Better printing of internal tuned values for logging

[sebffischer]

Because the internal_tuned_values are a list column, one cannot see their values by looking at the logging output, see the example below:

  library(mlr3verse)
#> Loading required package: mlr3
  learner = lrn("classif.debug",
    iter = to_tune(upper = 1000L, internal = TRUE),
    x = to_tune(0.2, 0.3),
    validate = 0.3,
    early_stopping = TRUE
  )
  ti = tune(
    tuner = tnr("grid_search", batch_size = 2),
    learner = learner,
    task = tsk("iris"),
    resampling = rsmp("holdout"),
    term_evals = 4
  )
#> INFO  [12:38:00.562] [bbotk] Starting to optimize 1 parameter(s) with '<OptimizerBatchGridSearch>' and '<TerminatorEvals> [n_evals=4, k=0]'
#> INFO  [12:38:00.579] [bbotk] Evaluating 2 configuration(s)
#> INFO  [12:38:00.587] [mlr3] Running benchmark with 2 resampling iterations
#> INFO  [12:38:00.607] [mlr3] Applying learner 'classif.debug' on task 'iris' (iter 1/1)
#> INFO  [12:38:00.621] [mlr3] Applying learner 'classif.debug' on task 'iris' (iter 1/1)
#> INFO  [12:38:00.637] [mlr3] Finished benchmark
#> INFO  [12:38:00.658] [bbotk] Result of batch 1:
#> INFO  [12:38:00.660] [bbotk]          x classif.ce warnings errors runtime_learners internal_tuned_values
#> INFO  [12:38:00.660] [bbotk]  0.2000000       0.74        0      0            0.004             <list[1]>
#> INFO  [12:38:00.660] [bbotk]  0.2555556       0.56        0      0            0.003             <list[1]>
#> INFO  [12:38:00.660] [bbotk]                                 uhash
#> INFO  [12:38:00.660] [bbotk]  1036ef04-e06a-4c15-adc4-fe58e53c8c9f
#> INFO  [12:38:00.660] [bbotk]  a8e95113-68ac-41e6-9eb5-0abdc282dbd3
#> INFO  [12:38:00.661] [bbotk] Evaluating 2 configuration(s)
#> INFO  [12:38:00.665] [mlr3] Running benchmark with 2 resampling iterations
#> INFO  [12:38:00.667] [mlr3] Applying learner 'classif.debug' on task 'iris' (iter 1/1)
#> INFO  [12:38:00.678] [mlr3] Applying learner 'classif.debug' on task 'iris' (iter 1/1)
#> INFO  [12:38:00.687] [mlr3] Finished benchmark
#> INFO  [12:38:00.709] [bbotk] Result of batch 2:
#> INFO  [12:38:00.710] [bbotk]          x classif.ce warnings errors runtime_learners internal_tuned_values
#> INFO  [12:38:00.710] [bbotk]  0.2333333       0.70        0      0            0.001             <list[1]>
#> INFO  [12:38:00.710] [bbotk]  0.2666667       0.74        0      0            0.001             <list[1]>
#> INFO  [12:38:00.710] [bbotk]                                 uhash
#> INFO  [12:38:00.710] [bbotk]  c2a54ca1-8684-441b-9349-297090141638
#> INFO  [12:38:00.710] [bbotk]  2ed86023-845e-4922-bdd7-4d3f52b68973
#> INFO  [12:38:00.719] [bbotk] Finished optimizing after 4 evaluation(s)
#> INFO  [12:38:00.719] [bbotk] Result:
#> INFO  [12:38:00.720] [bbotk]          x internal_tuned_values learner_param_vals  x_domain classif.ce
#> INFO  [12:38:00.720] [bbotk]      <num>                <list>             <list>    <list>      <num>
#> INFO  [12:38:00.720] [bbotk]  0.2555556             <list[1]>          <list[3]> <list[1]>       0.56

^{Created on 2025-01-21 with reprex v2.1.1}

It would be nice if the internal_tuned_values column hat a custom printer that actually prints the values and list <list[1]>

[be-marc]

Thanks. Done via custom printer #489