C# 基于键c将两个列表合并到

我有班级奖励，每次游戏我都会保留用户的钱。 我有两张单子，不知怎的，我需要列举出来。我在下面写下示例列表和期望的结果

public class Reward
{
    public int Game { get; set; }
    public int User { get; set; }
    public int Money { get; set; }

    public Reward Merge(Reward p)
    {
       return new Reward { Game = this.Game, User = this.User, Money = this.Money + p.Money};
    }
}

    IList<Reward> list1 = new List<Reward>();
    list1.Add(new Reward {Game = 1, User = 1, Money = 10});
    list1.Add(new Reward { Game = 1, User = 2, Money = 20 });
    list1.Add(new Reward { Game = 1, User = 3, Money = 30 });


    IList<Reward> list2 = new List<Reward>();
    list2.Add(new Reward { Game = 2, User = 1, Money = 15 });
    list2.Add(new Reward { Game = 2, User = 2, Money = 25 });
    list2.Add(new Reward { Game = 2, User = 4, Money = 35 });

我试着

IList<Reward> listConcat = list1.Concat(list2)
                .GroupBy(u=> u.User)
                .Select(???)
                .ToList();

---

但是怎么做呢？

请更改行：

 return new Reward { Game = this.Game, User = this.User, Money = this.Money + p.User

到

---

您使用GroupBy的方法是正确的，这应该可以完成以下工作：

IEnumerable<Reward> result =
    from r in list1.Concat(list2)
    group r by r.User into groupedRewards
    select new Reward
    {
        Game = 0,   //what game to use?
        User = groupedRewards.Key,
        Money = groupedRewards.Sum(r => r.Money)
    };

编辑：与lambda表达式相同：

IEnumerable<Reward> result = list1.Concat(list2)
    .GroupBy(u => u.User)
    .Select(g => new Reward
    {
        Game = 0,  //what game to use?
        User = g.Key,
        Money = g.Sum(r => r.Money)
    });

---

这不是很漂亮，但很管用

var listConcat = list1.Concat(list2)
                .GroupBy(u=> u.User)
                .Select(rewards => new Reward { 
                                                User = rewards.Key, 
                                                Money = rewards.Select(reward => reward.Money).Sum() 
                                              }
                       )
                .ToList();

使用.GroupBy，您可以得到一个iGroup列表，因此选择如下：

IEnumerable<Reward> listConcat = list1.Concat(list2)
                                .GroupBy(x => x.User)
                                .Select(x => new Reward { User= x.Key, Money=x.Sum(y => y.Money) });

---

我想象一个接近你所寻找的答案是这样的：

var catList = list1.Concat(list2)
                   .GroupBy (x => x.User)
                   .Select (y => new Reward{Game = 0, Money = y.Sum (z => z.Money), 
                                User =  y.Key})
                   .ToList();

至于使用哪种游戏，你可以考虑匿名选择，即

.Select(new {Money = y.Sum (z => z.Money), User =  y.Key})

这将为您提供一个匿名类型，其中包含您希望使用的信息。然而，如果你想把它从方法中传递出去，最好的做法是给它一个类型，或者只是理解游戏0是你所有游戏的超集

IList<Reward> listConcat = list1.Concat(list2)
                .GroupBy(person => person.User)
                .Select(group => group.Aggregate((rewardone, rewardtwo) => rewardone.Merge(rewardtwo)))
                .ToList();

.Select(new {Money = y.Sum (z => z.Money), User =  y.Key})

IList<Reward> listConcat = list1.Concat(list2)
                .GroupBy(person => person.User)
                .Select(group => group.Aggregate((rewardone, rewardtwo) => rewardone.Merge(rewardtwo)))
                .ToList();