(try to) determine the default values for parsnip model arguments

get_default_values.R

get_default_values <- function(model, engine, mode) {
  eng <- engine
  mod_args <- 
    parsnip::get_from_env(paste0(model, "_args")) %>% 
    dplyr::filter(engine == eng)
  model_fun <- 
    parsnip::get_from_env(paste0(model, "_fit")) %>% 
    dplyr::filter(engine == eng) %>% 
    dplyr::mutate(pkg = purrr::map_chr(value, ~ .x$func["pkg"]),
           fun = purrr::map_chr(value, ~ .x$func["fun"]))
  if (nrow(model_fun) > 1) {
    if (rlang::is_missing(mode)) {
      rlang::abort("Please select a mode.")
    }
    md <- mode
    model_fun <- 
      model_fun %>% 
      dplyr::filter(mode == md)
  }
  model_func <- utils::getFromNamespace(model_fun$fun, ns = model_fun$pkg)
  model_info <- formals(model_func)
  model_info <- model_info[mod_args$original]
  model_info <- purrr::map(model_info, ~ if(is.null(.x)) "<cannot determine>" else .x)
  model_defaults <- format(model_info)
  mod_args$default <- model_defaults
  mod_args %>% dplyr::select(engine, parsnip, original, default)
}
get_default_values("boost_tree", "C5.0")
get_default_values("boost_tree", "spark", "regression")
get_default_values("decision_tree", "rpart", "regression")
get_default_values("mlp", "keras", "regression")