more engine docs

Author: topepo

NAMESPACE

@@ -168,6 +168,7 @@ export(set_model_mode)
 export(set_new_model)
 export(set_pred)
 export(show_call)
+export(show_engines)
 export(show_fit)
 export(show_model_info)
 export(surv_reg)

NEWS.md

@@ -1,5 +1,7 @@
 # parsnip (development version)
 
+* `show_engines()` will provide information on the current set for a model. 
+
 # parsnip 0.1.3
 
  * A `glance()` method for `model_fit` objects was added (#325)

R/boost_tree.R

@@ -62,6 +62,8 @@
 #' \item \pkg{Spark}: `"spark"`
 #' }
 #'
+#' For this model, other packages may add additional engines. Use
+#' [show_engines()] to see the current set of engines.
 #'
 #' @includeRmd man/rmd/boost-tree.Rmd details
 #'

R/engines.R

@@ -106,3 +106,24 @@ set_engine <- function(object, engine, ...) {
     engine = object$engine
   )
 }
+
+#' Display available engines for a model
+#'
+#' The possible engines for a model may depend on what packages are loaded. There
+#' are some `parsnip`-adjacent packages that only add engines to existing models.
+#' @param x The name of a `parsnip` model (e.g., "linear_reg", "mars", etc.)
+#' @return A tibble.
+#' show_engines("linear_reg")
+#' @export
+show_engines <- function(x) {
+  if (!is.character(x) || length(x) > 1) {
+    rlang::abort("`show_engines()` takes a single character string as input.")
+  }
+  res <- try(get_from_env(x), silent = TRUE)
+  if (inherits(res, "try-error")) {
+    rlang::abort(
+      paste0("No results found for model function '", x, "'.")
+    )
+  }
+  res
+}

R/linear_reg.R

@@ -42,6 +42,9 @@
 #' \item \pkg{keras}: `"keras"`
 #' }
 #'
+#' For this model, other packages may add additional engines. Use
+#' [show_engines()] to see the current set of engines.
+#'
 #' @includeRmd man/rmd/linear-reg.Rmd details
 #'
 #' @note For models created using the spark engine, there are

R/logistic_reg.R

@@ -40,6 +40,9 @@
 #' \item \pkg{keras}: `"keras"`
 #' }
 #'
+#' For this model, other packages may add additional engines. Use
+#' [show_engines()] to see the current set of engines.
+#'
 #' @includeRmd man/rmd/logistic-reg.Rmd details
 #'
 #' @note For models created using the spark engine, there are