From 91429bd63d00fd090d9b74ddf8cdae9af6a5ebed Mon Sep 17 00:00:00 2001
From: Groves <Declan.Groves@allstate.com>
Date: Thu, 3 Dec 2015 06:40:11 -0600
Subject: [PATCH 1/2] Expose model parameters to R

---
 R-package/R/xgb.train.R | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/R-package/R/xgb.train.R b/R-package/R/xgb.train.R
index 768bed27b..d7fa6e1ee 100644
--- a/R-package/R/xgb.train.R
+++ b/R-package/R/xgb.train.R
@@ -140,6 +140,7 @@ xgb.train <- function(params=list(), data, nrounds, watchlist = list(),
     warning('watchlist is provided but verbose=0, no evaluation information will be printed')
   }
 
+  fit.call <- match.call()
   dot.params <- list(...)
   nms.params <- names(params)
   nms.dot.params <- names(dot.params)
@@ -224,9 +225,13 @@ xgb.train <- function(params=list(), data, nrounds, watchlist = list(),
     }
   }
   bst <- xgb.Booster.check(bst)
+
   if (!is.null(early.stop.round)) {
     bst$bestScore <- bestScore
     bst$bestInd <- bestInd
   }
+
+  attr(bst, "call") <- fit.call
+  attr(bst, "params") <- params
   return(bst)
 }

From cd57ea27844c0e40065b7ec516d9c71067947e08 Mon Sep 17 00:00:00 2001
From: Groves <Declan.Groves@allstate.com>
Date: Wed, 16 Dec 2015 10:24:16 -0600
Subject: [PATCH 2/2] Add test that model paramaters are accessible within R

---
 .../tests/testthat/test_parameter_exposure.R  | 32 +++++++++++++++++++
 1 file changed, 32 insertions(+)
 create mode 100644 R-package/tests/testthat/test_parameter_exposure.R

diff --git a/R-package/tests/testthat/test_parameter_exposure.R b/R-package/tests/testthat/test_parameter_exposure.R
new file mode 100644
index 000000000..769059b76
--- /dev/null
+++ b/R-package/tests/testthat/test_parameter_exposure.R
@@ -0,0 +1,32 @@
+context('Test model params and call are exposed to R')
+
+require(xgboost)
+
+data(agaricus.train, package='xgboost')
+data(agaricus.test, package='xgboost')
+
+dtrain <- xgb.DMatrix(agaricus.train$data, label = agaricus.train$label)
+dtest <- xgb.DMatrix(agaricus.test$data, label = agaricus.test$label)
+
+bst <- xgboost(data = dtrain,
+               max.depth = 2,
+               eta = 1,
+               nround = 10,
+               nthread = 1,
+               verbose = 0,
+               objective = "binary:logistic")
+
+test_that("call is exposed to R", {
+  model_call <- attr(bst, "call")
+  expect_is(model_call, "call")
+})
+
+test_that("params is exposed to R", {
+  model_params <- attr(bst, "params")
+
+  expect_is(model_params, "list")
+
+  expect_equal(model_params$eta, 1)
+  expect_equal(model_params$max.depth, 2)
+  expect_equal(model_params$objective, "binary:logistic")
+})