[R-package] avoid misleading warnings when using interaction constraints (fixes #4108) (#4232)

R-package/R/lgb.cv.R

@@ -166,6 +166,11 @@ lgb.cv <- function(params = list()
   }
   end_iteration <- begin_iteration + params[["num_iterations"]] - 1L
 
+  # pop interaction_constraints off of params. It needs some preprocessing on the
+  # R side before being passed into the Dataset object
+  interaction_constraints <- params[["interaction_constraints"]]
+  params["interaction_constraints"] <- NULL
+
   # Construct datasets, if needed
   data$update_params(params = params)
   data$construct()
@@ -177,7 +182,10 @@ lgb.cv <- function(params = list()
   } else if (!is.null(data$get_colnames())) {
     cnames <- data$get_colnames()
   }
-  params[["interaction_constraints"]] <- lgb.check_interaction_constraints(params = params, column_names = cnames)
+  params[["interaction_constraints"]] <- lgb.check_interaction_constraints(
+    interaction_constraints = interaction_constraints
+    , column_names = cnames
+  )
 
   # Check for weights
   if (!is.null(weight)) {

R-package/R/lgb.train.R

@@ -144,6 +144,11 @@ lgb.train <- function(params = list(),
   }
   end_iteration <- begin_iteration + params[["num_iterations"]] - 1L
 
+  # pop interaction_constraints off of params. It needs some preprocessing on the
+  # R side before being passed into the Dataset object
+  interaction_constraints <- params[["interaction_constraints"]]
+  params["interaction_constraints"] <- NULL
+
   # Construct datasets, if needed
   data$update_params(params = params)
   data$construct()
@@ -156,7 +161,7 @@ lgb.train <- function(params = list(),
     cnames <- data$get_colnames()
   }
   params[["interaction_constraints"]] <- lgb.check_interaction_constraints(
-    params = params
+    interaction_constraints = interaction_constraints
     , column_names = cnames
   )
 

R-package/R/utils.R

@@ -168,21 +168,21 @@ lgb.params2str <- function(params, ...) {
 
 }
 
-lgb.check_interaction_constraints <- function(params, column_names) {
+lgb.check_interaction_constraints <- function(interaction_constraints, column_names) {
 
   # Convert interaction constraints to feature numbers
   string_constraints <- list()
 
-  if (!is.null(params[["interaction_constraints"]])) {
+  if (!is.null(interaction_constraints)) {
 
-    if (!methods::is(params[["interaction_constraints"]], "list")) {
+    if (!methods::is(interaction_constraints, "list")) {
         stop("interaction_constraints must be a list")
     }
-    if (!all(sapply(params[["interaction_constraints"]], function(x) {is.character(x) || is.numeric(x)}))) {
+    if (!all(sapply(interaction_constraints, function(x) {is.character(x) || is.numeric(x)}))) {
         stop("every element in interaction_constraints must be a character vector or numeric vector")
     }
 
-    for (constraint in params[["interaction_constraints"]]) {
+    for (constraint in interaction_constraints) {
 
       # Check for character name
       if (is.character(constraint)) {