使用linq列出<int>过滤

Question

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

这非常简单Enumerable.GroupBy:

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的时候.)

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() });

或者使用替代语法:

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