Sample for ConvertType transform estimator

docs/samples/Microsoft.ML.Samples/Dynamic/ConvertType.cs

@@ -0,0 +1,48 @@
+using System;
+using Microsoft.ML.Data;
+
+namespace Microsoft.ML.Samples.Dynamic
+{
+    public static class ConvertTypeTransform
+    {
+        private sealed class InputData
+        {
+            public bool Survived;
+        }
+
+        private sealed class TransformedData
+        {
+            public bool Survived { get; set; }
+
+            public Int32 SurvivedInt32 { get; set; }
+        }
+
+        public static void Example()
+        {
+            var mlContext = new MLContext(seed: 1, conc: 1);
+            var rawData = new[] {
+                new InputData() { Survived = true },
+                new InputData() { Survived = false },
+                new InputData() { Survived = true },
+                new InputData() { Survived = false },
+                new InputData() { Survived = false },
+            };
+
+            var data = mlContext.Data.LoadFromEnumerable(rawData);
+
+            // Construct the pipeline.
+            var pipeline = mlContext.Transforms.Conversion.ConvertType("SurvivedInt32", "Survived", DataKind.Int32);
+
+            // Let's train our pipeline, and then apply it to the same data.
+            var transformer = pipeline.Fit(data);
+            var transformedData = transformer.Transform(data);
+
+            // Display original column 'Survived' (boolean) and converted column 'SurvivedInt32' (Int32)
+            var convertedData = mlContext.Data.CreateEnumerable<TransformedData>(transformedData, true);
+            foreach (var item in convertedData)
+            {
+                Console.WriteLine("A:{0}  Aconv:{1}", item.Survived, item.SurvivedInt32);
+            }
+        }
+    }
+}

src/Microsoft.ML.Data/Data/Conversion.cs

@@ -1642,10 +1642,10 @@ public void Convert(in TX src, ref SB dst)
         #endregion FromTX
 
         #region FromBL
-        public void Convert(in BL src, ref I1 dst) => dst = (I1)(object)src;
-        public void Convert(in BL src, ref I2 dst) => dst = (I2)(object)src;
-        public void Convert(in BL src, ref I4 dst) => dst = (I4)(object)src;
-        public void Convert(in BL src, ref I8 dst) => dst = (I8)(object)src;
+        public void Convert(in BL src, ref I1 dst) => dst = System.Convert.ToSByte(src);
+        public void Convert(in BL src, ref I2 dst) => dst = System.Convert.ToInt16(src);
+        public void Convert(in BL src, ref I4 dst) => dst = System.Convert.ToInt32(src);
+        public void Convert(in BL src, ref I8 dst) => dst = System.Convert.ToInt64(src);
         public void Convert(in BL src, ref R4 dst) => dst = System.Convert.ToSingle(src);
         public void Convert(in BL src, ref R8 dst) => dst = System.Convert.ToDouble(src);
         public void Convert(in BL src, ref BL dst) => dst = src;