Created sample for text normalizing API. (dotnet#3133)

Author: zeahmed

docs/samples/Microsoft.ML.Samples/Dynamic/Transforms/Text/NormalizeText.cs

@@ -0,0 +1,57 @@
+using System;
+using System.Collections.Generic;
+using System.Text;
+
+namespace Microsoft.ML.Samples.Dynamic
+{
+    public static class NormalizeText
+    {
+        public static void Example()
+        {
+            // Create a new ML context, for ML.NET operations. It can be used for exception tracking and logging, 
+            // as well as the source of randomness.
+            var mlContext = new MLContext();
+
+            // Create an empty data sample list. The 'NormalizeText' API does not require training data as
+            // the estimator ('TextNormalizingEstimator') created by 'NormalizeText' API is not a trainable estimator.
+            // The empty list is only needed to pass input schema to the pipeline.
+            var emptySamples = new List<TextData>();
+
+            // Convert sample list to an empty IDataView.
+            var emptyDataView = mlContext.Data.LoadFromEnumerable(emptySamples);
+
+            // A pipeline for normalizing text.
+            var normTextPipeline = mlContext.Transforms.Text.NormalizeText("NormalizedText", "Text",
+                Transforms.Text.TextNormalizingEstimator.CaseMode.Lower,
+                keepDiacritics: false,
+                keepPunctuations: false,
+                keepNumbers: false);
+
+            // Fit to data.
+            var normTextTransformer = normTextPipeline.Fit(emptyDataView);
+
+            // Create the prediction engine to get the normalized text from the input text/string.
+            var predictionEngine = mlContext.Model.CreatePredictionEngine<TextData, TransformedTextData>(normTextTransformer);
+
+            // Call the prediction API.
+            var data = new TextData() { Text = "ML.NET's NormalizeText API changes the case of the TEXT and removes/keeps diâcrîtîcs, punctuations, and/or numbers (123)." };
+            var prediction = predictionEngine.Predict(data);
+
+            // Print the normalized text.
+            Console.WriteLine($"Normalized Text: {prediction.NormalizedText}");
+
+            //  Expected output:
+            //   Normalized Text: mlnets normalizetext api changes the case of the text and removeskeeps diacritics punctuations andor numbers
+        }
+
+        public class TextData
+        {
+            public string Text { get; set; }
+        }
+
+        public class TransformedTextData : TextData
+        {
+            public string NormalizedText { get; set; }
+        }
+    }
+}

src/Microsoft.ML.Transforms/Text/TextCatalog.cs

@@ -107,6 +107,13 @@ internal static TokenizingByCharactersEstimator TokenizeIntoCharactersAsKeys(thi
         /// <param name="keepDiacritics">Whether to keep diacritical marks or remove them.</param>
         /// <param name="keepPunctuations">Whether to keep punctuation marks or remove them.</param>
         /// <param name="keepNumbers">Whether to keep numbers or remove them.</param>
+        /// <example>
+        /// <format type="text/markdown">
+        /// <![CDATA[
+        /// [!code-csharp[NormalizeText](~/../docs/samples/docs/samples/Microsoft.ML.Samples/Dynamic/Transforms/Text/NormalizeText.cs)]
+        /// ]]>
+        /// </format>
+        /// </example>
         public static TextNormalizingEstimator NormalizeText(this TransformsCatalog.TextTransforms catalog,
             string outputColumnName,
             string inputColumnName = null,