Merge pull request #1323 from tidymodels/outcome-predictor-helpers

add recipes_name_predictors() and recipes_outcomes()

NAMESPACE

@@ -599,6 +599,8 @@ export(rand_id)
 export(recipe)
 export(recipes_eval_select)
 export(recipes_extension_check)
+export(recipes_names_outcomes)
+export(recipes_names_predictors)
 export(recipes_pkg_check)
 export(recipes_remove_cols)
 export(remove_original_cols)

NEWS.md

@@ -24,6 +24,8 @@
 
 * Improved error message for misspelled argument in step functions. (#1318)
 
+* Developer helper functions `recipes_names_predictors()` and `recipes_names_outcomes()` have been added to aid variable selection in steps. (#1026)
+
 # recipes 1.0.10
 
 ## Bug Fixes

R/developer.R

@@ -116,6 +116,10 @@
 #' [recipes_remove_cols()] should be used in `prep.step_*()` functions, and is
 #' used to remove columns from the data set, either by using the
 #' `object$removals` field or by using the `col_names` argument.
+#' 
+#' [recipes_names_predictors()] and [recipes_names_outcomes()] should be used in
+#' `prep.step_*()` functions, and are used to get names of predictors and
+#' outcomes. 
 #'
 #' [get_case_weights()] and [are_weights_used()] are functions that help you
 #' extract case weights and help determine if they are used or not within the

R/misc.R

@@ -955,3 +955,36 @@ recipes_remove_cols <- function(new_data, object, col_names = character()) {
   }
   new_data
 }
+
+#' Role indicators
+#'
+#' This helper function is meant to be used in `prep()` methods to identify
+#' predictors and outcomes by names.
+#'
+#' @param info data.frame with variable information of columns. 
+#'
+#' @return Character vector of column names.
+#' @keywords internal
+#'
+#' @seealso [developer_functions]
+#'
+#' @name recipes-role-indicator
+NULL
+
+#' @rdname recipes-role-indicator
+#' @export
+recipes_names_predictors <- function(info) {
+  get_from_info(info, "predictor")
+}
+
+#' @rdname recipes-role-indicator
+#' @export
+recipes_names_outcomes <- function(info) {
+  get_from_info(info, "outcome")
+}
+
+get_from_info <- function(info, role) {
+  res <- info$variable[info$role == role & !is.na(info$role)]
+
+  res
+}

_pkgdown.yml

@@ -165,6 +165,7 @@ reference:
     - prepper
     - recipes_eval_select
     - recipes_extension_check
+    - recipes-role-indicator
     - update.step
   - title: Tidy Methods
     contents: