使用Linq首先对特定列值进行分组，然后对第二列中的值进行平均

using System.Linq;

// 假设我们有一个包含特定列和第二列的数据集
List<Data> dataList = new List<Data>
{
    new Data { Column1 = "A", Column2 = 10 },
    new Data { Column1 = "A", Column2 = 20 },
    new Data { Column1 = "B", Column2 = 30 },
    new Data { Column1 = "B", Column2 = 40 },
    new Data { Column1 = "C", Column2 = 50 },
};

// 使用Linq查询语法对特定列进行分组，并对第二列的值进行平均
var result = from data in dataList
             group data by data.Column1 into groupedData
             select new
             {
                 Column1 = groupedData.Key,
                 AverageColumn2 = groupedData.Average(d => d.Column2)
             };

// 遍历结果并输出
foreach (var item in result)
{
    Console.WriteLine($"Column1: {item.Column1}, AverageColumn2: {item.AverageColumn2}");
}