c# - 通过对多行求和来排序列表

Question

我有这样的类(class):

public class UserDataPoint
{
    public string User { get; set; }
    public string Category { get; set; }
    public int Spend { get; set; }

    public UserDataPoint(string strUser, string strCategory, int intSpend)
    {
        User = strUser;
        Category = strCategory;
        Spend = intSpend;
    }
}

其中填充了这样的数据:

var myList = new List<UserDataPoint>() { 
    new UserDataPoint("Bob", "Local", 34),
    new UserDataPoint("Bob", "National", 16),
    new UserDataPoint("Bob", "Mobile", 7),
    new UserDataPoint("John", "Local", 18),
    new UserDataPoint("Fred", "National", 22),
    new UserDataPoint("Fred", "International", 65) };

我想填充一个数组:

UserDataPoint[] myArray;

使用来自 myList 的数据，但按“用户”排序，总计“支出”最高。因此，从上面的示例数据来看，Fred 将在列表中排在第一位 (22 + 65 = 87)，其次是 Bob (34 + 16 + 7 = 57)，最后是 John (18)。

因此我的结果数组将按以下顺序填充:

UserDataPoint[] myArray = new UserDataPoint[] { 
    new UserDataPoint("Fred", "National", 22),
    new UserDataPoint("Fred", "International", 65),
    new UserDataPoint("Bob", "Local", 34),
    new UserDataPoint("Bob", "National", 16),
    new UserDataPoint("Bob", "Mobile", 7),        
    new UserDataPoint("John", "Local", 18) };

如何实现 LINQ 语句来对 myList 执行此排序以给我 myArray？

非常感谢任何可以提供帮助的人。

Answer 1

UserDataPoint[] myArray =
    myList.GroupBy(udp => udp.User)
            .OrderByDescending(g => g.Sum(udp => udp.Spend))
            .SelectMany(g => g)
            .ToArray();