added support for boosting aliases in R package and test on skipping …

…early boosting

R-package/R/aliases.R

@@ -0,0 +1,15 @@
+# Central location for paramter aliases.
+# See https://lightgbm.readthedocs.io/en/latest/Parameters.html#core-parameters
+
+# [description] List of respected parameter aliases. Wrapped in a function to take advantage of
+#               lazy evaluation (so it doesn't matter what order R sources files during installation).
+# [return] A named list, where each key is a main LightGBM parameter and  each value is a character
+#          vector of corresponding aliases.
+.PARAMETER_ALIASES <- function(){
+    return(list(
+        "boosting" = c(
+            "boosting_type"
+            , "boost"
+        )
+    ))
+}

R-package/R/callback.R

@@ -37,7 +37,12 @@ cb.reset.parameters <- function(new_params) {
 
     # Some parameters are not allowed to be changed,
     # since changing them would simply wreck some chaos
-    not_allowed <- c("num_class", "metric", "boosting_type")
+    not_allowed <- c(
+      "num_class"
+      , "metric"
+      , "boosting"
+      , .PARAMETER_ALIASES()[["boosting"]]
+    )
     if (any(pnames %in% not_allowed)) {
       stop("Parameters ", paste0(pnames[pnames %in% not_allowed], collapse = ", "), " cannot be changed during boosting")
     }

R-package/R/lgb.cv.R

@@ -224,8 +224,18 @@ lgb.cv <- function(params = list(),
   # Did user pass parameters that indicate they want to use early stopping?
   using_early_stopping_via_args <- !is.null(early_stopping_rounds)
 
+  boosting_param_names <- c("boosting", .PARAMETER_ALIASES()[["boosting"]])
+  using_dart <- any(
+    sapply(
+      X = boosting_param_names
+      , FUN = function(param){
+        identical(params[[param]], 'dart')
+      }
+    )
+  )
+
   # Cannot use early stopping with 'dart' boosting
-  if (identical(params$boosting, "dart")){
+  if (using_dart){
     warning("Early stopping is not available in 'dart' mode.")
     using_early_stopping_via_args <- FALSE
 

R-package/R/lgb.train.R

@@ -207,8 +207,18 @@ lgb.train <- function(params = list(),
   # Did user pass parameters that indicate they want to use early stopping?
   using_early_stopping_via_args <- !is.null(early_stopping_rounds)
 
+  boosting_param_names <- c("boosting", .PARAMETER_ALIASES()[["boosting"]])
+  using_dart <- any(
+    sapply(
+      X = boosting_param_names
+      , FUN = function(param){
+        identical(params[[param]], 'dart')
+      }
+    )
+  )
+
   # Cannot use early stopping with 'dart' boosting
-  if (identical(params$boosting, "dart")){
+  if (using_dart){
     warning("Early stopping is not available in 'dart' mode.")
     using_early_stopping_via_args <- FALSE
 

R-package/tests/testthat/test_parameters.R

@@ -40,3 +40,30 @@ test_that("Feature penalties work properly", {
   # Ensure that feature is not used when feature_penalty = 0
   expect_length(var_gain[[length(var_gain)]], 0)
 })
+
+expect_true(".PARAMETER_ALIASES() returns a named list", {
+  param_aliases <- .PARAMETER_ALIASES()
+  expect_true(is.list(param_aliases))
+  expect_true(is.character(names(param_aliases)))
+})
+
+expect_true("training should warn if you use 'dart' boosting, specified with 'boosting' or aliases", {
+  for (boosting_param in c("boosting", .PARAMETER_ALIASES()[["boosting"]])){
+    expect_warning({
+      result <- lightgbm(
+        data = train$data
+        , label = train$label
+        , num_leaves = 5
+        , learning_rate = 0.05
+        , nrounds = 5
+        , objective = "binary"
+        , metric = "binary_error"
+        , verbose = -1
+        , params = stats::setNames(
+          object = "dart"
+          , nm = boosting_param
+        )
+      )
+    }, regexp = "Early stopping is not available in 'dart' mode")
+  }
+})