Themis package functions

[mb706]

what other methods exist in the themis package that we could use?

[advieser]

themis implements differrent methods for handling unbalanced data. This is a summary based on the manual:

• adasyn (Adaptive Synthetic Algorithm) which generates synthetic positive instances; works for tasks with only numeric features that have no NAs.
• bsmote (Borderline SMOTE) which generates new examples of the minority class using nearest neighbors of these cases in the border region between classes; works for tasks with only numeric features that have no NAs.
• nearmiss which eliminates entries from the majority class that have the smallest distance to the minority class; works for tasks with only numeric features that have no NAs.
• smote, see PipeOpSmote
• smotenc, currently under development as PipeOpSmoteNC
• tomek which removes observations that are part of tomek links; works for tasks with only numeric features that have no NAs.

Furthermore, the package implements a recipe for one external function:

• ROSE::ROSE() which creates a sample of synthetic data by enlarging the features space of minority and majority class examples; for inbalanced data in binary classification tasks.

Lastly, the package implements a recipe (step_upsampling) without a separate implementation, which will replicate rows of a data set to make the occurrence of levels in a specific factor level equal. Only intended for training. Implemented as PipeOpClassBalancing.

Of course, implementing these in mlr3pipelines wouldn't be necessary if pipelines was generally interoperable with tidymodels (https://github.com/mlr-org/mlr3pipelines/issues/490). https://github.com/mlr-org/mlr3pipelines/issues/490 refers to interoperabilitiy in the sense that a pipeline could be used as a step in a tidymodels recipe.

[advieser]

Of these, the following are also implemented in smotefamily:

• adasyn
• blsmote (Borderline-Smote)

and additionally:

• ANS (Adaptive Neighbor SMOTE)
• DBSMOTE (Density-based SMOTE)
• RSLS (Relocating Safe-Level SMOTE)
• SLS (Safe-level SMOTE)

[mb706]

We have the themis content itself already, so I will close this for now.