c# - 使用 linq 在列上运行计数

Question

我有一个看起来像这样的游戏 table : 日期、团队 1、团队 2、在家

样本条目可能是

2010 年 10 月 10 日，A 队、B 队、B 队 - 意味着 B 队在这场比赛中主场作战。有很多球队互相比赛。

我想使用 linq 来获取以下信息:

列出球队在主场的所有比赛，以及最近 3 到 5 场主场比赛。

关于如何实现这一点有什么建议吗？

Answer 1

我制作了一个小示例应用程序。我不是 100% 确定这是否符合您要查找的内容，所以如果我错过了您的问题要点，请发表评论。

编辑 我对其进行了修改以将日期考虑在内。

var games = new[]
{
    new Game() {Date = new DateTime(2010, 12, 1), TeamA = "A", TeamB="B", AtHome = "B"},
    new Game() {Date = new DateTime(2010, 11, 1), TeamA = "A", TeamB="B", AtHome = "A"},
    new Game() {Date = new DateTime(2010, 10, 1), TeamA = "A", TeamB="B", AtHome = "B"},
    new Game() {Date = new DateTime(2010, 9, 1), TeamA = "A", TeamB="B", AtHome = "A"},
    new Game() {Date = new DateTime(2010, 8, 1), TeamA = "A", TeamB="B", AtHome = "B"},
    new Game() {Date = new DateTime(2010, 7, 1), TeamA = "A", TeamB="C", AtHome = "A"},
    new Game() {Date = new DateTime(2010, 6, 1), TeamA = "B", TeamB="C", AtHome = "C"},
    new Game() {Date = new DateTime(2010, 5, 1), TeamA = "B", TeamB="C", AtHome = "C"},
    new Game() {Date = new DateTime(2010, 4, 1), TeamA = "D", TeamB="C", AtHome = "C"},
    new Game() {Date = new DateTime(2010, 3, 1), TeamA = "D", TeamB="B", AtHome = "D"},
    new Game() {Date = new DateTime(2010, 2, 1), TeamA = "D", TeamB="B", AtHome = "B"},
    new Game() {Date = new DateTime(2010, 1, 1), TeamA = "A", TeamB="D", AtHome = "D"},
    new Game() {Date = new DateTime(2009, 12, 1), TeamA = "A", TeamB="D", AtHome = "A"},
    new Game() {Date = new DateTime(2009, 11, 1), TeamA = "A", TeamB="B", AtHome = "A"},
    new Game() {Date = new DateTime(2009, 10, 1), TeamA = "A", TeamB="B", AtHome = "B"}
};

var result = from g in games
             orderby g.Date descending
             where games.Where(w => (w.TeamA == g.AtHome || w.TeamB == g.AtHome) 
                                    && w.Date <= g.Date)
                        .Take(5)
                        .Count(c => c.AtHome == g.AtHome) >= 3
             select g;


class Game
{
    public DateTime Date { get; set; }
    public string TeamA { get; set; }
    public string TeamB { get; set; }
    public string AtHome { get; set; }
}

返回:

12/1/2010 A B B
11/1/2010 A B A
9/1/2010 A B A
7/1/2010 A C A
6/1/2010 B C C