[R-package] Merge iterations and early stopping with params (#829)

* Prepare merging parameters

* Add parameters from params for lgb.train

* Usage of params in lgb.cv for rounds/early stop

* Double bracket (1)

* Double brackets (2)

R-package/R/lgb.cv.R

@@ -137,7 +137,12 @@ lgb.cv <- function(params = list(),
   if (!is.null(predictor)) {
     begin_iteration <- predictor$current_iter() + 1
   }
+  # Check for number of rounds passed as parameter - in case there are multiple ones, take only the first one
+  if (sum(names(params) %in% c("num_iterations", "num_iteration", "num_tree", "num_trees", "num_round", "num_rounds")) > 0) {
+    end_iteration <- begin_iteration + params[[which(names(params) %in% c("num_iterations", "num_iteration", "num_tree", "num_trees", "num_round", "num_rounds"))[1]]] - 1
+  } else {
     end_iteration <- begin_iteration + nrounds - 1
+  }
   
   # Check for training dataset type correctness
   if (!lgb.is.Dataset(data)) {
@@ -209,12 +214,18 @@ lgb.cv <- function(params = list(),
     callbacks <- add.cb(callbacks, cb.record.evaluation())
   }
   
-  # Add early stopping callback
+  # Check for early stopping passed as parameter when adding early stopping callback
+  if (sum(names(params) %in% c("early_stopping_round", "early_stopping_rounds", "early_stopping")) > 0) {
+    if (params[[which(names(params) %in% c("early_stopping_round", "early_stopping_rounds", "early_stopping"))[1]]] > 0) {
+      callbacks <- add.cb(callbacks, cb.early.stop(params[[which(names(params) %in% c("early_stopping_round", "early_stopping_rounds", "early_stopping"))[1]]], verbose = verbose))
+    }
+  } else {
     if (!is.null(early_stopping_rounds)) {
       if (early_stopping_rounds > 0) {
         callbacks <- add.cb(callbacks, cb.early.stop(early_stopping_rounds, verbose = verbose))
       }
     }
+  }
   
   # Categorize callbacks
   cb <- categorize.callbacks(callbacks)

R-package/R/lgb.train.R

@@ -112,7 +112,13 @@ lgb.train <- function(params = list(),
   if (!is.null(predictor)) {
     begin_iteration <- predictor$current_iter() + 1
   }
+  # Check for number of rounds passed as parameter - in case there are multiple ones, take only the first one
+  if (sum(names(params) %in% c("num_iterations", "num_iteration", "num_tree", "num_trees", "num_round", "num_rounds")) > 0) {
+    end_iteration <- begin_iteration + params[[which(names(params) %in% c("num_iterations", "num_iteration", "num_tree", "num_trees", "num_round", "num_rounds"))[1]]] - 1
+  } else {
     end_iteration <- begin_iteration + nrounds - 1
+  }
+  
   
   # Check for training dataset type correctness
   if (!lgb.is.Dataset(data)) {
@@ -195,12 +201,18 @@ lgb.train <- function(params = list(),
     callbacks <- add.cb(callbacks, cb.record.evaluation())
   }
   
-  # Add early stopping callback
+  # Check for early stopping passed as parameter when adding early stopping callback
+  if (sum(names(params) %in% c("early_stopping_round", "early_stopping_rounds", "early_stopping")) > 0) {
+    if (params[[which(names(params) %in% c("early_stopping_round", "early_stopping_rounds", "early_stopping"))[1]]] > 0) {
+      callbacks <- add.cb(callbacks, cb.early.stop(params[[which(names(params) %in% c("early_stopping_round", "early_stopping_rounds", "early_stopping"))[1]]], verbose = verbose))
+    }
+  } else {
     if (!is.null(early_stopping_rounds)) {
       if (early_stopping_rounds > 0) {
         callbacks <- add.cb(callbacks, cb.early.stop(early_stopping_rounds, verbose = verbose))
       }
     }
+  }
   
   # "Categorize" callbacks
   cb <- categorize.callbacks(callbacks)