splitData helper added

lib/src/model_selection/exception/empty_ratio_collection_exception.dart

@@ -0,0 +1,4 @@
+class EmptyRatioCollectionException implements Exception {
+  @override
+  String toString() => 'Ratio collection must contain at least one element';
+}

lib/src/model_selection/exception/invalid_ratio_sum_exception.dart

@@ -0,0 +1,4 @@
+class InvalidRatioSumException implements Exception {
+  @override
+  String toString() => 'Ratios sum is equal to or more than 1';
+}

lib/src/model_selection/exception/outranged_ratio_exception.dart

@@ -0,0 +1,10 @@
+class OutRangedRatioException implements Exception {
+  OutRangedRatioException(double ratio)
+      : message = 'Ratio value must be within the range 0..1 (both exclusive), '
+      '$ratio given';
+
+  final String message;
+
+  @override
+  String toString() => message;
+}

lib/src/model_selection/exception/too_small_ratio_exception.dart

@@ -0,0 +1,10 @@
+class TooSmallRatioException implements Exception {
+  TooSmallRatioException(double ratio, int dataSize) :
+        message = 'Ratio is too small comparing to the input data size: ratio '
+            '$ratio, min ratio value ${(1 / dataSize).toStringAsFixed(2)}';
+
+  final String message;
+
+  @override
+  String toString() => message;
+}

lib/src/model_selection/split_data.dart

@@ -1,8 +1,12 @@
+import 'package:ml_algo/src/model_selection/exception/empty_ratio_collection_exception.dart';
+import 'package:ml_algo/src/model_selection/exception/invalid_ratio_sum_exception.dart';
+import 'package:ml_algo/src/model_selection/exception/outranged_ratio_exception.dart';
+import 'package:ml_algo/src/model_selection/exception/too_small_ratio_exception.dart';
 import 'package:ml_dataframe/ml_dataframe.dart';
 
-List<DataFrame> splitData(DataFrame data, Iterable<num> ratios) {
+List<DataFrame> splitData(DataFrame data, Iterable<double> ratios) {
   if (ratios.isEmpty) {
-    throw Exception('Ratio collection must contain at least one element');
+    throw EmptyRatioCollectionException();
   }
 
   final inputRows = data
@@ -14,22 +18,19 @@ List<DataFrame> splitData(DataFrame data, Iterable<num> ratios) {
   return ratios
       .map((ratio) {
         if (ratio <= 0 || ratio >= 1) {
-          throw Exception('Ratio value must be within the range 0..1 (both '
-              'exclusive), $ratio given');
+          throw OutRangedRatioException(ratio);
         }
 
         ratioSum += ratio;
 
         if (ratioSum >= 1) {
-          throw Exception('Ratios sum is more than or equal to 1');
+          throw InvalidRatioSumException();
         }
 
         final rawSplitSize = inputRows.length * ratio;
 
         if (rawSplitSize < 1) {
-          throw Exception('Ratio is too small comparing to the input data size: '
-              'ratio $ratio, min ratio value '
-              '${(1 / inputRows.length).toStringAsFixed(2)}');
+          throw TooSmallRatioException(ratio, inputRows.length);
         }
 
         final end = start + (rawSplitSize.ceil() == inputRows.length

test/model_selection/split_data_test.dart

@@ -1,3 +1,7 @@
+import 'package:ml_algo/src/model_selection/exception/empty_ratio_collection_exception.dart';
+import 'package:ml_algo/src/model_selection/exception/invalid_ratio_sum_exception.dart';
+import 'package:ml_algo/src/model_selection/exception/outranged_ratio_exception.dart';
+import 'package:ml_algo/src/model_selection/exception/too_small_ratio_exception.dart';
 import 'package:ml_algo/src/model_selection/split_data.dart';
 import 'package:ml_dataframe/ml_dataframe.dart';
 import 'package:test/test.dart';
@@ -15,26 +19,31 @@ void main() {
     ];
     final data = DataFrame(source);
 
-    test('should throw an exception if ratio list is empty', () {
-      expect(() => splitData(data, []), throwsException);
+    test('should throw an exception if ratio collection is empty', () {
+      expect(() => splitData(data, []),
+          throwsA(isA<EmptyRatioCollectionException>()));
     });
 
     test('should throw an exception if at least one ratio value is negative', () {
-      expect(() => splitData(data, [0.2, -0.3]), throwsException);
+      expect(() => splitData(data, [0.2, -0.3]),
+          throwsA(isA<OutRangedRatioException>()));
     });
 
     test('should throw an exception if at least one ratio value is zero', () {
-      expect(() => splitData(data, [0.2, 0]), throwsException);
+      expect(() => splitData(data, [0.2, 0]),
+          throwsA(isA<OutRangedRatioException>()));
     });
 
     test('should throw an exception if at least one ratio value is equal '
         'to 1', () {
-      expect(() => splitData(data, [1, 0.3]), throwsException);
+      expect(() => splitData(data, [1, 0.3]),
+          throwsA(isA<OutRangedRatioException>()));
     });
 
     test('should throw an exception if at least one ratio value is greater '
         'than 1', () {
-      expect(() => splitData(data, [100, 0.3]), throwsException);
+      expect(() => splitData(data, [100, 0.3]),
+          throwsA(isA<OutRangedRatioException>()));
     });
 
     test('should split data', () {
@@ -86,11 +95,13 @@ void main() {
     });
 
     test('should throw exception if there is a too small ratio, case 1', () {
-      expect(() => splitData(data, [0.2, 0.3, 0.01]), throwsException);
+      expect(() => splitData(data, [0.2, 0.3, 0.01]),
+          throwsA(isA<TooSmallRatioException>()));
     });
 
     test('should throw exception if there is a too small ratio, case 2', () {
-      expect(() => splitData(data, [0.2, 0.3, 0.1]), throwsException);
+      expect(() => splitData(data, [0.2, 0.3, 0.1]),
+          throwsA(isA<TooSmallRatioException>()));
     });
 
     test('should split data into two parts, first part is less than the '
@@ -171,22 +182,26 @@ void main() {
 
     test('should throw exception if ratios sum is equal to 1, '
         '2 elements', () {
-      expect(() => splitData(data, [0.5, 0.5]), throwsException);
+      expect(() => splitData(data, [0.5, 0.5]),
+          throwsA(isA<InvalidRatioSumException>()));
     });
 
     test('should throw exception if ratios sum is equal to 1, '
         '3 elements', () {
-      expect(() => splitData(data, [0.3, 0.3, 0.4]), throwsException);
+      expect(() => splitData(data, [0.3, 0.3, 0.4]),
+          throwsA(isA<InvalidRatioSumException>()));
     });
 
     test('should throw exception if ratios sum is greater than 1, '
         '2 elements', () {
-      expect(() => splitData(data, [0.5, 0.6]), throwsException);
+      expect(() => splitData(data, [0.5, 0.6]),
+          throwsA(isA<InvalidRatioSumException>()));
     });
 
     test('should throw exception if ratios sum is greater than 1, '
         '3 elements', () {
-      expect(() => splitData(data, [0.3, 0.5, 0.4]), throwsException);
+      expect(() => splitData(data, [0.3, 0.5, 0.4]),
+          throwsA(isA<InvalidRatioSumException>()));
     });
   });
 }