LINQ:按列表<String>中的唯一项目排序

Question

我有一个正确存储在List <>中的ID列表.我现在需要对此列表进行分组,并获取按降序排序的出现次数的计数.

例:

List<string> aryIDs = new List<string>;
aryIDs.Add("1234");
aryIDs.Add("4321");
aryIDs.Add("3214");
aryIDs.Add("1234");
aryIDs.Add("4321");
aryIDs.Add("1234");

会产生:

"1234", 3
"4321", 2
"3214", 1

这在TSQL中很容易,但我想避免服务器往返,不必要的表等,如果可能的话.

提前致谢.

更新:Ralph Shillington的VB.NET转换如下:

Dim result = From id In aryIDs _
                     Group id By id Into Group _
                     Order By Group.Count() Descending _
                     Select id, Count = Group.Count()

result.Dump()

Answer 1

List<string> aryIDs = new List<string>();
aryIDs.Add("1234");
aryIDs.Add("4321");
aryIDs.Add("3214");
aryIDs.Add("1234");
aryIDs.Add("4321");
aryIDs.Add("1234"); 

var result =     from id in aryIDs
group id by id into g
orderby g.Count() descending
select new { Id=g.Key, Count=g.Count() };

result.Dump();

将其剪切并粘贴到LinqPad中,你应该很高兴.

它也可以使用Lambda表达式编写为:

aryIDs.GroupBy (id => id).OrderByDescending (id => id.Count()).Select(g => new { Id=g.Key, Count=g.Count()}).Dump();