LINQ技巧：如何通过多次调用GroupBy实现分组嵌套

using System;
using System.Linq;

namespace ConsoleApplication1
{
class Program
{
public class Sdata
{
public string gather;
public int shotcount;

}

static void Main(string[] args)
{
var m = new[]{
new Sdata{gather = "100002",shotcount = 28},
new Sdata{gather = "100002", shotcount =44},
new Sdata{gather = "100003", shotcount = 8},
new Sdata{gather = "100003", shotcount = 20},
new Sdata{gather = "100004", shotcount = 55},
new Sdata{gather = "100004", shotcount = 60},
new Sdata{gather = "100005", shotcount = 10},
new Sdata{gather = "100005", shotcount = 60},
new Sdata{gather = "100006", shotcount = 24},
new Sdata{gather = "100006", shotcount = 75},
new Sdata{gather = "100010", shotcount = 41},
new Sdata{gather = "100010", shotcount = 81},
new Sdata{gather = "100012", shotcount = 75},
new Sdata{gather = "100012", shotcount = 100},
};

var q2 =
from s in m
group s by s.gather into gatherGroup
select new
{
gather = gatherGroup.Key,
shotcountGroups =
from s2 in gatherGroup
group s2 by s2.shotcount into shotcountGroups
select new
{
shotcount = shotcountGroups.Key,
//Days =
// from s3 in shotcountGroups
// orderby s3.Day
// select s3.Day
}
};

foreach(var item in q2)
{
Console.WriteLine("1gather={0}",item.gather);
foreach(var itme2 in item.shotcountGroups)
{
Console.WriteLine("\tshotcount = {0}",itme2.shotcount);
}
}

var q = m.GroupBy(
s => s.gather,
(gather, gatherGroup) => new
{
gather,
shotcountGroups =
gatherGroup.GroupBy(
s2 => s2.shotcount,
(shotcount, shotcountGroups) => new
{
shotcount,
//Days = shotcountGroups.OrderBy(s3 => s3.Day).Select(s3 => s3.Day)
}
)
}
);

foreach (var elem in q)
//foreach (var elem in q2)
{
Console.WriteLine("2gather = {0}", elem.gather);
foreach (var elem2 in elem.shotcountGroups)
{
Console.WriteLine("\tshotcount = {0}", elem2.shotcount);
//foreach (var day in elem2.Days)
// Console.WriteLine("\t\tDay = {0}", day);
}

}

Console.Read();
}
}
}