Sample for ConvertType transform estimator (#2781)

* adding sample for ConvertType

* remove unnecessary row

* taking care of review comments

* moving sample file so we mirror to the catalog access path

Author: abgoswam

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

@@ -0,0 +1,55 @@
+using System;
+using Microsoft.ML.Data;
+
+namespace Microsoft.ML.Samples.Dynamic
+{
+    public static class ConvertType
+    {
+        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,-10}  Aconv:{1}", item.Survived, item.SurvivedInt32);
+            }
+
+            // Output
+            // A: True     Aconv:1
+            // A: False    Aconv:0
+            // A: True     Aconv:1
+            // A: False    Aconv:0
+            // A: False    Aconv:0
+        }
+    }
+}

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;

src/Microsoft.ML.Data/Transforms/ConversionsExtensionsCatalog.cs

@@ -47,6 +47,12 @@ public static HashingEstimator Hash(this TransformsCatalog.ConversionTransforms
         /// <param name="outputColumnName">Name of the column resulting from the transformation of <paramref name="inputColumnName"/>.</param>
         /// <param name="inputColumnName">Name of the column to transform. If set to <see langword="null"/>, the value of the <paramref name="outputColumnName"/> will be used as source.</param>
         /// <param name="outputKind">The expected kind of the output column.</param>
+        /// <example>
+        /// <format type="text/markdown">
+        /// <![CDATA[
+        ///  [!code-csharp[ConvertType](~/../docs/samples/docs/samples/Microsoft.ML.Samples/Dynamic/Transforms/Conversion/ConvertType.cs)]
+        /// ]]></format>
+        /// </example>
         public static TypeConvertingEstimator ConvertType(this TransformsCatalog.ConversionTransforms catalog, string outputColumnName, string inputColumnName = null,
             DataKind outputKind = ConvertDefaults.DefaultOutputKind)
             => new TypeConvertingEstimator(CatalogUtils.GetEnvironment(catalog), outputColumnName, inputColumnName, outputKind);

test/BaselineOutput/Common/Convert/Types.tsv

@@ -24,6 +24,7 @@
 #@   col=ConvL:R4:42-43
 #@   col=ConvM:R4:44-45
 #@   col=ConvN:R4:46-47
+#@   col=ConvBI:I4:48-49
 #@ }
-a	b	0	1	-1	1	0	1	0	1	-1	1	-1	1	0	1	-1	1	0	1	1	1	1	1	?	?	0	1	-1	1	0	1	0	1	-1	1	-1	1	0	1	-1	1	0	1	1	1	1	1
-0	1	0	1	-2147483648	2147483647	0	4294967295	0	255	-128	127	-32768	32767	0	65535	-9223372036854775808	9223372036854775807	0	18446744073709551615	-3.40282347E+38	3.40282347E+38	-1.7976931348623157E+308	1.7976931348623157E+308	0	1	0	1	-2.14748365E+09	2.14748365E+09	0	4.2949673E+09	0	255	-128	127	-32768	32767	0	65535	-9.223372E+18	9.223372E+18	0	1.84467441E+19	-3.40282347E+38	3.40282347E+38	-Infinity	Infinity
+a	b	0	1	-1	1	0	1	0	1	-1	1	-1	1	0	1	-1	1	0	1	1	1	1	1	?	?	0	1	-1	1	0	1	0	1	-1	1	-1	1	0	1	-1	1	0	1	1	1	1	1	0	1
+0	1	1	0	-2147483648	2147483647	0	4294967295	0	255	-128	127	-32768	32767	0	65535	-9223372036854775808	9223372036854775807	0	18446744073709551615	-3.40282347E+38	3.40282347E+38	-1.7976931348623157E+308	1.7976931348623157E+308	0	1	1	0	-2.14748365E+09	2.14748365E+09	0	4.2949673E+09	0	255	-128	127	-32768	32767	0	65535	-9.223372E+18	9.223372E+18	0	1.84467441E+19	-3.40282347E+38	3.40282347E+38	-Infinity	Infinity	1	0

test/Microsoft.ML.Tests/Transformers/ConvertTests.cs

@@ -98,7 +98,7 @@ public void TestConvertWorkout()
                   new TestPrimitiveClass()
                 {
                     AA = new []{"0", "1"},
-                    AB = new []{false, true},
+                    AB = new []{true, false},
                     AC = new []{ int.MinValue, int.MaxValue},
                     AD = new uint[]{ uint.MinValue, uint.MaxValue},
                     AE = new byte[]{ byte.MinValue, byte.MaxValue},
@@ -125,7 +125,9 @@ public void TestConvertWorkout()
                 new TypeConvertingEstimator.ColumnOptions("ConvK", DataKind.Single, "AK"),
                 new TypeConvertingEstimator.ColumnOptions("ConvL", DataKind.Single, "AL"),
                 new TypeConvertingEstimator.ColumnOptions("ConvM", DataKind.Single, "AM"),
-                new TypeConvertingEstimator.ColumnOptions("ConvN", DataKind.Single, "AN")}
+                new TypeConvertingEstimator.ColumnOptions("ConvN", DataKind.Single, "AN"),
+                new TypeConvertingEstimator.ColumnOptions("ConvBI", DataKind.Int32, "AB") // verify Boolean -> Int32 conversion
+            }
             );
             TestEstimatorCore(allTypesPipe, allTypesDataView);