5.1 The Building Blocks: PipeOps

The building blocks of mlr3pipelines are PipeOp-objects (PO). They can be constructed directly using PipeOp<NAME>$new(), but the recommended way is to retrieve them from the mlr_pipeops dictionary.

Single POs can be created using mlr_pipeops$get(<name>).

Some POs require additional arguments for construction.

Hyperparameters of POs can be set through the param_vals argument. Here we set the fraction of features for a filter.

The figure below shows an exemplary PipeOp: It takes an input, transforms it during .$train and .$predict and returns data.

A PipeOperator

A PipeOperator