From e62c2f7e842ee698a8f3dd1904c76384573afa8f Mon Sep 17 00:00:00 2001
From: topepo <mxkuhn@gmail.com>
Date: Sun, 16 Nov 2025 12:25:59 -0500
Subject: [PATCH 1/2] updated tunables for boosting

---
 NEWS.md     |  5 +++++
 R/tunable.R | 29 ++++++++++++++++++++++++++---
 2 files changed, 31 insertions(+), 3 deletions(-)

diff --git a/NEWS.md b/NEWS.md
index 7977fc733..e38bbf6b3 100644
--- a/NEWS.md
+++ b/NEWS.md
@@ -1,5 +1,10 @@
 # parsnip (development version)
 
+* Updates to some boosting tuning parameter information:
+  - lightgbm and catboost have smaller default ranges for the learning rate: -3 to -1 / 2 in log10 units.
+  - lightgbm, xgboost, catboost, and C5.0 have smaller default ranges for the sampling proportion: 0.5 to 1.0.
+  - catboost engine arguments were added for `max_leaves` and `l2_leaf_reg`. 
+
 * Enable generalized random forest (`grf`) models for classification, regression, and quantile regression modes. (#1288)
 
 * `surv_reg()` is now defunct and will error if called. Please use `survival_reg()` instead (#1206).
diff --git a/R/tunable.R b/R/tunable.R
index 8d2e86f8b..077121558 100644
--- a/R/tunable.R
+++ b/R/tunable.R
@@ -124,6 +124,21 @@ lightgbm_engine_args <-
     component_id = "engine"
   )
 
+catboost_engine_args <-
+  tibble::tibble(
+    name = c(
+      "max_leaves",
+      "l2_leaf_reg"
+    ),
+    call_info = list(
+      list(pkg = "dials", fun = "num_leaves"),
+      list(pkg = "dials", fun = "penalty", range = c(-4, 1))
+    ),
+    source = "model_spec",
+    component = "boost_tree",
+    component_id = "engine"
+  )
+
 ranger_engine_args <-
   tibble::tibble(
     name = c(
@@ -345,7 +360,7 @@ tunable.boost_tree <- function(x, ...) {
   if (x$engine == "xgboost") {
     res <- add_engine_parameters(res, xgboost_engine_args)
     res$call_info[res$name == "sample_size"] <-
-      list(list(pkg = "dials", fun = "sample_prop"))
+      list(list(pkg = "dials", fun = "sample_prop", range = c(0.5, 1.0)))
     res$call_info[res$name == "learn_rate"] <-
       list(list(pkg = "dials", fun = "learn_rate", range = c(-3, -1 / 2)))
   } else if (x$engine == "C5.0") {
@@ -353,11 +368,19 @@ tunable.boost_tree <- function(x, ...) {
     res$call_info[res$name == "trees"] <-
       list(list(pkg = "dials", fun = "trees", range = c(1, 100)))
     res$call_info[res$name == "sample_size"] <-
-      list(list(pkg = "dials", fun = "sample_prop"))
+      list(list(pkg = "dials", fun = "sample_prop", range = c(0.5, 1.0)))
   } else if (x$engine == "lightgbm") {
     res <- add_engine_parameters(res, lightgbm_engine_args)
     res$call_info[res$name == "sample_size"] <-
-      list(list(pkg = "dials", fun = "sample_prop"))
+      list(list(pkg = "dials", fun = "sample_prop", range = c(0.5, 1.0)))
+    res$call_info[res$name == "learn_rate"] <-
+      list(list(pkg = "dials", fun = "learn_rate", range = c(-3, -1 / 2)))
+  } else if (x$engine == "catboost") {
+    res <- add_engine_parameters(res, catboost_engine_args)
+    res$call_info[res$name == "learn_rate"] <-
+      list(list(pkg = "dials", fun = "learn_rate", range = c(-3, -1 / 2)))
+    res$call_info[res$name == "sample_size"] <-
+      list(list(pkg = "dials", fun = "sample_prop", range = c(0.5, 1.0)))
   }
   res
 }

From 8d9a8e7deeba491931fd9302c934e856672c5ed3 Mon Sep 17 00:00:00 2001
From: Emil Hvitfeldt <emil.hvitfeldt@posit.co>
Date: Wed, 19 Nov 2025 08:00:28 -0800
Subject: [PATCH 2/2] Update NEWS.md

---
 NEWS.md | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/NEWS.md b/NEWS.md
index e38bbf6b3..234821fc7 100644
--- a/NEWS.md
+++ b/NEWS.md
@@ -1,6 +1,6 @@
 # parsnip (development version)
 
-* Updates to some boosting tuning parameter information:
+* Updates to some boosting tuning parameter information: (#1306)
   - lightgbm and catboost have smaller default ranges for the learning rate: -3 to -1 / 2 in log10 units.
   - lightgbm, xgboost, catboost, and C5.0 have smaller default ranges for the sampling proportion: 0.5 to 1.0.
   - catboost engine arguments were added for `max_leaves` and `l2_leaf_reg`.