understanding tune(), update_model(), and parameters()

Machine Learning and Modeling
2

Hi there,

I'm getting the same error when I try to tune both the recipe and the model. Perhaps a github issue with full reprex? Here is mine (sorry for not rendering, I'm getting an error trying to run the reprex locally :sob:)

library(modeldata)
data("stackoverflow")
library(tidyverse)
library(tidymodels)
set.seed(100) # Important!

# make smaller to save time
so_split <- initial_split(sample_n(stackoverflow, size = 300), strata = Remote)
so_train <- training(so_split)
so_test  <- testing(so_split)
# again, simpler so runs faster
so_folds <- vfold_cv(so_train, v = 2, strata = Remote)

so_rec <- recipe(Remote ~ ., 
                   data = so_train) %>% 
  step_dummy(all_nominal(), -all_outcomes()) %>% 
  step_lincomb(all_predictors()) %>% 
  step_downsample(Remote)

tune_rec <- recipe(Remote ~ ., 
                 data = so_train) %>% 
  step_dummy(all_nominal(), -all_outcomes()) %>% 
  step_lincomb(all_predictors()) %>% 
  step_downsample(Remote, under_ratio = tune())

# no tuning
rf_spec <- 
  rand_forest() %>% 
  set_engine("ranger") %>% 
  set_mode("classification")

# add tuning
tune_spec <-
  rand_forest(mtry = tune(),
              min_n = tune()) %>% 
  set_engine("ranger") %>% 
  set_mode("classification")

# define 3 workflows
tuneboth_wf <-
  workflow() %>% 
  add_recipe(tune_rec) %>% 
  add_model(tune_spec)

tunerec_wf <-
  workflow() %>% 
  add_recipe(tune_rec) %>% 
  add_model(rf_spec)

tunemod_wf <-
  workflow() %>% 
  add_recipe(so_rec) %>% 
  add_model(tune_spec)

# this won't work
tuneboth_wf %>% 
  tune_grid(resamples = so_folds)

# works
tunerec_wf %>% 
  tune_grid(resamples = so_folds)

# works
tunemod_wf %>% 
  tune_grid(resamples = so_folds)
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