APIs for determining original predictor columns

NEWS.md

@@ -1,5 +1,8 @@
 # workflows (development version)
 
+* Added a standalone file `standalone-input-names.R` with APIs for returning the
+names of the predictors in the original data given to `fit()`. 
+
 * Each of the `pull_*()` functions soft-deprecated in workflows v0.2.3 now warn on every usage. 
 
 * `add_recipe()` will now error informatively when supplied a trained recipe (#179).

R/standalone-input-names.R

@@ -0,0 +1,83 @@
+# ---
+# repo: tidymodels/workflows
+# file: standalone-input-names.R
+# last-updated: 2024-01-291
+# license: https://unlicense.org
+# requires: cli, rlang
+# ---
+
+# This file provides a portable set of helper functions for determining the
+# names of the predictor columns used as inputs into a workflow.
+
+# ## Changelog
+# 2024-01-21
+# * First version
+# 2024-01-29
+# * Changes after PR review
+
+# nocov start
+
+# ------------------------------------------------------------------------------
+# Primary functions
+
+# @param x A _fitted_ workflow or recipe.
+# @param call An environment indicating where the top-level function was invoked
+# to print out better errors.
+# @return A character vector of sorted columns names.
+
+.get_input_predictors_workflow <- function(x, ..., call = rlang::current_env()) {
+  check_workflow_fit(x, call = call)
+  # We can get the columns that are inputs to the recipe but some of these may
+  # not be predictors. We'll interrogate the recipe and pull out the current
+  # predictor names from the original input
+  if ("recipe" %in% names(x$pre$actions)) {
+    mold <- x$pre$mold
+    rec <- mold$blueprint$recipe
+    res <- .get_input_predictors_recipe(rec)
+  } else {
+    res <- blueprint_ptype(x)
+  }
+  sort(unique(res))
+}
+
+.get_input_predictors_recipe <- function(x, ..., call = rlang::current_env()) {
+  check_recipe_fit(x, call = call)
+  var_info <- x$last_term_info
+
+  keep_rows <- var_info$source == "original" & is_predictor_role(var_info)
+  var_info <- var_info[keep_rows,]
+  var_info$variable
+}
+
+.get_input_outcome_workflow <- function(x) {
+  check_workflow_fit(x)
+  names(x$pre$mold$blueprint$ptypes$outcomes)
+}
+
+# ------------------------------------------------------------------------------
+# Helper functions
+
+check_workflow_fit <- function(x, call) {
+  if (!x$trained) {
+    cli::cli_abort("The workflow should be trained.", call = call)
+  }
+  invisible(NULL)
+}
+
+check_recipe_fit <- function(x, call) {
+  is_trained <- vapply(x$steps, function(x) x$trained, logical(1))
+  if (!all(is_trained)) {
+    cli::cli_abort("All recipe steps should be trained.", call = call)
+  }
+  invisible(NULL)
+}
+
+blueprint_ptype <- function(x) {
+  names(x$pre$mold$blueprint$ptypes$predictors)
+}
+
+is_predictor_role <- function(x) {
+  vapply(x$role, function(x) any(x == "predictor"), logical(1))
+}
+
+# nocov end

tests/testthat/_snaps/standalone-input-names.md

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+# get recipe input column names
+
+    Code
+      workflows:::.get_input_predictors_workflow(workflow)
+    Condition
+      Error in `workflows:::.get_input_predictors_workflow()`:
+      ! The workflow should be trained.
+
+---
+
+    Code
+      workflows:::.get_input_predictors_recipe(rec_with_id)
+    Condition
+      Error in `workflows:::.get_input_predictors_recipe()`:
+      ! All recipe steps should be trained.
+
+# get formula input column names
+
+    Code
+      workflows:::.get_input_predictors_workflow(workflow)
+    Condition
+      Error in `workflows:::.get_input_predictors_workflow()`:
+      ! The workflow should be trained.
+
+# get predictor input column names
+
+    Code
+      workflows:::.get_input_predictors_workflow(workflow)
+    Condition
+      Error in `workflows:::.get_input_predictors_workflow()`:
+      ! The workflow should be trained.
+

tests/testthat/test-standalone-input-names.R

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+test_that("get recipe input column names", {
+  skip_if_not_installed("modeldata")
+  skip_if_not_installed("recipes")
+
+  library(recipes)
+
+  data(cells, package = "modeldata")
+
+  cells <- cells[, 1:10]
+  pred_names <- sort(names(cells)[3:10])
+
+  rec_with_id <-
+    recipes::recipe(class ~ ., cells) %>%
+    update_role(case, new_role = "destination") %>%
+    step_rm(angle_ch_1) %>%
+    step_pca(all_predictors())
+
+  workflow <- workflow()
+  workflow <- add_recipe(workflow, rec_with_id)
+  workflow <- add_model(workflow, parsnip::logistic_reg())
+  workflow_fit <- fit(workflow, cells)
+
+  expect_snapshot(
+    workflows:::.get_input_predictors_workflow(workflow),
+    error = TRUE
+  )
+  expect_equal(
+    workflows:::.get_input_predictors_workflow(workflow_fit),
+    pred_names
+  )
+  expect_snapshot(
+    workflows:::.get_input_predictors_recipe(rec_with_id),
+    error = TRUE
+  )
+
+})
+
+test_that("get formula input column names", {
+  skip_if_not_installed("modeldata")
+
+  data(Chicago, package = "modeldata")
+
+  Chicago <- Chicago[, c("ridership", "date", "Austin")]
+  pred_names <- sort(c("date", "Austin"))
+
+  workflow <- workflow()
+  workflow <- add_formula(workflow, ridership ~ .)
+  workflow <- add_model(workflow, parsnip::linear_reg())
+  workflow_fit <- fit(workflow, Chicago)
+
+  expect_snapshot(
+    workflows:::.get_input_predictors_workflow(workflow),
+    error = TRUE
+  )
+  expect_equal(
+    workflows:::.get_input_predictors_workflow(workflow_fit),
+    pred_names
+  )
+
+})
+
+
+test_that("get predictor input column names", {
+  skip_if_not_installed("modeldata")
+
+  data(Chicago, package = "modeldata")
+
+  Chicago <- Chicago[, c("ridership", "date", "Austin")]
+  pred_names <- sort(c("date", "Austin"))
+
+  workflow <- workflow()
+  workflow <-
+    add_variables(workflow,
+                  outcomes = c(ridership),
+                  predictors = c(tidyselect::everything()))
+  workflow <- add_model(workflow, parsnip::linear_reg())
+  workflow_fit <- fit(workflow, Chicago)
+
+  expect_snapshot(
+    workflows:::.get_input_predictors_workflow(workflow),
+    error = TRUE
+  )
+  expect_equal(
+    workflows:::.get_input_predictors_workflow(workflow_fit),
+    pred_names
+  )
+
+})