attributes or add new ones.

Context attributes

See Also

Context object: context

Evaluates a fitted model on a dataset

Description

Evaluates a fitted model on a dataset

Usage

evaluate(
  object,
  data,
  ...,
  metrics = NULL,
  callbacks = list(),
  accelerator = NULL,
  verbose = NULL,
  dataloader_options = NULL
)

Arguments

Details

Once a model has been trained you might want to evaluate its performance on a different dataset. For that reason, luz provides the ?evaluate function that takes a fitted model and a dataset and computes the metrics attached to the model.

Evaluate returns a luz_module_evaluation object that you can query for metrics using the get_metrics function or simply print to see the results.

For example:

evaluation <- fitted %>% evaluate(data = valid_dl)
metrics <- get_metrics(evaluation)
print(evaluation)

## A `luz_module_evaluation`
## -- Results ---------------------------------------------------------------------
## loss: 1.5146
## mae: 1.0251
## mse: 1.5159
## rmse: 1.2312

See Also

Other training: fit.luz_module_generator(), predict.luz_module_fitted(), setup()

Fit a nn_module

Description

Fit a nn_module

Usage

## S3 method for class 'luz_module_generator'
fit(
  object,
  data,
  epochs = 10,
  callbacks = NULL,
  valid_data = NULL,
  accelerator = NULL,
  verbose = NULL,
  ...,
  dataloader_options = NULL
)

Arguments

Value

A fitted object that can be saved with luz_save() and can be printed with print() and plotted with plot().

See Also

predict.luz_module_fitted() for how to create predictions. setup() to find out how to create modules that can be trained with fit.

Other training: evaluate(), predict.luz_module_fitted(), setup()

Get metrics from the object

Description

Get metrics from the object

Usage

get_metrics(object, ...)

## S3 method for class 'luz_module_fitted'
get_metrics(object, ...)

Arguments

Value

A data.frame containing the metric values.

Methods (by class)

• get_metrics(luz_module_fitted): Extract metrics from a luz fitted model.

Learning Rate Finder

Description

Learning Rate Finder

Usage

lr_finder(
  object,
  data,
  steps = 100,
  start_lr = 1e-07,
  end_lr = 0.1,
  log_spaced_intervals = TRUE,
  ...,
  verbose = NULL
)

Arguments

Value

A dataframe with two columns: learning rate and loss

Examples

if (torch::torch_is_installed()) {
library(torch)
ds <- torch::tensor_dataset(x = torch_randn(100, 10), y = torch_randn(100, 1))
dl <- torch::dataloader(ds, batch_size = 32)
model <- torch::nn_linear
model <- model %>% setup(
  loss = torch::nn_mse_loss(),
  optimizer = torch::optim_adam
) %>%
  set_hparams(in_features = 10, out_features = 1)
records <- lr_finder(model, dl, verbose = FALSE)
plot(records)
}

Create a new callback

Description

Create a new callback

Usage

luz_callback(
  name = NULL,
  ...,
  private = NULL,
  active = NULL,
  parent_env = parent.frame(),
  inherit = NULL
)

Arguments

Details

Let’s implement a callback that prints ‘Iteration n’ (where n is the iteration number) for every batch in the training set and ‘Done’ when an epoch is finished. For that task we use the luz_callback function:

print_callback <- luz_callback(
  name = "print_callback",
  initialize = function(message) {
    self$message <- message
  },
  on_train_batch_end = function() {
    cat("Iteration ", ctx$iter, "\n")
  },
  on_epoch_end = function() {
    cat(self$message, "\n")
  }
)

luz_callback() takes named functions as ... arguments, where the name indicates the moment at which the callback should be called. For instance on_train_batch_end() is called for every batch at the end of the training procedure, and on_epoch_end() is called at the end of every epoch.

The returned value of luz_callback() is a function that initializes an instance of the callback. Callbacks can have initialization parameters, like the name of a file where you want to log the results. In that case, you can pass an initialize method when creating the callback definition, and save these parameters to the self object. In the above example, the callback has a message parameter that is printed at the end of each epoch.

Once a callback is defined it can be passed to the fit function via the callbacks parameter:

fitted <- net %>%
  setup(...) %>%
  fit(..., callbacks = list(
    print_callback(message = "Done!")
  ))

Callbacks can be called in many different positions of the training loop, including combinations of them. Here’s an overview of possible callback breakpoints:

Start Fit
   - on_fit_begin
  Start Epoch Loop
     - on_epoch_begin
    Start Train
       - on_train_begin
      Start Batch Loop
         - on_train_batch_begin
          Start Default Training Step
            - on_train_batch_after_pred
            - on_train_batch_after_loss
            - on_train_batch_before_backward
            - on_train_batch_before_step
            - on_train_batch_after_step
          End Default Training Step:
         - on_train_batch_end
      End Batch Loop
       - on_train_end
    End Train
    Start Valid
       - on_valid_begin
      Start Batch Loop
         - on_valid_batch_begin
          Start Default Validation Step
            - on_valid_batch_after_pred
            - on_valid_batch_after_loss
          End Default Validation Step
         - on_valid_batch_end
      End Batch Loop
       - on_valid_end
    End Valid
      - on_epoch_end
  End Epoch Loop
   - on_fit_end
End Fit

Every step market with ⁠on_*⁠ is a point in the training procedure that is available for callbacks to be called.

The other important part of callbacks is the ctx (context) object. See help("ctx") for details.

By default, callbacks are called in the same order as they were passed to fit (or predict or evaluate), but you can provide a weight attribute that will control the order in which it will be called. For example, if one callback has weight = 10 and another has weight = 1, then the first one is called after the second one. Callbacks that don’t specify a weight attribute are considered weight = 0. A few built-in callbacks in luz already provide a weight value. For example, the ?luz_callback_early_stopping has a weight of Inf, since in general we want to run it as the last thing in the loop.

Value

A luz_callback that can be passed to fit.luz_module_generator().

Prediction callbacks

You can also use callbacks when using predict(). In this case the supported callback methods are detailed above.

Start predict
 - on_predict_begin
 Start prediction loop
  - on_predict_batch_begin
  - on_predict_batch_end
 End prediction loop
 - on_predict_end
End predict

Evaluate callbacks

Callbacks can also be used with evaluate(), in this case, the callbacks that are used are equivalent to those of the validation loop when using fit():

Start Valid
 - on_valid_begin
 Start Batch Loop
  - on_valid_batch_begin
  Start Default Validation Step
   - on_valid_batch_after_pred
   - on_valid_batch_after_loss
  End Default Validation Step
  - on_valid_batch_end
 End Batch Loop
 - on_valid_end
End Valid

See Also

Other luz_callbacks: luz_callback_auto_resume(), luz_callback_csv_logger(), luz_callback_early_stopping(), luz_callback_interrupt(), luz_callback_keep_best_model(), luz_callback_lr_scheduler(), luz_callback_metrics(), luz_callback_mixup(), luz_callback_model_checkpoint(), luz_callback_profile(), luz_callback_progress(), luz_callback_resume_from_checkpoint(), luz_callback_train_valid()

Examples

print_callback <- luz_callback(
 name = "print_callback",
 on_train_batch_end = function() {
   cat("Iteration ", ctx$iter, "\n")
 },
 on_epoch_end = function() {
   cat("Done!\n")
 }
)

Resume training callback

Description

This callback allows you to resume training a model.

Usage

luz_callback_auto_resume(path = "./state.pt")

Arguments

Details

When using it, model weights, optimizer state are serialized at the end of each epoch. If something fails during training simply re-running the same script will restart the model training from the epoch right after the last epoch that was serialized.

Customizing serialization

By default model, optimizer state and records are serialized. Callbacks can be used to customize serialization by implementing the state_dict() and load_state_dict() methods. If those methods are implemented, then state_dict() is called at the end of each epoch and load_state_dict() is called when the model is resumed.

Note

In general you will want to add this callback as the last in the callbacks list, this way, the serialized state is likely to contain all possible changes that other callbacks could have made at 'on_epoch_end'. The default weight attribute of this callback is Inf.

Read the checkpointing article in the pkgdown website for more information.

See Also

Other luz_callbacks: luz_callback_csv_logger(), luz_callback_early_stopping(), luz_callback_interrupt(), luz_callback_keep_best_model(), luz_callback_lr_scheduler(), luz_callback_metrics(), luz_callback_mixup(), luz_callback_model_checkpoint(), luz_callback_profile(), luz_callback_progress(), luz_callback_resume_from_checkpoint(), luz_callback_train_valid(), luz_callback()

Examples

if (torch::torch_is_installed()) {
library(torch)
library(luz)

x <- torch_randn(1000, 10)
y <- torch_randn(1000, 1)

model <- nn_linear %>%
  setup(optimizer = optim_sgd, loss = nnf_mse_loss) %>%
  set_hparams(in_features = 10, out_features = 1) %>%
  set_opt_hparams(lr = 0.01)


# simulate a failure in the middle of epoch 5 happening only once.
callback_stop <- luz_callback(
  "interrupt",
  failed = FALSE,
  on_epoch_end = function() {
    if (ctx$epoch == 5 && !self$failed) {
      self$failed <- TRUE
      stop("Error on epoch 5")
    }
  }
)

path <- tempfile()
autoresume <- luz_callback_auto_resume(path = path)
interrupt <- callback_stop()

# try once and the model fails
try({
  results <- model %>% fit(
    list(x, y),
    callbacks = list(autoresume, interrupt),
    verbose = FALSE
  )
})

# model resumes and completes
results <- model %>% fit(
  list(x, y),
  callbacks = list(autoresume, interrupt),
  verbose = FALSE
)

get_metrics(results)

}

CSV logger callback

Description

Logs metrics obtained during training a fiel on disk. The file will have 1 line for each epoch/validation.

Usage

luz_callback_csv_logger(path)

Arguments

See Also

Other luz_callbacks: luz_callback_auto_resume(), luz_callback_early_stopping(), luz_callback_interrupt(), luz_callback_keep_best_model(), luz_callback_lr_scheduler(), luz_callback_metrics(), luz_callback_mixup(), luz_callback_model_checkpoint(), luz_callback_profile(), luz_callback_progress(), luz_callback_resume_from_checkpoint(), luz_callback_train_valid(), luz_callback()

Early stopping callback

Description

Stops training when a monitored metric stops improving

Usage

luz_callback_early_stopping(
  monitor = "valid_loss",
  min_delta = 0,
  patience = 0,
  mode = "min",
  baseline = NULL
)

Arguments

Value

A luz_callback that does early stopping.

Note

This callback adds a on_early_stopping callback that can be used to call callbacks as soon as the model stops training.

If verbose=TRUE in fit.luz_module_generator() a message is printed when early stopping.

See Also

Other luz_callbacks: luz_callback_auto_resume(), luz_callback_csv_logger(), luz_callback_interrupt(), luz_callback_keep_best_model(), luz_callback_lr_scheduler(), luz_callback_metrics(), luz_callback_mixup(), luz_callback_model_checkpoint(), luz_callback_profile(), luz_callback_progress(), luz_callback_resume_from_checkpoint(), luz_callback_train_valid(), luz_callback()

Examples

cb <- luz_callback_early_stopping()

Gradient clipping callback

Description

By adding the GradientClip callback, the gradient norm_type (default:2) norm is clipped to at most max_norm (default:1) using torch::nn_utils_clip_grad_norm_(), which can avoid loss divergence.

Usage

luz_callback_gradient_clip(max_norm = 1, norm_type = 2)

Arguments

References

See FastAI documentation for the GradientClip callback.

Interrupt callback

Description

Adds a handler that allows interrupting the training loop using ctrl + C. Also registers a on_interrupt breakpoint so users can register callbacks to be run on training loop interruption.

Usage

luz_callback_interrupt()

Value

A luz_callback

Note

In general you don't need to use these callback by yourself because it's always included by default in fit.luz_module_generator().

See Also

Other luz_callbacks: luz_callback_auto_resume(), luz_callback_csv_logger(), luz_callback_early_stopping(), luz_callback_keep_best_model(), luz_callback_lr_scheduler(), luz_callback_metrics(), luz_callback_mixup(), luz_callback_model_checkpoint(), luz_callback_profile(), luz_callback_progress(), luz_callback_resume_from_checkpoint(), luz_callback_train_valid(), luz_callback()

Examples

interrupt_callback <- luz_callback_interrupt()

Keep the best model

Description

Each epoch, if there's improvement in the monitored metric we serialize the model weights to a temp file. When training is done, we reload weights from the best model.

Usage

luz_callback_keep_best_model(
  monitor = "valid_loss",
  mode = "min",
  min_delta = 0
)

Arguments

See Also

Other luz_callbacks: luz_callback_auto_resume(), luz_callback_csv_logger(), luz_callback_early_stopping(), luz_callback_interrupt(), luz_callback_lr_scheduler(), luz_callback_metrics(), luz_callback_mixup(), luz_callback_model_checkpoint(), luz_callback_profile(), luz_callback_progress(), luz_callback_resume_from_checkpoint(), luz_callback_train_valid(), luz_callback()

Examples

cb <- luz_callback_keep_best_model()

Learning rate scheduler callback

Description

Initializes and runs torch::lr_scheduler()s.

Usage

luz_callback_lr_scheduler(
  lr_scheduler,
  ...,
  call_on = "on_epoch_end",
  opt_name = NULL
)

Arguments

Value

A luz_callback() generator.

See Also

Other luz_callbacks: luz_callback_auto_resume(), luz_callback_csv_logger(), luz_callback_early_stopping(), luz_callback_interrupt(), luz_callback_keep_best_model(), luz_callback_metrics(), luz_callback_mixup(), luz_callback_model_checkpoint(), luz_callback_profile(), luz_callback_progress(), luz_callback_resume_from_checkpoint(), luz_callback_train_valid(), luz_callback()

Examples

if (torch::torch_is_installed()) {
cb <- luz_callback_lr_scheduler(torch::lr_step, step_size = 30)
}

Metrics callback

Description

Tracks metrics passed to setup() during training and validation.

Usage

luz_callback_metrics()

Details

This callback takes care of 2 ctx attributes:

• ctx$metrics: stores the current metrics objects that are initialized once for epoch, and are further update()d and compute()d every batch. You will rarely need to work with these metrics.

• ctx$records$metrics: Stores metrics per training/validation and epoch. The structure is very similar to ctx$losses.

Value

A luz_callback

Note

In general you won't need to explicitly use the metrics callback as it's used by default in fit.luz_module_generator().

See Also

Other luz_callbacks: luz_callback_auto_resume(), luz_callback_csv_logger(), luz_callback_early_stopping(), luz_callback_interrupt(), luz_callback_keep_best_model(), luz_callback_lr_scheduler(), luz_callback_mixup(), luz_callback_model_checkpoint(), luz_callback_profile(), luz_callback_progress(), luz_callback_resume_from_checkpoint(), luz_callback_train_valid(), luz_callback()

Mixup callback

Description

Implementation of 'mixup: Beyond Empirical Risk Minimization'. As of today, tested only for categorical data, where targets are expected to be integers, not one-hot encoded vectors. This callback is supposed to be used together with nn_mixup_loss().

Usage

luz_callback_mixup(alpha = 0.4, ..., run_valid = FALSE, auto_loss = FALSE)

Arguments

Details

Overall, we follow the fastai implementation described here. Namely,

• We work with a single dataloader only, randomly mixing two observations from the same batch.

• We linearly combine losses computed for both targets: loss(output, new_target) = weight * loss(output, target1) + (1-weight) * loss(output, target2)

• We draw different mixing coefficients for every pair.

• We replace weight with weight = max(weight, 1-weight) to avoid duplicates.

Value

A luz_callback

See Also

nn_mixup_loss(), nnf_mixup()

Other luz_callbacks: luz_callback_auto_resume(), luz_callback_csv_logger(), luz_callback_early_stopping(), luz_callback_interrupt(), luz_callback_keep_best_model(), luz_callback_lr_scheduler(), luz_callback_metrics(), luz_callback_model_checkpoint(), luz_callback_profile(), luz_callback_progress(), luz_callback_resume_from_checkpoint(), luz_callback_train_valid(), luz_callback()

Examples

if (torch::torch_is_installed()) {
mixup_callback <- luz_callback_mixup()
}

Checkpoints model weights

Description

This saves checkpoints of the model according to the specified metric and behavior.

Usage

luz_callback_model_checkpoint(
  path,
  monitor = "valid_loss",
  save_best_only = FALSE,
  mode = "min",
  min_delta = 0
)

Arguments

Note

mode and min_delta are only used when save_best_only=TRUE. save_best_only will overwrite the saved models if the path parameter don't differentiate by epochs.

Read the checkpointing article in the pkgdown website for more information.

See Also

Other luz_callbacks: luz_callback_auto_resume(), luz_callback_csv_logger(), luz_callback_early_stopping(), luz_callback_interrupt(), luz_callback_keep_best_model(), luz_callback_lr_scheduler(), luz_callback_metrics(), luz_callback_mixup(), luz_callback_profile(), luz_callback_progress(), luz_callback_resume_from_checkpoint(), luz_callback_train_valid(), luz_callback()

Examples

luz_callback_model_checkpoint(path= "path/to/dir")
luz_callback_model_checkpoint(path= "path/to/dir/epoch-{epoch:02d}/model.pt")
luz_callback_model_checkpoint(path= "path/to/dir/epoch-{epoch:02d}/model-{monitor:.2f}.pt")

Profile callback

Description

Computes the times for high-level operations in the training loops.

Usage

luz_callback_profile()

Details

Records are saved in ctx$records$profile. Times are stored as seconds. Data is stored in the following structure:

• fit time for the entire fit procedure.

• epoch times per epoch

Value

A luz_callback

Note

In general you don't need to use these callback by yourself because it's always included by default in fit.luz_module_generator().

See Also

Other luz_callbacks: luz_callback_auto_resume(), luz_callback_csv_logger(), luz_callback_early_stopping(), luz_callback_interrupt(), luz_callback_keep_best_model(), luz_callback_lr_scheduler(), luz_callback_metrics(), luz_callback_mixup(), luz_callback_model_checkpoint(), luz_callback_progress(), luz_callback_resume_from_checkpoint(), luz_callback_train_valid(), luz_callback()

Examples

profile_callback <- luz_callback_profile()

Progress callback

Description

Responsible for printing progress during training.

Usage

luz_callback_progress()

Value

A luz_callback

Note

In general you don't need to use these callback by yourself because it's always included by default in fit.luz_module_generator().

Printing can be disabled by passing verbose=FALSE to fit.luz_module_generator().

See Also

Other luz_callbacks: luz_callback_auto_resume(), luz_callback_csv_logger(), luz_callback_early_stopping(), luz_callback_interrupt(), luz_callback_keep_best_model(), luz_callback_lr_scheduler(), luz_callback_metrics(), luz_callback_mixup(), luz_callback_model_checkpoint(), luz_callback_profile(), luz_callback_resume_from_checkpoint(), luz_callback_train_valid(), luz_callback()

Allow resume model training from a specific checkpoint

Description

Allow resume model training from a specific checkpoint

Usage

luz_callback_resume_from_checkpoint(
  path,
  ...,
  restore_model_state = TRUE,
  restore_records = FALSE,
  restore_optimizer_state = FALSE,
  restore_callbacks_state = FALSE
)

Arguments

Note

Read the checkpointing article in the pkgdown website for more information.

See Also

luz_callback_model_checkpoint()

Other luz_callbacks: luz_callback_auto_resume(), luz_callback_csv_logger(), luz_callback_early_stopping(), luz_callback_interrupt(), luz_callback_keep_best_model(), luz_callback_lr_scheduler(), luz_callback_metrics(), luz_callback_mixup(), luz_callback_model_checkpoint(), luz_callback_profile(), luz_callback_progress(), luz_callback_train_valid(), luz_callback()

tfevents callback

Description

Logs metrics and other model information in the tfevents file format. Assuming tensorboard is installed, result can be visualized with

Usage

luz_callback_tfevents(logdir = "logs", histograms = FALSE, ...)

Arguments

Details

tensorboard --logdir=logs

Examples

if (torch::torch_is_installed()) {
library(torch)
x <- torch_randn(1000, 10)
y <- torch_randn(1000, 1)

model <- nn_linear %>%
  setup(loss = nnf_mse_loss, optimizer = optim_adam) %>%
  set_hparams(in_features = 10, out_features = 1) %>%
  set_opt_hparams(lr = 1e-4)

tmp <- tempfile()

model %>% fit(list(x, y), valid_data = 0.2, callbacks = list(
  luz_callback_tfevents(tmp, histograms = TRUE)
))
}

Train-eval callback

Description

Switches important flags for training and evaluation modes.

Usage

luz_callback_train_valid()

Details

It takes care of the three ctx attributes:

• ctx$model: Responsible for calling ctx$model$train() and ctx$model$eval(), when appropriate.

• ctx$training: Sets this flag to TRUE when training and FALSE when in validation mode.

• ctx$loss: Resets the loss attribute to list() when finished training/ or validating.

Value

A luz_callback

Note

In general you won't need to explicitly use the metrics callback as it's used by default in fit.luz_module_generator().

See Also

Other luz_callbacks: luz_callback_auto_resume(), luz_callback_csv_logger(), luz_callback_early_stopping(), luz_callback_interrupt(), luz_callback_keep_best_model(), luz_callback_lr_scheduler(), luz_callback_metrics(), luz_callback_mixup(), luz_callback_model_checkpoint(), luz_callback_profile(), luz_callback_progress(), luz_callback_resume_from_checkpoint(), luz_callback()

Load trained model

Description

Loads a fitted model. See documentation in luz_save().

Usage

luz_load(path)

Arguments

See Also

Other luz_save: luz_save()

Loads a checkpoint

Description

Works with checkpoints created typically with luz_callback_model_checkpoint().

Usage

luz_load_checkpoint(obj, path, ...)

Arguments

Loads model weights into a fitted object.

Description

This can be useful when you have saved model checkpoints during training and want to reload the best checkpoint in the end.

Usage

luz_load_model_weights(obj, path, ...)

luz_save_model_weights(obj, path)

Arguments

Value

Returns NULL invisibly.

Warning

luz_save_model_weights operates inplace, ie modifies the model object to contain the new weights.

Creates a new luz metric

Description

Creates a new luz metric

Usage

luz_metric(
  name = NULL,
  ...,
  private = NULL,
  active = NULL,
  parent_env = parent.frame(),
  inherit = NULL
)

Arguments

Details

In order to implement a new luz_metric we need to implement 3 methods:

• initialize: defines the metric initial state. This function is called for each epoch for both training and validation loops.

• update: updates the metric internal state. This function is called at every training and validation step with the predictions obtained by the model and the target values obtained from the dataloader.

• compute: uses the internal state to compute metric values. This function is called whenever we need to obtain the current metric value. Eg, it’s called every training step for metrics displayed in the progress bar, but only called once per epoch to record it’s value when the progress bar is not displayed.

Optionally, you can implement an abbrev field that gives the metric an abbreviation that will be used when displaying metric information in the console or tracking record. If no abbrev is passed, the class name will be used.

Let’s take a look at the implementation of luz_metric_accuracy so you can see how to implement a new one:

luz_metric_accuracy <- luz_metric(
  # An abbreviation to be shown in progress bars, or 
  # when printing progress
  abbrev = "Acc", 
  # Initial setup for the metric. Metrics are initialized
  # every epoch, for both training and validation
  initialize = function() {
    self$correct <- 0
    self$total <- 0
  },
  # Run at every training or validation step and updates
  # the internal state. The update function takes `preds`
  # and `target` as parameters.
  update = function(preds, target) {
    pred <- torch::torch_argmax(preds, dim = 2)
    self$correct <- self$correct + (pred == target)$
      to(dtype = torch::torch_float())$
      sum()$
      item()
    self$total <- self$total + pred$numel()
  },
  # Use the internal state to query the metric value
  compute = function() {
    self$correct/self$total
  }
)

Note: It’s good practice that the compute metric returns regular R values instead of torch tensors and other parts of luz will expect that.

Value

Returns new luz metric.

See Also

Other luz_metrics: luz_metric_accuracy(), luz_metric_binary_accuracy_with_logits(), luz_metric_binary_accuracy(), luz_metric_binary_auroc(), luz_metric_mae(), luz_metric_mse(), luz_metric_multiclass_auroc(), luz_metric_rmse()

Examples

luz_metric_accuracy <- luz_metric(
  # An abbreviation to be shown in progress bars, or
  # when printing progress
  abbrev = "Acc",
  # Initial setup for the metric. Metrics are initialized
  # every epoch, for both training and validation
  initialize = function() {
    self$correct <- 0
    self$total <- 0
  },
  # Run at every training or validation step and updates
  # the internal state. The update function takes `preds`
  # and `target` as parameters.
  update = function(preds, target) {
    pred <- torch::torch_argmax(preds, dim = 2)
    self$correct <- self$correct + (pred == target)$
      to(dtype = torch::torch_float())$
      sum()$
      item()
    self$total <- self$total + pred$numel()
  },
  # Use the internal state to query the metric value
  compute = function() {
    self$correct/self$total
  }
)

Accuracy

Description

Computes accuracy for multi-class classification problems.

Usage

luz_metric_accuracy()

Details

This metric expects to take logits or probabilities at every update. It will then take the columnwise argmax and compare to the target.

Value

Returns new luz metric.

See Also

Other luz_metrics: luz_metric_binary_accuracy_with_logits(), luz_metric_binary_accuracy(), luz_metric_binary_auroc(), luz_metric_mae(), luz_metric_mse(), luz_metric_multiclass_auroc(), luz_metric_rmse(), luz_metric()

Examples

if (torch::torch_is_installed()) {
library(torch)
metric <- luz_metric_accuracy()
metric <- metric$new()
metric$update(torch_randn(100, 10), torch::torch_randint(1, 10, size = 100))
metric$compute()
}

Binary accuracy

Description

Computes the accuracy for binary classification problems where the model returns probabilities. Commonly used when the loss is torch::nn_bce_loss().

Usage

luz_metric_binary_accuracy(threshold = 0.5)

Arguments

Value

Returns new luz metric.

See Also

Other luz_metrics: luz_metric_accuracy(), luz_metric_binary_accuracy_with_logits(), luz_metric_binary_auroc(), luz_metric_mae(), luz_metric_mse(), luz_metric_multiclass_auroc(), luz_metric_rmse(), luz_metric()

Examples

if (torch::torch_is_installed()) {
library(torch)
metric <- luz_metric_binary_accuracy(threshold = 0.5)
metric <- metric$new()
metric$update(torch_rand(100), torch::torch_randint(0, 1, size = 100))
metric$compute()
}

Binary accuracy with logits

Description

Computes accuracy for binary classification problems where the model return logits. Commonly used together with torch::nn_bce_with_logits_loss().

Usage

luz_metric_binary_accuracy_with_logits(threshold = 0.5)

Arguments

Details

Probabilities are generated using torch::nnf_sigmoid() and threshold is used to classify between 0 or 1.

Value

Returns new luz metric.

See Also

Other luz_metrics: luz_metric_accuracy(), luz_metric_binary_accuracy(), luz_metric_binary_auroc(), luz_metric_mae(), luz_metric_mse(), luz_metric_multiclass_auroc(), luz_metric_rmse(), luz_metric()

Examples

if (torch::torch_is_installed()) {
library(torch)
metric <- luz_metric_binary_accuracy_with_logits(threshold = 0.5)
metric <- metric$new()
metric$update(torch_randn(100), torch::torch_randint(0, 1, size = 100))
metric$compute()
}

Computes the area under the ROC

Description

To avoid storing all predictions and targets for an epoch we compute confusion matrices across a range of pre-established thresholds.

Usage

luz_metric_binary_auroc(
  num_thresholds = 200,
  thresholds = NULL,
  from_logits = FALSE
)

Arguments

See Also

Other luz_metrics: luz_metric_accuracy(), luz_metric_binary_accuracy_with_logits(), luz_metric_binary_accuracy(), luz_metric_mae(), luz_metric_mse(), luz_metric_multiclass_auroc(), luz_metric_rmse(), luz_metric()

Examples

if (torch::torch_is_installed()){
library(torch)
actual <- c(1, 1, 1, 0, 0, 0)
predicted <- c(0.9, 0.8, 0.4, 0.5, 0.3, 0.2)

y_true <- torch_tensor(actual)
y_pred <- torch_tensor(predicted)

m <- luz_metric_binary_auroc(thresholds = predicted)
m <- m$new()

m$update(y_pred[1:2], y_true[1:2])
m$update(y_pred[3:4], y_true[3:4])
m$update(y_pred[5:6], y_true[5:6])

m$compute()
}

Mean absolute error

Description

Computes the mean absolute error.

Usage

luz_metric_mae()

Value

Returns new luz metric.

See Also

Other luz_metrics: luz_metric_accuracy(), luz_metric_binary_accuracy_with_logits(), luz_metric_binary_accuracy(), luz_metric_binary_auroc(), luz_metric_mse(), luz_metric_multiclass_auroc(), luz_metric_rmse(), luz_metric()

Examples

if (torch::torch_is_installed()) {
library(torch)
metric <- luz_metric_mae()
metric <- metric$new()
metric$update(torch_randn(100), torch_randn(100))
metric$compute()
}

Mean squared error

Description

Computes the mean squared error

Usage

luz_metric_mse()

Value

A luz_metric object.

See Also

Other luz_metrics: luz_metric_accuracy(), luz_metric_binary_accuracy_with_logits(), luz_metric_binary_accuracy(), luz_metric_binary_auroc(), luz_metric_mae(), luz_metric_multiclass_auroc(), luz_metric_rmse(), luz_metric()

Computes the multi-class AUROC

Description

The same definition as Keras is used by default. This is equivalent to the 'micro' method in SciKit Learn too. See docs.

Usage

luz_metric_multiclass_auroc(
  num_thresholds = 200,
  thresholds = NULL,
  from_logits = FALSE,
  average = c("micro", "macro", "weighted", "none")
)

Arguments

Details

Note that class imbalance can affect this metric unlike the AUC for binary classification.

Currently the AUC is approximated using the 'interpolation' method described in Keras.

See Also

Other luz_metrics: luz_metric_accuracy(), luz_metric_binary_accuracy_with_logits(), luz_metric_binary_accuracy(), luz_metric_binary_auroc(), luz_metric_mae(), luz_metric_mse(), luz_metric_rmse(), luz_metric()

Examples

if (torch::torch_is_installed()) {
library(torch)
actual <- c(1, 1, 1, 0, 0, 0) + 1L
predicted <- c(0.9, 0.8, 0.4, 0.5, 0.3, 0.2)
predicted <- cbind(1-predicted, predicted)

y_true <- torch_tensor(as.integer(actual))
y_pred <- torch_tensor(predicted)

m <- luz_metric_multiclass_auroc(thresholds = as.numeric(predicted),
                                 average = "micro")
m <- m$new()

m$update(y_pred[1:2,], y_true[1:2])
m$update(y_pred[3:4,], y_true[3:4])
m$update(y_pred[5:6,], y_true[5:6])
m$compute()
}

Root mean squared error

Description

Computes the root mean squared error.

Usage

luz_metric_rmse()

Value

Returns new luz metric.

See Also

Other luz_metrics: luz_metric_accuracy(), luz_metric_binary_accuracy_with_logits(), luz_metric_binary_accuracy(), luz_metric_binary_auroc(), luz_metric_mae(), luz_metric_mse(), luz_metric_multiclass_auroc(), luz_metric()

Creates a metric set

Description

A metric set can be used to specify metrics that are only evaluated during training, validation or both.

Usage

luz_metric_set(metrics = NULL, train_metrics = NULL, valid_metrics = NULL)

Arguments

Saves luz objects to disk

Description

Allows saving luz fitted models to the disk. Objects can be loaded back with luz_load().

Usage

luz_save(obj, path, ...)

Arguments

Warning

The ctx is naively serialized. Ie, we only use saveRDS() to serialize it. Don't expect luz_save to work correctly if you have unserializable objects in the ctx like torch_tensors and external pointers in general.

Note

Objects are saved as plain .rds files but obj$model is serialized with torch_save before saving it.

See Also

Other luz_save: luz_load()

Loss to be used with callbacks_mixup().

Description

In the training phase, computes individual losses with regard to two targets, weights them item-wise, and averages the linear combinations to yield the mean batch loss. For validation and testing, defers to the passed-in loss.

Usage

nn_mixup_loss(loss)

Arguments

Details

It should be used together with luz_callback_mixup().

See Also

luz_callback_mixup()

Mixup logic

Description

Logic underlying luz_callback_mixup().

Usage

nnf_mixup(x, y, weight)

Arguments

Details

Based on the passed-in input and target batches, as well as applicable mixing weights, we return new tensors intended to replace the current batch. The new input batch is a weighted linear combination of input batch items, while the new target batch bundles the original targets, as well as the mixing weights, in a nested list.

Value

A list of:

• x, the new, mixed-up input batch

• y, a list of:

  • ys, a list of:

    • y1, the original target y1

    • y2, the mixed-in target y2

  • weight, the mixing weights

See Also

luz_callback_mixup()

Examples

if (torch::torch_is_installed()) {
batch_x <- torch::torch_randn(c(10, 768))
batch_y <- torch::torch_randn(10)
weight <- torch::torch_tensor(rep(0.9, 10))$view(c(10, 1))
nnf_mixup(batch_x, batch_y, weight)
}

Create predictions for a fitted model

Description

Create predictions for a fitted model

Usage

## S3 method for class 'luz_module_fitted'
predict(
  object,
  newdata,
  ...,
  callbacks = list(),
  accelerator = NULL,
  verbose = NULL,
  dataloader_options = NULL
)

Arguments

See Also

Other training: evaluate(), fit.luz_module_generator(), setup()

Objects exported from other packages

Description

These objects are imported from other packages. Follow the links below to see their documentation.

generics

fit

Set hyper-parameter of a module

Description

This function is used to define hyper-parameters before calling fit for luz_modules.

Usage

set_hparams(module, ...)

Arguments

Value

The same luz module

See Also

Other set_hparam: set_opt_hparams()

Set optimizer hyper-parameters

Description

This function is used to define hyper-parameters for the optimizer initialization method.

Usage

set_opt_hparams(module, ...)

Arguments

Value

The same luz module

See Also

Other set_hparam: set_hparams()

Set's up a nn_module to use with luz

Description

The setup function is used to set important attributes and method for nn_modules to be used with luz.

Usage

setup(module, loss = NULL, optimizer = NULL, metrics = NULL, backward = NULL)

Arguments

Details

It makes sure the module have all the necessary ingredients in order to be fitted.

Value

A luz module that can be trained with fit().

Note

It also adds a device active field that can be used to query the current module device within methods, with eg self$device. This is useful when ctx() is not available, eg, when calling methods from outside the luz wrappers. Users can override the default by implementing a device active method in the input module.

See Also

Other training: evaluate(), fit.luz_module_generator(), predict.luz_module_fitted()