added pipe-able functions for setting elements

Author: topepo

NAMESPACE

@@ -79,6 +79,8 @@ export(predict_predint.model_fit)
 export(predict_raw)
 export(predict_raw.model_fit)
 export(rand_forest)
+export(set_args)
+export(set_mode)
 export(show_call)
 export(surv_reg)
 export(translate)

R/arguments.R

@@ -64,3 +64,56 @@ check_others <- function(args, obj, core_args) {
   }
   args
 }
+
+#' Change elements of a model specification
+#'
+#' `set_args` can be used to modify the arguments of a model specification while
+#'  `set_mode` is used to change the model's mode.
+#'
+#' @param object A model specification.
+#' @param ... One or more named model arguments.
+#' @param mode A character string for the model type (e.g. "classification" or
+#'  "regression")
+#' @return An updated model object.
+#' @details `set_args` will replace existing values of the arguments.
+#'
+#' @examples
+#' rand_forest()
+#'
+#' rand_forest() %>%
+#'   set_args(mtry = 3, importance = TRUE) %>%
+#'   set_mode("regression")
+#'
+#' @export
+set_args <- function(object, ...) {
+  the_dots <- list(...)
+  if (length(the_dots) == 0)
+    stop("Please pass at least one named argument.", call. = FALSE)
+  main_args <- names(object$args)
+  new_args <- names(the_dots)
+  for (i in new_args) {
+    if (any(main_args == i)) {
+      object$args[[i]] <- the_dots[[i]]
+    } else {
+      object$others[[i]] <- the_dots[[i]]
+    }
+  }
+  object
+}
+
+#' @rdname set_args
+#' @export
+set_mode <- function(object, mode) {
+  if (is.null(mode))
+    return(object)
+  mode <- mode[1]
+  if (!(any(all_modes == mode))) {
+    stop("`mode` should be one of ",
+         paste0("'", all_modes, "'", collapse = ", "),
+         call. = FALSE)
+  }
+  object$mode <- mode
+  object
+}
+
+

man/set_args.Rd

@@ -0,0 +1,32 @@
+library(testthat)
+library(parsnip)
+library(dplyr)
+
+context("changing arguments and engine")
+
+test_that('pipe arguments', {
+  mod_1 <- rand_forest() %>%
+    set_args(mtry = 1, something = "blah")
+  expect_equal(mod_1$args$mtry, 1)
+  expect_equal(mod_1$others$something, "blah")
+  
+  mod_2 <- rand_forest(mtry = 2, others = list(var = "x")) %>%
+    set_args(mtry = 1, something = "blah")
+  expect_equal(mod_2$args$mtry, 1)
+  expect_equal(mod_2$others$something, "blah")
+  expect_equal(mod_2$others$var, "x") 
+  
+  expect_error(rand_forest() %>% set_args())
+  
+})
+
+
+test_that('pipe engine', {
+  mod_1 <- rand_forest() %>%
+    set_mode("regression")
+  expect_equal(mod_1$mode, "regression")
+  
+  expect_error(rand_forest() %>% set_mode())
+  expect_error(rand_forest() %>% set_mode(2))
+  expect_error(rand_forest() %>% set_mode("haberdashery"))
+})