Provide a scope with mappings of names to custom objects

Provide a scope with mappings of names to custom objects

with_custom_object_scope(objects, expr)

Arguments

objects	Named list of objects
expr	Expression to evaluate

Details

There are many elements of Keras models that can be customized with user objects (e.g. losses, metrics, regularizers, etc.). When loading saved models that use these functions you typically need to explicitily map names to user objects via the custom_objects parmaeter.

The with_custom_object_scope() function provides an alternative that lets you create a named alias for a user object that applies to an entire block of code, and is automatically recognized when loading saved models.

Examples

# NOT RUN {
# define custom metric
metric_top_3_categorical_accuracy <-
  custom_metric("top_3_categorical_accuracy", function(y_true, y_pred) {
    metric_top_k_categorical_accuracy(y_true, y_pred, k = 3)
  })

with_custom_object_scope(c(top_k_acc = sparse_top_k_cat_acc), {

  # ...define model...

  # compile model (refer to "top_k_acc" by name)
  model %>% compile(
    loss = "binary_crossentropy",
    optimizer = optimizer_nadam(),
    metrics = c("top_k_acc")
  )

  # save the model
  save_model_hdf5("my_model.h5")

  # loading the model within the custom object scope doesn't
  # require explicitly providing the custom_object
  load_model_hdf5("my_model.h5")
})
# }