bbotk (version 1.5.0)

callback_batch: Create Batch Optimization Callback

Description

Function to create a CallbackBatch.

Optimization callbacks can be called from different stages of optimization process. The stages are prefixed with on_*.

Start Optimization
     - on_optimization_begin
    Start Optimizer Batch
         - on_optimizer_before_eval
         - on_optimizer_after_eval
    End Optimizer Batch
     - on_result_begin
     - on_result_end
     - on_optimization_end
End Optimization

See also the section on parameters for more information on the stages. A optimization callback works with ContextBatch.

Usage

callback_batch(
  id,
  label = NA_character_,
  man = NA_character_,
  on_optimization_begin = NULL,
  on_optimizer_before_eval = NULL,
  on_optimizer_after_eval = NULL,
  on_result_begin = NULL,
  on_result_end = NULL,
  on_result = NULL,
  on_optimization_end = NULL
)

Arguments

id

(character(1))
Identifier for the new instance.

label

(character(1))
Label for the new instance.

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().

on_optimization_begin

(function())
Stage called at the beginning of the optimization. Called in Optimizer$optimize(). The functions must have two arguments named callback and context.

on_optimizer_before_eval

(function())
Stage called after the optimizer proposes points. Called in OptimInstance$eval_batch(). The functions must have two arguments named callback and context. The argument of $eval_batch(xdt) is available in context.

on_optimizer_after_eval

(function())
Stage called after points are evaluated. Called in OptimInstance$eval_batch(). The functions must have two arguments named callback and context. The new points and outcomes in instance$archive are available in context.

on_result_begin

(function())
Stage called before result are written to the instance. Called in OptimInstance$assign_result(). The functions must have two arguments named callback and context. The arguments of $assign_result(xdt, y, extra) are available in context.

on_result_end

(function())
Stage called after result are written to the instance. Called in OptimInstance$assign_result(). The functions must have two arguments named callback and context. The final result instance$result is available in context.

on_result

(function())
Deprecated. Use on_result_end instead. Stage called after result are written. Called in OptimInstance$assign_result(). The functions must have two arguments named callback and context.

on_optimization_end

(function())
Stage called at the end of the optimization. Called in Optimizer$optimize(). The functions must have two arguments named callback and context.

Details

A callback can write data to its state ($state), e.g. settings that affect the callback itself. The ContextBatch allows to modify the instance, archive, optimizer and final result.

Examples

# write archive to disk
callback_batch("bbotk.backup",
  on_optimization_end = function(callback, context) {
    saveRDS(context$instance$archive, "archive.rds")
  }
)