求一个操作集合的表达式Lambda

[wddjzzxsdz]

一个集合里面有同一类对象若干。
找出一个属性出现次数最多的对象。
比如 里面放的5个user，
u1:age=18,name='123';
u2:age=18,name='234';
u3:age=19,name='222';
u4:age=20,name='224';
u5:age=21,name='222';
找出age属性的值出现最多的对象
就是他俩
u1:age=18,name='123';
u2:age=18,name='234';
考虑可能出现两组的情况
u1:age=18,name='123';
u2:age=18,name='234';
u3:age=19,name='222';
u4:age=20,name='224';
u5:age=20,name='222';

[wang1986614]

友情帮顶！

[q107770540]

var result=(from l in list
           group l by l.age into g
           orderby g.Count() descending
           from t in g
           select new user{
               age=t.age,
               name=t.name
           }).FirstOrDefault();

[机器人]

按照 age 分组，且count最多的数据。

 var users = new List<User>
 {
     new User { age=18, name="1" },
     new User { age=18, name="2" },
     new User { age=19, name="3" },
     new User { age=20, name="4" },
     new User { age=19, name="5" },
     new User { age=21, name="6" },
 };
 var groupByAge = from u in users
                  group u by u.age into g
                  select new { key = g.Key, count = g.Count(), items = g };
 var result = from u in users
              let maxCntAge = groupByAge.Max(g => g.count)
              let ages = groupByAge.Where(g => g.count == maxCntAge).Select(g => g.key)
              where ages.Contains(u.age)
              select u;
 foreach (var u in result)
     Console.WriteLine("{0}:{1}", u.name, u.age);

[阿非]

List<User> userList = new List<User>() { 
    new User{Age=18,Name="123"},
    new User{Age=18,Name="312"},
    new User{Age=19,Name="23"},
    new User{Age=20,Name="234"},
    new User{Age=21,Name="345"},
    new User{Age=22,Name="456"},
    new User{Age=22,Name="345"},
    new User{Age=23,Name="64"}
};

var result = from u in userList
                group u by u.Age into g
                let count = g.Count()                         
                select new
                {
                    g.Key,
                    count
                };
var ttt = from t in result
            where t.count == result.Max(a => a.count)
            select new User { Age = t.Key, Name = userList.First(u => u.Age == t.Key).Name };
foreach (var u in ttt)
{
    Console.WriteLine("Name:{1},Age:{0}", u.Age, u.Name);
}

[笨熊熊]

[Quote=引用 2 楼 q107770540 的回复:]

C# code
var result=(from l in list
group l by l.age into g
orderby g.Count() descending
from t in g
select new user{
age=t.age,
……
[/Quote]

這個好簡練。

[路人乙e]

//得到分组后的结果
var glist = (from item in list
                group item by item.Age into g
                orderby g.Count() descending
                select g);
//得到出现次数最多的age集合
var ages = glist.Where(g => g.Count() == glist.First().Count()).Select(g => g.Key);
//查询age在age集合中的对象
var result = list.Where(p => ages.Contains(p.Age));

[wddjzzxsdz]

好啊 好啊。
果然是高手如云。