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Changelog

Source: NEWS.md

mlr3 (development version)

  • feat: Learner$predict() can now add additional data to PredictionClassif and PredictionRegr objects via the extra field.

mlr3 1.2.0

CRAN release: 2025-09-13

  • feat: Add mirai support for parallelization and encapsulation.
  • feat: Fallback can now be configured to only be used in case of certain errors via the when argument.
  • feat: Custom error and warning classes.
  • fix: $selected_features returns error when model is not trained yet.
  • docs: Missing values during scoring.
  • BREAKING CHANGE: Removed data_format argument of $data() method of DataBackend.
  • BREAKING CHANGE: Remove data_formats field from Learner.
  • BREAKING CHANGE: Remove DataBackendMatrix class.
  • feat: Add materialize_view() method to Task to replace the internal DataBackend with a new one after operations like $select() and $filter().
  • docs: Information about quantile prediction.
  • perf: Use fget in assert_predictable.
  • feat: Store oob error in state without requiring storing the model.
  • fix: $levels() of Task returns in the correct order.
  • chore: Only print up to 10 classes in the Task printer.
  • fix: Check if quantiles and quantile_response are set.

mlr3 1.1.0

CRAN release: 2025-07-30

  • feat: Add new measure MeasureRegrRQR for quantile regression.
  • feat: Add $predict_newdata_fast() method to Learner to speed up prediction.
  • fix: configure_learner is passed on run_experiment() for autotest learners.

mlr3 1.0.1

CRAN release: 2025-07-03

  • fix: The printer of Learner failed when the validate field was set.
  • fix: Avoid printing empty line for feature less tasks.
  • perf: Use data.table::setattr() for less copying.

mlr3 1.0.0

CRAN release: 2025-06-18

  • BREAKING CHANGE: The mlr3 ecosystem has a base logger now which is named mlr3. The mlr3/core logger is a child of the mlr3 logger and is used for logging messages from the mlr3 package. Some extension packages have their own loggers which are children of the mlr3 logger e.g. mlr3/mlr3pipelines and mlr3/bbotk for tuning.

  • BREAKING CHANGE: weights property and functionality is split into weights_learner and weights_measure:

    • weights_learner: Weights used during training by the Learner.
    • weights_measure: Weights used during scoring predictions via measures.

    Each of these can be disabled via the new field use_weights in Learner and Measure objects.

  • feat: Add $confusion_weighted field to PredictionClassif.

  • feat: Add $weights field to Prediction. It contains the weights_measure weights from the Task that was used for prediction.

  • feat: Add "macro_weighted" option to Measure$average field.

  • feat: MeasureRegrRSQ and MeasureClassifCost gain "weights" property.

  • feat: LearnerClassifFeatureless, LearnerRegrFeatureless, LearnerClassifDebug, LearnerRegrDebug gain "weights" property.

  • feat: Learner printer now prints information about encapsulation and weights use.

  • feat: Add score_roc_measures() to score a prediction on various roc measures.

  • feat: A better error message is thrown, which often happens when incorrectly configuring the validate field of a GraphLearner

  • feat: Added method $set_threshold() to BenchmarkResult and ResamplingResult, which allows to set the threshold for the response prediction of classification learners, given they have output a probability prediction (#1270).

  • feat: Added field $uhash_table to BenchmarkResult and functions uhash() and uhashes() to easily compute uhashes for given learner, task, or resampling ids (#1270).

  • feat: You can now change the default predict type of classification learners to "prob" by setting the option mlr3.prob_as_default to TRUE (#1273).

  • feat: benchmark_grid() will now throw a warning if you mix different predict types in the design (#1273).

  • feat: Converting a BenchmarkResult to a data.table now includes the task_id, learner_id, and resampling_id columns (#1275).

  • fix: Add missing parameters for "regr.pinball" and "sim.phi" measures.

  • feat: Add new measure "regr.rqr" for quantile regression.

mlr3 0.23.0

CRAN release: 2025-03-12

  • feat: Add new col_role offset in Task and offset Learner property. A warning is produced if a learner that doesn’t support offsets is trained with a task that has an offset column.
  • fix: The $predict_newdata() method of Learner now automatically conducts type conversions (#685).
  • BREAKING_CHANGE: Predicting on a Task with the wrong column information is now an error and not a warning.
  • Column names with UTF-8 characters are now allowed by default. The option mlr3.allow_utf8_names is removed.
  • BREAKING CHANGE: Learner$predict_types is read-only now.
  • docs: Clear up behavior of Learner$predict_type after training.
  • feat: Add callbacks to resample() and benchmark().
  • fix: Internal tuning and validation now works when the model requires marshaling (#1256)

mlr3 0.22.1

CRAN release: 2024-11-27

mlr3 0.22.0

CRAN release: 2024-11-24

  • fix: Quantiles must not ascend with probabilities.
  • refactor: Replace tsk("boston_housing") with tsk("california_housing").
  • feat: Require unique learner ids in benchmark_grid().
  • BREAKING CHANGE: Remove $loglik() method from all learners.
  • fix: Ignore future.globals.maxSize when future::plan("sequential") is used.
  • feat: Add $characteristics field to Task to store additional information.

mlr3 0.21.1

CRAN release: 2024-10-18

  • feat: Throw warning when prediction and measure type do not match.
  • fix: The mlr_reflections were broken when an extension package was not loaded on the workers. Extension packages must now register themselves in the mlr_reflections$loaded_packages field.

mlr3 0.21.0

CRAN release: 2024-09-24

  • BREAKING CHANGE: Deprecated data_format and data_formats for Learner, Task, and DataBackend classes.
  • feat: The partition() function creates training, test and validation sets now.
  • perf: Optimize the runtime of fixing factor levels.
  • perf: Optimize the runtime of setting row roles.
  • perf: Optimize the runtime of marshalling.
  • perf: Optimize the runtime of Task$col_info.
  • fix: column info is now checked for compatibility during Learner$predict (#943).
  • BREAKING CHANGE: The predict time of the learner now stores the cumulative duration for all predict sets (#992).
  • feat: $internal_valid_task can now be set to an integer vector.
  • feat: Measures can now have an empty $predict_sets (#1094). This is relevant for measures that only extract information from the model of a learner (such as internal validation scores or AIC / BIC)
  • BREAKING CHANGE: Deprecated the $divide() method
  • fix: Task$cbind() now works with non-standard primary keys for data.frames (#961).
  • fix: Triggering of fallback learner now has log-level "info" instead of "debug" (#972).
  • feat: Added new measure regr.pinball here and in mlr3measures.
  • feat: Added new measure mu_auc here and in mlr3measures.
  • feat: Add option to calculate the mean of the true values on the train set in msr("regr.rsq").
  • feat: Default fallback learner is set when encapsulation is activated.
  • feat: Learners classif.debug and regr.debug have new methods $importance() and $selected_features() for testing, also in downstream packages.
  • feat: Create default fallback learner with default_fallback().
  • feat: Check column roles when using $set_col_roles() and $col_roles.
  • fix: Add predict set to learner hash.
  • BREAKING CHANGE: Encapsulation and the fallback learner are now set with the $encapsulate(method, fallback) method. The $fallback field is read-only now and the encapsulate status can be retrieved from the $encapsulation field.

mlr3 0.20.2

CRAN release: 2024-07-29

  • refactor: Move RhpcBLASctl to suggest.
  • feat: Added resampling property "primary_iters"
  • feat: Added possibility to access observation-wise losses via function $obs_loss. This is possible for Prediction, ResampleResult and BenchmarkResult.
  • feat: Measures now also return a vector of numerics.

mlr3 0.20.1

CRAN release: 2024-07-22

  • feat: Add multiclass Matthews correlation coefficient msr("classif.mcc").

mlr3 0.20.0

CRAN release: 2024-06-28

  • Added support for learner-internal validation and tuning.

mlr3 0.19.0

CRAN release: 2024-04-24

  • Added support for "marshal" property, which allows learners to process models so they can be serialized. This happens automatically during resample() and benchmark().
  • Encapsulation methods use the same RNG state now.
  • Fix missing values in default_values.Learner() function.
  • Encapsulated error messages are now printed with the lgr package.

mlr3 0.18.0

CRAN release: 2024-03-05

  • Prepare compatibility with new paradox version.
  • Dictionary conversion of mlr_learners respects prototype arguments recently added in mlr3misc.
  • Skip unnecessary clone of learner’s state in resample().

mlr3 0.17.2

CRAN release: 2024-01-09

  • Skip new data.table tests on mac.

mlr3 0.17.1

CRAN release: 2023-12-21

  • Remove data_prototype when resampling from learner$state to reduce memory consumption.
  • Reduce number of threads used by data.table and BLAS to 1 when running resample() or benchmark() in parallel.
  • Optimize runtime of resample() and benchmark() by reducing the number of hashing operations.

mlr3 0.17.0

CRAN release: 2023-11-17

  • Learners cannot be added to the HotstartStack anymore when the model is missing.
  • Learners bellow the hotstart_threshold are not added to the HotstartStack anymore.
  • The learner$state$train_time in hotstarted learners is now only the time of the last training.
  • Added debug messages to the hotstart stack.
  • Fixed bug where the HotstartStack did not work with column roles set in the task.
  • The design of benchmark() can now include parameter settings.
  • Speed up resampling by removing unnecessary calls to packageVersion().
  • Fix boston housing data set.
  • Export generic function col_info to allow adding new methods for backends.
  • Task printer includes row roles now.
  • Add "mlr3.exec_chunk_bins" option to split the resampling iterations into a number of bins.

mlr3 0.16.1

CRAN release: 2023-06-17

  • Function data.table() is now re-exported.
  • Fixed a test which randomly failed.
  • Improved documentation.
  • Add encapsulation mode "try", which works similar to "none" but captures errors

mlr3 0.16.0

CRAN release: 2023-05-05

  • Added argument paired to benchmark_grid() function, which can be used to create a benchmark design, where resamplings have been instantiated on tasks.
  • Added S3 method for ResultData for as_resample_result() converter.
  • Added S3 method for list for as_resample_result() converter.
  • The featureless classification learner now returns proper probabilities (#918).

mlr3 0.15.0

CRAN release: 2023-03-17

  • Many returned tables are now assigned a class for a print method to make the output more readable.
  • Fixed some typos

mlr3 0.14.1

CRAN release: 2022-11-02

mlr3 0.14.0

CRAN release: 2022-08-11

  • Added multiclass measures: mauc_aunu, mauc_aunp, mauc_au1u, mauc_au1p.
  • Measure classif.costs does not require a Task anymore.
  • New converter: as_task_unsupervised()
  • Refactored the task types in mlr_reflections.

mlr3 0.13.4

CRAN release: 2022-07-21

  • Added new options for parallelization ("mlr3.exec_random" and "mlr3.exec_chunk_size"). These options are passed down to the respective map functions in package future.apply.
  • Fixed runtime measures depending on specific predict types (#832).
  • Added head() and tail() methods for Task.
  • Improved printing of multiple objects.

mlr3 0.13.3

CRAN release: 2022-03-01

  • Most objects now have a new (optional) field label, i.e. Task, TaskGenerator, Learner, Resampling, and Measure.
  • as.data.table() methods for objects of class Dictonary have been extended with additional columns.
  • as_task_classif.formula() and as_task_regr.formula() now remove additional atrributes attached to the data which caused some some learners to break.
  • Packages are now loaded prior to calling the $train() and $predict() methods of a Learner. This ensures that package loading errors are properly propagated and not affected by encapsulation (#771).

mlr3 0.13.2

CRAN release: 2022-02-14

  • Setting a fallback learner for a learner with encapsulation in its default settings now automatically sets encapsulation to "evaluate" (#763).
  • as_task_classif() and as_task_regr() now support the construction of tasks using the formula interface, e.g. as_task_regr(mpg ~ ., data = mtcars) (#761).
  • Added default_values() function to extract parameter default values from Learner objects.
  • The row role "validation" has been renamed to "holdout". In the next release, mlr3 will start switching to the now more common terms "train"/"validation" instead of "train"/"test" for the sets created during resampling.

mlr3 0.13.1

CRAN release: 2022-01-19

  • Improved performance for many operations on ResampleResult and BenchmarkResult.
  • resample() and benchmark() got a new argument clone to control which objects to clone before performing computations.
  • Tasks are checked for infinite values during the conversion from data.frame to Task in as_task_classif() and as_task_regr(). A warning is signaled if any column contains infinite values.

mlr3 0.13.0

CRAN release: 2021-11-16

  • Learners which are capable of resuming/continuing (e.g., learner (classif|regr|surv).xgboost with hyperparameter nrounds updated) can now optionally store a stack of trained learners to be used to hotstart their training. Note that this feature is still somewhat experimental. See HotstartStack and #719.
  • New measures to score similarity of selected feature sets: sim.jaccard (Jaccard Index) and sim.phi (Phi coefficient) (#690).
  • predict_newdata() now also supports DataBackend as input.
  • New function install_pkgs() to install required packages. This generic works for all objects with a packages field as well as ResampleResult and BenchmarkResult (#728).
  • New learner regr.debug for debugging.
  • New Task method $set_levels() to control how data with factor columns is returned, independent of the used DataBackend.
  • Measures now return NA if prerequisite are not met (#699). This allows to conveniently score your experiments with multiple measures having different requirements.
  • Feature names may no longer contain the special character %.

mlr3 0.12.0

CRAN release: 2021-08-05

  • New method to assign labels to columns in tasks: Task$label(). These will be used in visualizations in the future.
  • New method to add stratification variables: Task$add_strata().
  • New helper function partition() to split a task into a training and test set.
  • New standardized getter loglik() for class Learner.
  • New measures "aic" and "bic" to compute the Akaike Information Criterion or the Bayesian Information Criterion, respectively.
  • New Resampling method: ResamplingCustomCV. Creates a custom resampling split based on the levels of a user-provided factor variable.
  • New argument encapsulate for resample() and benchmark() to conveniently enable encapsulation and also set the fallback learner to the featureless learner. This is simply for convenience, configuring each learner individually is still possible and allows a more fine-grained control (#634, #642).
  • New field parallel_predict for Learner to enable parallel predictions via the future backend. This currently is only enabled while calling the $predict() or $predict_newdata methods and is disabled during resample() and benchmark() where you have other means to parallelize.
  • Deprecated public (and already documented as internal) field $data in ResampleResult and BenchmarkResult to simplify the API and avoid confusion. The converter as.data.table() can be used instead to access the internal data.
  • Measures now have formal hyperparameters. A popular example where this is required is the F1 score, now implemented with customizable beta.
  • Changed default of argument ordered in Task$data() from TRUE to FALSE.
  • Fixed getter ResamplingRepeatedCV$folds() (#643).
  • Fixed hashing of some measures.
  • Removed experimental column role uri. This role be split up into multiple roles by the mlr3keras package.
  • Update paramtest to error on extra parameters

mlr3 0.11.0

CRAN release: 2021-03-05

  • Added a as.data.table.Resampling method.
  • Renamed column "row_id" to "row_ids" in the as.data.table() methods for PredictionClassif and PredictionRegr (#547).
  • Added converters as_prediction_classif() and as_prediction_regr() to reverse the operation of as.data.table.PredictionClassif() and as.data.table.PredictionRegr().
  • Specifying a weight column during learner$predict_newdata() is not mandatory anymore (#563).
  • Task$data() defaults to return only active rows and columns, instead of asserting to only return rows and columns. As a result, the $data() method can now also be used to query inactive rows and cols from the DataBackend.
  • New (experimental) column role uri which is intended to point to external resources, e.g. images on the file system.
  • New helper set_threads() to control the number of threads during calls to external packages. All objects will be migrated to have threading disabled in their defaults to avoid conflicting parallelization techniques (#605).
  • New option mlr3.debug: avoid calls to future in resample() and benchmark() to improve the readability of tracebacks.
  • New experimental option mlr3.allow_utf8_names: allow non-ascii characters in column names in tasks.

mlr3 0.10.0

CRAN release: 2021-01-21

  • Result containers ResampleResult and BenchmarkResult now optionally remove the DataBackend of the Tasks in order to reduce file size and memory footprint after serialization. To remove the backends from the containers, set store_backends to FALSE in resample() or benchmark(), respectively. Note that this behavior will eventually will be the default for future releases.
  • Prediction objects generated by Learner$predict_newdata() now have row ids starting from 1 instead auto incremented row ids of the training task.
  • as.data.table.DictionaryTasks now returns an additional column properties.
  • Added flag conditions to ResampleResult$score() and BenchmarkResult$score() to allow to work with failing learners more conveniently.

mlr3 0.9.0

CRAN release: 2020-12-06

  • New methods for Task: $set_col_roles and $set_row_roles as a replacement for the deprecated and less flexible $set_col_role and $set_row_role.
  • Learners can now have a timeout (#556).
  • Removed S3 method friedman.test.BenchmarkResult() in favor of the new mlr3benchmark package.

mlr3 0.8.0

CRAN release: 2020-10-21

  • MeasureOOBError now has set property minimize to TRUE.
  • New learner property "featureless" to tag learners which can operate on featureless tasks.
  • Fixed [ResampleResult] ignoring argument predict_sets for returned [Prediction] objects.
  • Compatibility with new version of lgr.

mlr3 0.7.0

CRAN release: 2020-10-07

  • Updated properties of featureless learners to apply it on all feature types (did not work on POSIXct columns).
  • Fixed measures being calculated as NaN for BenchmarkResult for resamplings with a single iteration (#551).
  • Fixed a bug where a broken heuristic disabled nested parallelization via package future (mlr3tuning#270).
  • ResampleResult and BenchmarkResult now share a common interface to store the experiment results. Manual construction is still possible with helper function as_result_data()
  • Fixed deep cloning of ResamplingCV and ResamplingRepeatedCV.
  • New measure classif.prauc (area under precision-recall curve).
  • Removed dependency on orphaned package bibtex.

mlr3 0.6.0

CRAN release: 2020-09-13

  • Compact in-memory representation of R6 objects to save space when saving objects via saveRDS() or serialize().
  • Objects in containers like ResampleResult or BenchmarkResult are now de-duplicated for an optimized serialization.
  • Fixed data set breast_cancer: all factor features are now correctly stored as ordered factors.
  • Added a new utility function convert_task().

mlr3 0.5.0

CRAN release: 2020-08-07

  • Added classification task breast_cancer
  • Added ResamplingLOO for leave-one-out resampling.
  • Regression now supports predict type "distr" using the distr6 package.
  • Fixed ResamplingBootstrap in combination with grouping (#514).
  • Fixed plot method of TaskGeneratorMoons.
  • Added hyperparameter keep_model to learners "classif.rpart" and "regr.rpart".

mlr3 0.4.0

CRAN release: 2020-07-22

  • Added new task generators ("cassini", "circle", "simplex", "spirals", and "moons").
  • Columns in tasks generated by task generators have been renamed to be more consistent.
  • Added a plot() method for most task generators.
  • Corrected data in task german_credit (#514).

mlr3 0.3.0

CRAN release: 2020-06-02

  • Package future.apply is now imported (instead of suggested). This is necessary to ensure reproducibility: This way exactly the same result is calculated, independent of the parallel backend.
  • Fixed a bug where prediction on new data for a task with blocking information raised an exception (#496).
  • New binding: Task$order.

mlr3 0.2.0

CRAN release: 2020-04-17

  • Some handy cheat sheets can now be downloaded from the project homepage.
  • Added new measures classif.bbrier (binary Brier score) and classif.mbrier (multi-class Brier score).
  • Added new Resampling: ResamplingInsample.
  • Added base class for unsupervised tasks: TaskUnsupervised.

mlr3 0.1.8

CRAN release: 2020-03-09

  • Added S3 methods to combine ResampleResults and BenchmarkResults with c().
  • Fixed a bug where automatic generation of row ids could lead to duplicated ids via Task$predict_newdata()/Task$rbind() (#423).

mlr3 0.1.7

CRAN release: 2020-02-23

  • Switched to new roxygen2 documentation format for R6 classes.

  • resample() and benchmark() now support progress bars via the package progressr.

  • Row ids now must be numeric. It was previously allowed to have character row ids, but this lead to confusion and unnecessary code bloat. Row identifiers (e.g., to be used in plots) can still be part of the task, with row role "name".

  • Row names can now be queried with Task$row_names.

  • DataBackendMatrix now supports to store an optional (numeric) dense part.

  • Added new method $filter() to filter ResampleResults to a subset of iterations.

  • Removed deprecated character() -> object converters.

  • Empty test sets are now handled separately by learners (#421). An empty prediction object is returned for all learners.

  • The internal train and predict function of Learner now should be implemented as private method: instead of public methods train_internal and predict_internal, private methods .train and .predict are now encouraged.

  • It is now encouraged to move some internal methods from public to private:

    • Learner$train_internal should now be private method $.train.
    • Learner$predict_internal should now be private method $.predict.
    • Measure$score_internal should now be private method $.score. The public methods will be deprecated in a future release.

  • Removed arguments from the constructor of measures classif.debug and classif.costs. These can be set directly by msr().

mlr3 0.1.6

CRAN release: 2019-12-19

  • We have published an article about mlr3 in the Journal of Open Source Software: https://joss.theoj.org/papers/10.21105/joss.01903. See citation("mlr3") for the citation info.

  • New method Learner$reset().

  • New method BenchmarkResult$filter().

  • Learners returned by BenchmarkResult$learners are reset to encourage the safer alternative BenchmarkResult$score() to access trained models.

  • Fix ordering of levels in PredictionClassif$set_threshold() (triggered an assertion).

mlr3 0.1.5

CRAN release: 2019-12-10

  • Switched from package Metrics to package mlr3measures.

  • Measures can now calculate all scores using micro or macro averaging (#400).

  • Measures can now be configured to return a customizable performance score (instead of NA) in case the score cannot be calculated.

  • Character columns are now treated differently from factor columns. In the long term, character() columns are supposed to store text.

  • Fixed a bug triggered by integer grouping variables in Task (#396).

  • benchmark_grid() now accepts instantiated resamplings under certain conditions.

mlr3 0.1.4

CRAN release: 2019-10-28

  • Task$set_col_roles() and Task$set_row_roles() are now deprecated. Instead it is recommended for now to work with the lists Task$col_roles and Task$row_roles directly.

  • Learner$predict_newdata() now works without argument task if the learner has been fitted with Learner$train() (#375).

  • Names of column roles have been unified ("weights", "label", "stratify" and "groups" have been renamed).

  • Replaced MeasureClassifF1 with MeasureClassifFScore and fixed a bug in the F1 performance calculation (#353). Thanks to @001ben for reporting.

  • Stratification is now controlled via a task column role (was a parameter of class Resampling before).

  • Added a S3 predict() method for class Learner to increase interoperability with other packages.

  • Many objects now come with a $help() which opens the respective manual page.

mlr3 0.1.3

CRAN release: 2019-09-18

  • It is now possible to predict and score results on the training set or on both training and test set. Learners can be instructed to predict on multiple sets by setting predict_sets (default: "test"). Measures operate on all sets specified in their field predict_sets (default: "test").

  • ResampleResult$prediction and ResampleResult$predictions() are now methods instead of fields, and allow to extract predictions for different predict sets.

  • ResampleResult$performance() has been renamed to ResampleResult$score() for consistency.

  • BenchmarkResult$performance() has been renamed to BenchmarkResult$score() for consistency.

  • Changed API for (internal) constructors accepting paradox::ParamSet(). Instead of passing the initial values separately, the initial values must now be set directly in the ParamSet.

mlr3 0.1.2

CRAN release: 2019-08-25

  • Deprecated support of automatically creating objects from strings. Instead, mlr3 provides the following helper functions intended to ease the creation of objects stored in dictionaries: tsk(), tgen(), lrn(), rsmp(), msr().

  • BenchmarkResult now ensures that the stored ResampleResults are in a persistent order. Thus, ResampleResults can now be addressed by their position instead of their hash.

  • New field BenchmarkResult$n_resample_results.

  • New field BenchmarkResult$hashes.

  • New method Task$rename().

  • New S3 generic as_benchmark_result().

  • Renamed Generator to TaskGenerator.

  • Removed the control object mlr_control().

  • Removed ResampleResult$combine().

  • Removed BenchmarkResult$best().

mlr3 0.1.1

CRAN release: 2019-07-25

  • Initial upload to CRAN.