C＃列表<組<字符串，字符串，整數>>組由最小值最大值INT

Question

我想組由下列元組：

List<Tuple<string, string, int>> tu = new List<Tuple<string, string, int>>(); 
tu.Add(new Tuple<string, string, int>("a", "b", 201601)); 
tu.Add(new Tuple<string, string, int>("a", "b", 201602)); 
tu.Add(new Tuple<string, string, int>("a", "b", 201603)); 
tu.Add(new Tuple<string, string, int>("c", "d", 201601)); 
tu.Add(new Tuple<string, string, int>("c", "d", 201602)); 

的結果應該是這樣的一個新的記錄：

//Item1, Item2, Min(Item2), Max(Item3) 
List<Tuple<string, string, int, int>> newtu = new List<Tuple<string, string, int, int>>(); 

a,b,201601,201603 
c,d,201601,201602 

你能幫我嗎？

Answer 1

from t in tu 
group t by new { t.Item1, t.Item2 } into g 
select Tuple.Create(g.Key.Item1, g.Key.Item2, g.Min(t => t.Item3), g.Max(t => t.Item3)); 

建議：不要在C＃中使用元組。曾經

Answer 2

集團由一個匿名類型，然後在組織使用Min + Max：

List<Tuple<string, string, int, int>> newtu = tu 
    .GroupBy(t => new { t1 = t.Item1, t2 = t.Item2 }) 
    .Select(g => Tuple.Create(g.Key.t1, g.Key.t2, g.Min(t => t.Item3), g.Max(t => t.Item3))) 
    .ToList();