From dbf017afd9eae11d392104c3240c81e2d9b7765c Mon Sep 17 00:00:00 2001
From: Senja Filipi <sfilipi@users.noreply.github.com>
Date: Mon, 15 Apr 2019 14:09:51 -0700
Subject: [PATCH] Towards #3204 - ColumCopying documentation  (#3316)

* applying the #3204 template to ColumnCopying.
---
 .../Transforms/ColumnCopying.cs               | 23 ++++++++++++++++++-
 .../Transforms/ExtensionsCatalog.cs           | 18 +++++++++------
 2 files changed, 33 insertions(+), 8 deletions(-)

diff --git a/src/Microsoft.ML.Data/Transforms/ColumnCopying.cs b/src/Microsoft.ML.Data/Transforms/ColumnCopying.cs
index 3c9b2eef51..63f4cf5d69 100644
--- a/src/Microsoft.ML.Data/Transforms/ColumnCopying.cs
+++ b/src/Microsoft.ML.Data/Transforms/ColumnCopying.cs
@@ -31,8 +31,26 @@
 namespace Microsoft.ML.Transforms
 {
     /// <summary>
-    /// <see cref="ColumnCopyingEstimator"/> copies the input column to another column named as specified in the parameters of the transformation.
+    /// <see cref="IEstimator{TTransformer}"/> for the <see cref="ColumnCopyingTransformer"/>.
     /// </summary>
+    /// <remarks>
+    /// <format type="text/markdown"><![CDATA[
+    ///
+    /// ###  Estimator Characteristics
+    /// |  |  |
+    /// | -- | -- |
+    /// | Does this estimator need to look at the data to train its parameters? | No |
+    /// | Input column data type | Any |
+    /// | Output column data type | The same as the data type in the input column |
+    ///
+    /// The resulting <see cref="ColumnCopyingTransformer"/> creates a new column, named as specified in the output column name parameters, and
+    /// copies the data from the input column to this new column.
+    /// See the See Also section for links to examples of the usage.
+    /// ]]>
+    /// </format>
+    /// </remarks>
+    /// <seealso cref="TransformExtensionsCatalog.CopyColumns(TransformsCatalog, InputOutputColumnPair[])" />
+    /// <seealso cref="TransformExtensionsCatalog.CopyColumns(TransformsCatalog, string, string)" />
     public sealed class ColumnCopyingEstimator : TrivialEstimator<ColumnCopyingTransformer>
     {
         [BestFriend]
@@ -67,6 +85,9 @@ public override SchemaShape GetOutputSchema(SchemaShape inputSchema)
         }
     }
 
+    /// <summary>
+    /// <see cref="ITransformer"/> resulting from fitting an <see cref="ColumnCopyingEstimator"/>.
+    /// </summary>
     public sealed class ColumnCopyingTransformer : OneToOneTransformerBase
     {
         [BestFriend]
diff --git a/src/Microsoft.ML.Data/Transforms/ExtensionsCatalog.cs b/src/Microsoft.ML.Data/Transforms/ExtensionsCatalog.cs
index ac0a7ec14d..de8ad69e96 100644
--- a/src/Microsoft.ML.Data/Transforms/ExtensionsCatalog.cs
+++ b/src/Microsoft.ML.Data/Transforms/ExtensionsCatalog.cs
@@ -51,11 +51,14 @@ internal static IReadOnlyList<InputOutputColumnPair> ConvertFromValueTuples((str
     public static class TransformExtensionsCatalog
     {
         /// <summary>
-        /// Copies the input column to another column named as specified in <paramref name="outputColumnName"/>.
+        /// Create a <see cref="ColumnCopyingEstimator"/>, which copies the data from the column specified in <paramref name="inputColumnName"/>
+        /// to a new column: <paramref name="outputColumnName"/>.
         /// </summary>
         /// <param name="catalog">The transform's catalog.</param>
-        /// <param name="outputColumnName">Name of the column resulting from the transformation of <paramref name="inputColumnName"/>.</param>
-        /// <param name="inputColumnName">Name of the columns to transform.</param>
+        /// <param name="outputColumnName">Name of the column resulting from the transformation of <paramref name="inputColumnName"/>.
+        /// This column's data type will be the same as that of the input column.</param>
+        /// <param name="inputColumnName">Name of the column to copy the data from.
+        /// This estimator operates over any data type.</param>
         /// <example>
         /// <format type="text/markdown">
         /// <![CDATA[
@@ -67,11 +70,12 @@ public static ColumnCopyingEstimator CopyColumns(this TransformsCatalog catalog,
             => new ColumnCopyingEstimator(CatalogUtils.GetEnvironment(catalog), outputColumnName, inputColumnName);
 
         /// <summary>
-        /// Copies the input column, name specified in the first item of the tuple,
-        /// to another column, named as specified in the second item of the tuple.
+        /// Create a <see cref="ColumnCopyingEstimator"/>, which copies the data from the column specified in <see cref="InputOutputColumnPair.InputColumnName" />
+        /// to a new column: <see cref="InputOutputColumnPair.OutputColumnName" />.
         /// </summary>
-        /// <param name="catalog">The transform's catalog</param>
-        /// <param name="columns">The pairs of input and output columns.</param>
+        /// <remarks>This transform can operate over several columns.</remarks>
+        /// <param name="catalog">The transform's catalog.</param>
+        /// <param name="columns">The pairs of input and output columns. This estimator operates over any data type.</param>
         /// <example>
         /// <format type="text/markdown">
         /// <![CDATA[