A Pipeline of learners is a way to "chain" Learners together, where the
output of one learner is used as output for the next learner. This can be
used for things like screening, two stage machine learning methods, and Super
Learning. A pipeline is fit by fitting the first `Learner`

, calling
`chain()`

to create the next task, which becomes the training data for
the next `Learner`

. Similarly, for prediction, the predictions from the
first `Learner`

become the data to predict on for the next
`Learner`

.

`R6Class`

object.

Learner object with methods for training and prediction. See
`Lrnr_base`

for documentation on learners.

`...`

Parameters should be individual

`Learner`

s, in the order they should be applied.

Individual learners have their own sets of parameters. Below is a list of shared parameters, implemented by `Lrnr_base`

, and shared
by all learners.

`covariates`

A character vector of covariates. The learner will use this to subset the covariates for any specified task

`outcome_type`

A

`variable_type`

object used to control the outcome_type used by the learner. Overrides the task outcome_type if specified`...`

All other parameters should be handled by the invidual learner classes. See the documentation for the learner class you're instantiating

Other Learners:
`Custom_chain`

,
`Lrnr_HarmonicReg`

,
`Lrnr_arima`

,
`Lrnr_bartMachine`

,
`Lrnr_base`

,
`Lrnr_bilstm`

,
`Lrnr_bound`

,
`Lrnr_caret`

,
`Lrnr_cv_selector`

,
`Lrnr_cv`

,
`Lrnr_dbarts`

,
`Lrnr_define_interactions`

,
`Lrnr_density_discretize`

,
`Lrnr_density_hse`

,
`Lrnr_density_semiparametric`

,
`Lrnr_earth`

,
`Lrnr_expSmooth`

,
`Lrnr_gam`

,
`Lrnr_gbm`

,
`Lrnr_glm_fast`

,
`Lrnr_glmnet`

,
`Lrnr_glm`

,
`Lrnr_grf`

,
`Lrnr_gru_keras`

,
`Lrnr_gts`

,
`Lrnr_h2o_grid`

,
`Lrnr_hal9001`

,
`Lrnr_haldensify`

,
`Lrnr_hts`

,
`Lrnr_independent_binomial`

,
`Lrnr_lstm_keras`

,
`Lrnr_lstm`

,
`Lrnr_mean`

,
`Lrnr_multiple_ts`

,
`Lrnr_multivariate`

,
`Lrnr_nnet`

,
`Lrnr_nnls`

,
`Lrnr_optim`

,
`Lrnr_pca`

,
`Lrnr_pkg_SuperLearner`

,
`Lrnr_polspline`

,
`Lrnr_pooled_hazards`

,
`Lrnr_randomForest`

,
`Lrnr_ranger`

,
`Lrnr_revere_task`

,
`Lrnr_rpart`

,
`Lrnr_rugarch`

,
`Lrnr_screener_augment`

,
`Lrnr_screener_coefs`

,
`Lrnr_screener_correlation`

,
`Lrnr_screener_importance`

,
`Lrnr_sl`

,
`Lrnr_solnp_density`

,
`Lrnr_solnp`

,
`Lrnr_stratified`

,
`Lrnr_subset_covariates`

,
`Lrnr_svm`

,
`Lrnr_tsDyn`

,
`Lrnr_ts_weights`

,
`Lrnr_xgboost`

,
`Stack`

,
`define_h2o_X()`

,
`undocumented_learner`