使用linq列出过滤

我有一个List对象，其中包含Id值，例如它包含：1,2,10,1,23,11,1,4,2,2，…等我需要找出多少次“1”，“在C＃中使用Linq发生了2“，…等

善意的帮助。

Answer 1

使用Enumerable.GroupBy非常简单：

 var grouped = list.GroupBy(x => x); foreach (var group in grouped) { Console.WriteLine("{0} appears {1} times", group.Key, group.Count()); } 

或者：

 var query = list.GroupBy(x => x, (x, g) => new { Key = x, Count = g.Count() })); foreach (var result in query) { Console.WriteLine("{0} appears {1} times", result.Key, result.Count); } 

（区别在于我们真正将组转换为结果。）

Answer 2

使用GroupBy ：

 var les = new[] { 1, 2, 10, 1, 23, 11, 1, 4, 2, 2 }; var result = les .GroupBy(i => i, (e, g) => new { Value = e, Count = g.Count() }); 

或使用替代语法：

 var result = from i in les group i by i into g select new { Value = g.Key, Count = g.Count() }; 

Answer 3

  var l = new List {1,2,10,1,23,11,1,4,2,2}; l.GroupBy(i => i) .ToList() .ForEach(g => Console.WriteLine("{0} : {1}", g.Key, g.Count())); 

Answer 4

 var list = new List { 1, 2, 10, 1, 23, 11, 1, 4, 2, 2, }; var groups = list.GroupBy(i => i); foreach (var group in groups) Console.WriteLine("{0} occurs {1} times", group.Key, group.Count());