better engine and mode checking code

NEWS.md

@@ -1,14 +1,21 @@
 # parsnip (development version)
 
+## Model Specification Changes
+
+* A model function (`gen_additive_mod()`) was added for generalized additive models. 
+
 * Each model now has a default engine that is used when the model is defined. The default for each model is listed in the help documents. This also adds functionality to declare an engine in the model specification function. `set_engine()` is still required if engine-specific arguments need to be added. (#513)
 
+* parsnip now checks for a valid combination of engine and mode (#529)
+
 * The default engine for `multinom_reg()` was changed to `nnet`. 
 
+## Other Changes
+
 * The helper functions `.convert_form_to_xy_fit()`, `.convert_form_to_xy_new()`, `.convert_xy_to_form_fit()`, and  `.convert_xy_to_form_new()` for converting between formula and matrix interface are now exported for developer use (#508).
 
 * Fix bug in `augment()` when non-predictor, non-outcome variables are included in data (#510).
 
-* A model function (`gen_additive_mod()`) was added for generalized additive models. 
 
 # parsnip 0.1.6
 

R/aaa_models.R

@@ -1,5 +1,7 @@
 # Initialize model environments
 
+all_modes <- c("classification", "regression", "censored regression")
+
 # ------------------------------------------------------------------------------
 
 ## Rules about model-related information
@@ -23,10 +25,9 @@
 
 # ------------------------------------------------------------------------------
 
-
 parsnip <- rlang::new_environment()
 parsnip$models <- NULL
-parsnip$modes <- c("regression", "classification", "unknown")
+parsnip$modes <- c(all_modes, "unknown")
 
 # ------------------------------------------------------------------------------
 
@@ -134,25 +135,119 @@ check_mode_val <- function(mode) {
 }
 
 
-stop_incompatible_mode <- function(spec_modes) {
+stop_incompatible_mode <- function(spec_modes, eng = NULL, cls = NULL) {
+  if (is.null(eng) & is.null(cls)) {
+    msg <- "Available modes are: "
+  }
+  if (!is.null(eng) & is.null(cls)) {
+    msg <- glue::glue("Available modes for engine {eng} are: ")
+  }
+  if (is.null(eng) & !is.null(cls)) {
+    msg <- glue::glue("Available modes for model type {cls} are: ")
+  }
+  if (!is.null(eng) & !is.null(cls)) {
+    msg <- glue::glue("Available modes for model type {cls} with engine {eng} are: ")
+  }
+
   msg <- glue::glue(
-    "Available modes are: ",
+    msg,
     glue::glue_collapse(glue::glue("'{spec_modes}'"), sep = ", ")
   )
   rlang::abort(msg)
 }
 
-# check if class and mode are compatible
-check_spec_mode_val <- function(cls, mode) {
-  spec_modes <- rlang::env_get(get_model_env(), paste0(cls, "_modes"))
+stop_incompatible_engine <- function(spec_engs, mode) {
+  msg <- glue::glue(
+    "Available engines for mode {mode} are: ",
+    glue::glue_collapse(glue::glue("'{spec_engs}'"), sep = ", ")
+  )
+  rlang::abort(msg)
+}
+
+stop_missing_engine <- function(cls) {
+  info <-
+    get_from_env(cls) %>%
+    dplyr::group_by(mode) %>%
+    dplyr::summarize(msg = paste0(unique(mode), " {",
+                                  paste0(unique(engine), collapse = ", "),
+                                  "}"),
+                     .groups = "drop")
+  if (nrow(info) == 0) {
+    rlang::abort(paste0("No known engines for `", cls, "()`."))
+  }
+  msg <- paste0(info$msg, collapse = ", ")
+  msg <- paste("Missing engine. Possible mode/engine combinations are:", msg)
+  rlang::abort(msg)
+}
+
+
+# check if class and mode and engine are compatible
+check_spec_mode_engine_val <- function(cls, eng, mode) {
+  all_modes <- c("unknown", all_modes)
+  if (!(mode %in% all_modes)) {
+    rlang::abort(paste0("'", mode, "' is not a known mode."))
+  }
+
+  model_info <- rlang::env_get(get_model_env(), cls)
+
+  # Cases where the model definition is in parsnip but all of the engines
+  # are contained in a different package
+  if (nrow(model_info) == 0) {
+    check_mode_with_no_engine(cls, mode)
+    return(invisible(NULL))
+  }
+
+  # ------------------------------------------------------------------------------
+  # First check engine against any mode for the given model class
+
+  spec_engs <- model_info$engine
+  # engine is allowed to be NULL
+  if (!is.null(eng) && !(eng %in% spec_engs)) {
+    rlang::abort(
+      paste0(
+        "Engine '", eng, "' is not supported for `", cls, "()`. See ",
+        "`show_engines('", cls, "')`."
+      )
+    )
+  }
+
+  # ----------------------------------------------------------------------------
+  # Check modes based on model and engine
+
+  spec_modes <- model_info$mode
+  if (!is.null(eng)) {
+    spec_modes <- spec_modes[model_info$engine == eng]
+  }
+  spec_modes <- unique(c("unknown", spec_modes))
+
   if (is.null(mode) || length(mode) > 1) {
-    stop_incompatible_mode(spec_modes)
+    stop_incompatible_mode(spec_modes, eng)
   } else if (!(mode %in% spec_modes)) {
-    stop_incompatible_mode(spec_modes)
+    stop_incompatible_mode(spec_modes, eng)
   }
+
+  # ----------------------------------------------------------------------------
+  # Check engine based on model and model
+
+  # How check for compatibility with the chosen mode (if any)
+  if (!is.null(mode) && mode != "unknown") {
+    spec_engs <- spec_engs[model_info$mode == mode]
+  }
+  spec_engs <- unique(spec_engs)
+  if (!is.null(eng) && !(eng %in% spec_engs)) {
+    stop_incompatible_engine(spec_engs, mode)
+  }
+
   invisible(NULL)
 }
 
+check_mode_with_no_engine <- function(cls, mode) {
+  spec_modes <- get_from_env(paste0(cls, "_modes"))
+  if (!(mode %in% spec_modes)) {
+    stop_incompatible_mode(spec_modes, cls = cls)
+  }
+}
+
 check_engine_val <- function(eng) {
   if (rlang::is_missing(eng) || length(eng) != 1 || !is.character(eng))
     rlang::abort("Please supply a character string for an engine (e.g. `'lm'`).")
@@ -625,8 +720,7 @@ get_dependency <- function(model) {
 set_fit <- function(model, mode, eng, value) {
   check_model_exists(model)
   check_eng_val(eng)
-  check_mode_val(mode)
-  check_engine_val(eng)
+  check_spec_mode_engine_val(model, eng, mode)
   check_fit_info(value)
 
   current <- get_model_env()
@@ -692,8 +786,7 @@ get_fit <- function(model) {
 set_pred <- function(model, mode, eng, type, value) {
   check_model_exists(model)
   check_eng_val(eng)
-  check_mode_val(mode)
-  check_engine_val(eng)
+  check_spec_mode_engine_val(model, eng, mode)
   check_pred_info(value, type)
 
   current <- get_model_env()

R/arguments.R

@@ -79,9 +79,9 @@ set_mode <- function(object, mode) {
   cls <- class(object)[1]
   if (rlang::is_missing(mode)) {
     spec_modes <- rlang::env_get(get_model_env(), paste0(cls, "_modes"))
-    stop_incompatible_mode(spec_modes)
+    stop_incompatible_mode(spec_modes, cls = cls)
   }
-  check_spec_mode_val(cls, mode)
+  check_spec_mode_engine_val(cls, object$engine, mode)
   object$mode <- mode
   object
 }

R/engines.R

@@ -10,25 +10,6 @@ possible_engines <- function(object, ...) {
   unique(engs$engine)
 }
 
-stop_incompatible_engine <- function(avail_eng) {
-  msg <- glue::glue(
-    "Available engines are: ",
-    glue::glue_collapse(glue::glue("'{avail_eng}'"), sep = ", ")
-  )
-  rlang::abort(msg)
-}
-
-check_engine <- function(object) {
-  avail_eng <- possible_engines(object)
-  eng <- object$engine
-  if (is.null(eng) || length(eng) > 1) {
-    stop_incompatible_engine(avail_eng)
-  } else if (!(eng %in% avail_eng)) {
-    stop_incompatible_engine(avail_eng)
-  }
-  object
-}
-
 # ------------------------------------------------------------------------------
 
 shhhh <- function(x)
@@ -90,16 +71,16 @@ load_libs <- function(x, quiet, attach = FALSE) {
 #' translate(mod, engine = "glmnet")
 #' @export
 set_engine <- function(object, engine, ...) {
+  mod_type <- class(object)[1]
   if (!inherits(object, "model_spec")) {
     rlang::abort("`object` should have class 'model_spec'.")
   }
 
   if (rlang::is_missing(engine)) {
-    avail_eng <- possible_engines(object)
-    stop_incompatible_engine(avail_eng)
+    stop_missing_engine(mod_type)
   }
   object$engine <- engine
-  object <- check_engine(object)
+  check_spec_mode_engine_val(mod_type, object$engine, object$mode)
 
   if (object$engine == "liquidSVM") {
     lifecycle::deprecate_soft(
@@ -109,7 +90,7 @@ set_engine <- function(object, engine, ...) {
   }
 
   new_model_spec(
-    cls = class(object)[1],
+    cls = mod_type,
     args = object$args,
     eng_args = enquos(...),
     mode = object$mode,

R/misc.R

@@ -23,9 +23,6 @@ check_empty_ellipse <- function (...)  {
   terms
 }
 
-all_modes <- c("classification", "regression", "censored regression")
-
-
 deparserizer <- function(x, limit = options()$width - 10) {
   x <- deparse(x, width.cutoff = limit)
   x <- gsub("^    ", "", x)
@@ -192,7 +189,7 @@ update_dot_check <- function(...) {
 #' @rdname add_on_exports
 new_model_spec <- function(cls, args, eng_args, mode, method, engine) {
 
-  check_spec_mode_val(cls, mode)
+  check_spec_mode_engine_val(cls, engine, mode)
 
   out <- list(args = args, eng_args = eng_args,
               mode = mode, method = method, engine = engine)

R/translate.R

@@ -59,14 +59,15 @@ translate.default <- function(x, engine = x$engine, ...) {
   mod_name <- specific_model(x)
 
   x$engine <- engine
-  x <- check_engine(x)
-
   if (x$mode == "unknown") {
     rlang::abort("Model code depends on the mode; please specify one.")
   }
 
-  if (is.null(x$method))
+  check_spec_mode_engine_val(class(x)[1], x$engine, x$mode)
+
+  if (is.null(x$method)) {
     x$method <- get_model_spec(mod_name, x$mode, engine)
+  }
 
   arg_key <- get_args(mod_name, engine)
 
@@ -174,7 +175,7 @@ deharmonize <- function(args, key) {
 
 add_methods <- function(x, engine) {
   x$engine <- engine
-  x <- check_engine(x)
+  check_spec_mode_engine_val(class(x)[1], x$engine, x$mode)
   x$method <- get_model_spec(specific_model(x), x$mode, x$engine)
   x
 }

man/rmd/boost_tree_C5.0.Rmd

@@ -13,7 +13,7 @@ defaults <-
 param <-
  boost_tree() %>% 
   set_engine("C5.0") %>% 
-  set_mode("regression") %>% 
+  set_mode("classification") %>% 
   tunable() %>% 
   dplyr::select(-source, -component, -component_id, parsnip = name) %>% 
   dplyr::mutate(

man/rmd/decision_tree_C5.0.Rmd

@@ -13,7 +13,7 @@ defaults <-
 param <-
  decision_tree() %>% 
   set_engine("C5.0") %>% 
-  set_mode("regression") %>% 
+  set_mode("classification") %>% 
   tunable() %>% 
   dplyr::select(-source, -component, -component_id, parsnip = name) %>% 
   dplyr::mutate(