Rev OVA pipeline node SDK output: wrap binary trainers as children inside parent OVA node (dotnet#317)

Author: daholste

src/Microsoft.ML.Auto/TrainerExtensions/TrainerExtensionUtil.cs

@@ -32,6 +32,7 @@ internal enum TrainerName
         LogisticRegressionMulti,
         OnlineGradientDescentRegression,
         OrdinaryLeastSquaresRegression,
+        Ova,
         PoissonRegression,
         SdcaBinary,
         SdcaMulti,
@@ -79,8 +80,17 @@ public static LightGBM.Options CreateLightGbmOptions(IEnumerable<SweepableParam>
         public static PipelineNode BuildOvaPipelineNode(ITrainerExtension multiExtension, ITrainerExtension binaryExtension,
             IEnumerable<SweepableParam> sweepParams, ColumnInformation columnInfo)
         {
-            var ovaNode = binaryExtension.CreatePipelineNode(sweepParams, columnInfo);
-            ovaNode.Name = TrainerExtensionCatalog.GetTrainerName(multiExtension).ToString();
+            var ovaNode = new PipelineNode()
+            {
+                Name = TrainerName.Ova.ToString(),
+                NodeType = PipelineNodeType.Trainer,
+                Properties = new Dictionary<string, object>()
+                {
+                    { LabelColumn, columnInfo.LabelColumn }
+                }
+            };
+            var binaryNode = binaryExtension.CreatePipelineNode(sweepParams, columnInfo);
+            ovaNode.Properties["BinaryTrainer"] = binaryNode;
             return ovaNode;
         }
 

src/Test/TrainerExtensionsTests.cs

@@ -17,7 +17,8 @@ public void TrainerExtensionInstanceTests()
         {
             var context = new MLContext();
             var columnInfo = new ColumnInformation();
-            var trainerNames = Enum.GetValues(typeof(TrainerName)).Cast<TrainerName>();
+            var trainerNames = Enum.GetValues(typeof(TrainerName)).Cast<TrainerName>()
+                .Except(new[] { TrainerName.Ova });
             foreach (var trainerName in trainerNames)
             {
                 var extension = TrainerExtensionCatalog.GetTrainerExtension(trainerName);
@@ -194,16 +195,25 @@ public void BuildOvaPipelineNode()
         {
             var pipelineNode = new FastForestOvaExtension().CreatePipelineNode(null, new ColumnInformation());
             var expectedJson = @"{
-  ""Name"": ""FastForestOva"",
+  ""Name"": ""Ova"",
   ""NodeType"": ""Trainer"",
-  ""InColumns"": [
-    ""Features""
-  ],
-  ""OutColumns"": [
-    ""Score""
-  ],
+  ""InColumns"": null,
+  ""OutColumns"": null,
   ""Properties"": {
-    ""LabelColumn"": ""Label""
+    ""LabelColumn"": ""Label"",
+    ""BinaryTrainer"": {
+      ""Name"": ""FastForestBinary"",
+      ""NodeType"": ""Trainer"",
+      ""InColumns"": [
+        ""Features""
+      ],
+      ""OutColumns"": [
+        ""Score""
+      ],
+      ""Properties"": {
+        ""LabelColumn"": ""Label""
+      }
+    }
   }
 }";
             Util.AssertObjectMatchesJson(expectedJson, pipelineNode);