c＃List <tuple <string，string，=“”int =“”>＆gt; group by min max int

Question

我想通过以下元组进行分组：

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));

结果应该在新的元组中看起来像这样：

//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

你能帮我吗？

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));

建议：不要在C＃中使用元组。以往

Answer 2

按匿名类型分组，然后在群组中使用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();