Linq按两个字段分组并取平均值

// 假设有一个包含学生信息的类 Student，其中包括Name、Subject和Score属性

// 数据源
List<Student> students = new List<Student>
{
    new Student { Name = "Alice", Subject = "Math", Score = 85 },
    new Student { Name = "Bob", Subject = "Math", Score = 92 },
    new Student { Name = "Alice", Subject = "English", Score = 78 },
    new Student { Name = "Bob", Subject = "English", Score = 88 },
    new Student { Name = "Alice", Subject = "Science", Score = 90 },
    new Student { Name = "Bob", Subject = "Science", Score = 95 }
};

// 使用LINQ进行分组和计算平均值
var result = from student in students
             group student by new { student.Name, student.Subject } into g
             select new
             {
                 Name = g.Key.Name,
                 Subject = g.Key.Subject,
                 AverageScore = g.Average(s => s.Score)
             };

// 输出结果
foreach (var item in result)
{
    Console.WriteLine($"Name: {item.Name}, Subject: {item.Subject}, Average Score: {item.AverageScore}");
}

Name: Alice, Subject: Math, Average Score: 85
Name: Bob, Subject: Math, Average Score: 92
Name: Alice, Subject: English, Average Score: 78
Name: Bob, Subject: English, Average Score: 88
Name: Alice, Subject: Science, Average Score: 90
Name: Bob, Subject: Science, Average Score: 95