在LINQ中跨多列计数

var data = new List<Person>
{
    new Person { Name = "Alice", Age = 25, Gender = "Female" },
    new Person { Name = "Bob", Age = 30, Gender = "Male" },
    new Person { Name = "Charlie", Age = 25, Gender = "Male" },
    new Person { Name = "David", Age = 35, Gender = "Male" },
    new Person { Name = "Eve", Age = 25, Gender = "Female" }
};

var count = data
    .GroupBy(p => new { p.Age, p.Gender }) // 按照年龄和性别进行分组
    .Select(g => new { g.Key, Count = g.Count() }) // 统计每个分组的记录数量
    .ToList();

foreach (var item in count)
{
    Console.WriteLine($"Age: {item.Key.Age}, Gender: {item.Key.Gender}, Count: {item.Count}");
}

Age: 25, Gender: Female, Count: 2
Age: 30, Gender: Male, Count: 1
Age: 25, Gender: Male, Count: 1
Age: 35, Gender: Male, Count: 1