Learn R Programming

mlr (version 2.3)

makeMulticlassWrapper: Fuse learner with multiclass method.

Description

Fuses a base learner with a multi-class method. Creates a learner object, which can be used like any other learner object. This way learners which can only handle binary classification will be able to handle multi-class problems, too.

We use a multiclass-to-binary reduction principle, where multiple binary problems are created from the multiclass task. How these binary problems are generated is defined by an error-correcting-output-code (ECOC) code book. This also allows the simple and well-known one-vs-one and one-vs-rest approaches. Decoding is currently done via Hamming decoding, see e.g. here http://jmlr.org/papers/volume11/escalera10a/escalera10a.pdf.

Currently, the approach always operates on the discrete predicted labels of the binary base models (instead of their probabilities) and the created wrapper cannot predict posterior probabilities.

Usage

makeMulticlassWrapper(learner, mcw.method = "onevsrest")

Arguments

Value

[Learner].

See Also

Other wrapper: CostSensClassifModel, CostSensClassifWrapper, makeCostSensClassifWrapper; CostSensRegrModel, CostSensRegrWrapper, makeCostSensRegrWrapper; makeBaggingWrapper; makeDownsampleWrapper; makeFeatSelWrapper; makeFilterWrapper; makeImputeWrapper; makeOverBaggingWrapper; makeOversampleWrapper, makeUndersampleWrapper; makePreprocWrapperCaret; makePreprocWrapper; makeSMOTEWrapper; makeTuneWrapper; makeWeightedClassesWrapper