C＃LINQ计数元素与DISTINCT

我有一组KeyValuePair项目，其中DateTime为键，字符串为value。 基本上我的数据看起来像：

12/07/2013 - 10220 12/07/2013 - 10220 12/07/2013 - 12220 12/07/2013 - 11240 12/07/2013 - 15220 13/07/2013 - 23220 13/07/2013 - 35620 14/07/2013 - 15620 14/07/2013 - 15620 

我想列出我每天有多少项（不同）。 所以查询会导致：

 12/07/2013 - 4 13/07/2013 - 2 14/07/2013 - 1 

Answer 1

使用group by

 var dateGrouped = dates.GroupBy(x => x.Key) .Select(x => new { Date = x.Key, Values = x.Distinct().Count() }); 

Answer 2

以下是完整示例的解决方案

  var list = new[] { new {Date = new DateTime(2013,07,12), value = 10220}, new {Date = new DateTime(2013,07,12), value = 10220}, new {Date = new DateTime(2013,07,12), value = 12220}, new {Date = new DateTime(2013,07,12), value = 11240}, new {Date = new DateTime(2013,07,12), value = 15220}, new {Date = new DateTime(2013,07,13), value = 23220}, new {Date = new DateTime(2013,07,13), value = 35620}, new {Date = new DateTime(2013,07,14), value = 15620}, new {Date = new DateTime(2013,07,14), value = 15620}, }; var res = from l in list group l by new { l.Date } into g select new { g.Key.Date, value = g.Distinct().Count() }; foreach (var item in res) { Console.WriteLine(item.Date + " " + item.value); }