ML.NET 机器学习 教程 线性回归模型 模型保存及加载

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using Microsoft.ML;
using Microsoft.ML.Data;


namespace MLApp
{
    internal class Program
    {
        public class HouseData
        {
            public float Size { get; set; }
            public float Price { get; set; }
        }

        public class Prediction
        {
            [ColumnName("Score")]
            public float Price { get; set; }
        }

        static void Main(string[] args)
        {
            MLContext mlContext = new MLContext();

            // 1. Import or create training data
            HouseData[] houseData = {
               new HouseData() { Size = 1.1F, Price = 1.2F },
               new HouseData() { Size = 1.9F, Price = 2.3F },
               new HouseData() { Size = 2.8F, Price = 3.0F },
               new HouseData() { Size = 3.4F, Price = 3.7F } };
            IDataView trainingData = mlContext.Data.LoadFromEnumerable(houseData);

            // 2. Specify data preparation and model training pipeline
            var pipeline = mlContext.Transforms.Concatenate("Features", new[] { "Size" }).Append(mlContext.Regression.Trainers.Sdca(labelColumnName: "Price", maximumNumberOfIterations: 100));

            // 3. Train model
            var model = pipeline.Fit(trainingData);

            // 保存模型
            string modelPath = Path.Combine(Environment.CurrentDirectory, "TestModel.zip");
            mlContext.Model.Save(model, trainingData.Schema, modelPath);
            // 加载模型
            ITransformer model_load = mlContext.Model.Load(modelPath, out var schema);

            // 4. Make a prediction
            var size = new HouseData() { Size = 2.5F };
            // 方式1
            var price = mlContext.Model.CreatePredictionEngine<HouseData, Prediction>(model).Predict(size);
            // $作用是将{}内容当做表达式。  C 货币。
            Console.WriteLine($" 直接预测 Predicted price for size: {size.Size * 1000} sq ft= {price.Price * 100:C}k");

            // 方式2
            var price_load = mlContext.Model.CreatePredictionEngine<HouseData, Prediction>(model_load).Predict(size);
            // $作用是将{}内容当做表达式。  C 货币。
            Console.WriteLine($" 加载模型预测 Predicted price for size: {size.Size * 1000} sq ft= {price_load.Price * 100:C}k");

            // Predicted price for size: 2500 sq ft= $261.98k

            // 等待用户按下任意键。避免窗口关闭。
            Console.ReadKey();
        }
    }
}