add covert warning for multiclasslabel encoder

Author: LiuYuHui

src/shogun/labels/BinaryLabelEncoder.h

@@ -33,7 +33,7 @@ namespace shogun
 		{
 			const auto result_vector = labs->as<DenseLabels>()->get_labels();
 			check_is_valid(result_vector);
-			if (!can_convert_float_to_int(result_vector))
+			if (print_warning && !can_convert_float_to_int(result_vector))
 			{
 				io::warn(
 				    "({}, {}) have been converted to (-1, 1).",
@@ -122,19 +122,7 @@ namespace shogun
 			    fmt::join(unique_set, ", "));
 		}
 
-		bool can_convert_float_to_int(const SGVector<float64_t>& vec) const
-		{
-			SGVector<int32_t> converted(vec.vlen);
-			std::transform(
-			    vec.begin(), vec.end(), converted.begin(),
-			    [](auto&& e) { return static_cast<int32_t>(e); });
-			return std::equal(
-			    vec.begin(), vec.end(), converted.begin(),
-			    [](auto&& e1, auto&& e2) {
-				    return std::abs(e1 - e2) <
-				           std::numeric_limits<float64_t>::epsilon();
-			    });
-		}
+		
 	};
 } // namespace shogun
 

src/shogun/labels/LabelEncoder.h

@@ -59,6 +59,9 @@ namespace shogun
 			return "LabelEncoder";
 		}
 
+		void set_print_warning(bool print_warning){
+			print_warning = print_warning;
+		}
 	protected:
 		SGVector<float64_t> fit_impl(const SGVector<float64_t>& origin_vector)
 		{
@@ -98,6 +101,22 @@ namespace shogun
 			    });
 			return original_vector;
 		}
+
+		bool can_convert_float_to_int(const SGVector<float64_t>& vec) const
+		{
+			SGVector<int32_t> converted(vec.vlen);
+			std::transform(
+			    vec.begin(), vec.end(), converted.begin(),
+			    [](auto&& e) { return static_cast<int32_t>(e); });
+			return std::equal(
+			    vec.begin(), vec.end(), converted.begin(),
+			    [](auto&& e1, auto&& e2) {
+				    return std::abs(e1 - e2) <
+				           std::numeric_limits<float64_t>::epsilon();
+			    });
+		}
+
+		bool print_warning = true;
 		std::set<float64_t> unique_labels;
 		std::unordered_map<float64_t, float64_t> normalized_to_origin;
 	};

src/shogun/labels/MulticlassLabelsEncoder.h

@@ -32,6 +32,14 @@ namespace shogun
 		SGVector<float64_t> fit(const std::shared_ptr<Labels>& labs) override
 		{
 			const auto result_vector = labs->as<DenseLabels>()->get_labels();
+			if (print_warning && !can_convert_float_to_int(result_vector))
+			{	
+				std::set<float64_t> s(result_vector.begin(), result_vector.end());
+				io::warn(
+				    "{} have been converted to 0...{}", 
+						fmt::join(s, ", "),
+							 result_vector.vlen - 1);
+			}
 			return fit_impl(result_vector);
 		}
 		/** Transform labels to normalized encoding.