C# winform 直线拟合示例带画图

以下是一个 C# WinForms 直线拟合示例程序，可以绘制数据点和拟合的直线：

using System;
using System.Collections.Generic;
using System.Drawing;
using System.Linq;
using System.Windows.Forms;

namespace LinearRegressionExample
{
    public partial class Form1 : Form
    {
        private List<double> xValues = new List<double>();
        private List<double> yValues = new List<double>();
        private double slope = 0;
        private double intercept = 0;

        public Form1()
        {
            InitializeComponent();
        }

        private void Form1_Load(object sender, EventArgs e)
        {
            // 初始化绘图控件
            chart1.Series.Clear();
            chart1.Series.Add("Data");
            chart1.Series.Add("Line");
            chart1.Series["Data"].ChartType = System.Windows.Forms.DataVisualization.Charting.SeriesChartType.Point;
            chart1.Series["Line"].ChartType = System.Windows.Forms.DataVisualization.Charting.SeriesChartType.Line;
            chart1.Series["Line"].Color = Color.Red;
        }

        private void btnAddData_Click(object sender, EventArgs e)
        {
            double x, y;
            if (!double.TryParse(txtX.Text, out x) || !double.TryParse(txtY.Text, out y))
            {
                MessageBox.Show("Invalid input!");
                return;
            }

            xValues.Add(x);
            yValues.Add(y);

            chart1.Series["Data"].Points.Add(new DataPoint(x, y));
        }

        private void btnClearData_Click(object sender, EventArgs e)
        {
            xValues.Clear();
            yValues.Clear();
            chart1.Series["Data"].Points.Clear();
            chart1.Series["Line"].Points.Clear();
        }

        private void btnFitLine_Click(object sender, EventArgs e)
        {
            if (xValues.Count != yValues.Count || xValues.Count < 2)
            {
                MessageBox.Show("Invalid data!");
                return;
            }

            // 计算平均值
            double xAvg = xValues.Average();
            double yAvg = yValues.Average();

            // 求斜率和截距
            slope = xValues.Zip(yValues, (x, y) => (x - xAvg) * (y - yAvg)).Sum()
                / xValues.Zip(xValues, (x1, x2) => (x1 - xAvg) * (x2 - xAvg)).Sum();
            intercept = yAvg - slope * xAvg;

            // 绘制拟合直线
            chart1.Series["Line"].Points.Clear();
            chart1.Series["Line"].Points.Add(new DataPoint(xValues.Min(), slope * xValues.Min() + intercept));
            chart1.Series["Line"].Points.Add(new DataPoint(xValues.Max(), slope * xValues.Max() + intercept));
        }

        private void chart1_PostPaint(object sender, ChartPaintEventArgs e)
        {
            // 绘制斜率和截距
            if (xValues.Count > 0 && yValues.Count > 0)
            {
                Graphics g = e.ChartGraphics.Graphics;
                g.DrawString($"y={slope:N2}x+{intercept:N2}", Font, Brushes.Black, new PointF(10, 10));
            }
        }
    }
}

这个程序使用 `System.Windows.Forms.DataVisualization.Charting` 组件绘制图形，需要在项目中添加对该组件的引用。在窗体上放置一个 `Chart` 控件，以及一些按钮和文本框。用户可以在文本框中输入数据点，点击“Add Data”按钮添加到图表中；点击“Clear Data”按钮清除所有数据点；点击“Fit Line”按钮进行线性回归并绘制拟合的直线。拟合结果会显示在图表上。