using System;
using System.Collections.Generic;
using Microsoft.ML;
using Microsoft.ML.Data;
 
namespace Samples.Dynamic
{
    public class MapKeyToVectorMultiColumn
    {
        /// This example demonstrates the use of MapKeyToVector by mapping keys to
        /// floats[] for multiple columns at once. Because the ML.NET KeyType maps
        /// the missing value to zero, counting starts at 1, so the uint values
        /// converted to KeyTypes will appear skewed by one.
        /// See https://github.com/dotnet/machinelearning/blob/main/docs/code/IDataViewTypeSystem.md#key-types
        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();
 
            // Get a small dataset as an IEnumerable.
            var rawData = new[] {
                new DataPoint() { Timeframe = 9, Category = 5 },
                new DataPoint() { Timeframe = 8, Category = 4 },
                new DataPoint() { Timeframe = 8, Category = 4 },
                new DataPoint() { Timeframe = 9, Category = 3 },
                new DataPoint() { Timeframe = 2, Category = 3 },
                new DataPoint() { Timeframe = 3, Category = 5 }
            };
 
            var data = mlContext.Data.LoadFromEnumerable(rawData);
 
            // Constructs the ML.net pipeline
            var pipeline = mlContext.Transforms.Conversion.MapKeyToVector(new[]{
                    new InputOutputColumnPair ("TimeframeVector", "Timeframe"),
                    new InputOutputColumnPair ("CategoryVector", "Category")
            });
 
            // Fits the pipeline to the data.
            IDataView transformedData = pipeline.Fit(data).Transform(data);
 
            // Getting the resulting data as an IEnumerable.
            // This will contain the newly created columns.
            IEnumerable<TransformedData> features = mlContext.Data.CreateEnumerable<
                TransformedData>(transformedData, reuseRowObject: false);
 
            Console.WriteLine($" Timeframe           TimeframeVector         " +
                $"Category    CategoryVector");
 
            foreach (var featureRow in features)
                Console.WriteLine(featureRow.Timeframe + "     " +
                    string.Join(',', featureRow.TimeframeVector) + "   " +
                    featureRow.Category + "      " +
                    string.Join(',', featureRow.CategoryVector));
 
            // TransformedData obtained post-transformation.
            //
            // Timeframe          TimeframeVector    Category    CategoryVector
            //  10              0,0,0,0,0,0,0,0,0,1       6          0,0,0,0,0
            //  9               0,0,0,0,0,0,0,0,1,0       5          0,0,0,0,1
            //  9               0,0,0,0,0,0,0,0,1,0       5          0,0,0,0,1
            //  10              0,0,0,0,0,0,0,0,0,1       4          0,0,0,1,0
            //  3               0,0,1,0,0,0,0,0,0,0       4          0,0,0,1,0
            //  4               0,0,0,1,0,0,0,0,0,0       6          0,0,0,0,0
        }
 
        private class DataPoint
        {
            // The maximal value used is 9; but since 0 is reserved for missing
            // value, we set the count to 10.
            [KeyType(10)]
            public uint Timeframe { get; set; }
 
            [KeyType(6)]
            public uint Category { get; set; }
 
        }
 
        private class TransformedData : DataPoint
        {
            public float[] TimeframeVector { get; set; }
            public float[] CategoryVector { get; set; }
        }
    }
}