如何分组项目列表 <keyvaluepair <string,datetime[]> &gt;过期

Question

I have a datatable filled by date , day ,name and type so I read from this datatable into List> using C#.net so the code is this :

 dicArray = dtrd.AsEnumerable()
    .Select(Row => Row["IDp"]).Distinct()
    .Select(Id => new KeyValuePair<string, string[]>(
        Id.ToString(),
        dtrd.AsEnumerable()
            .Where(Row => Row["IDp"].ToString() == Id.ToString())
            .Select(Row => Row["date"].ToString()+";"+ Row["day"].ToString()+";"+Row["nobatkari"].ToString() + ";" + Row["pname"].ToString())
            .ToArray()))
    .ToList();

now I want to count each item over date I mean that I want to know how many rows are with the same date please help me to solve it

for example:

1   **2017-02-19** 15:12:20 1   0   1   0
1   **2017-02-19** 15:12:37 1   0   1   0
1   **2017-02-19** 15:12:41 1   0   1   0  Count:3
1   **2017-02-20** 15:14:10 1   2   1   0
1   **2017-02-20** 16:38:14 1   2   1   0
3   **2017-02-20** 16:38:19 1   2   1   0   Count:3
3   **2017-02-21** 16:39:09 1   0   1   0
3   **2017-02-21** 17:25:06 1   0   1   0
2   **2017-02-21** 18:28:50 1   0   1   0   Count:3
2   **2017-02-22** 18:29:04 1   0   1   0   Count:1
2   **2017-02-23** 18:29:17 1   0   1   0
3   **2017-02-23** 18:30:45 1   0   1   0   Count:2
2   **2017-02-24** 18:31:32 1   0   1   0
2   **2017-02-24** 18:31:47 1   0   1   0   Count:2
2   **2017-02-25** 18:32:18 1   4   1   0   Count:1

Of course I want date section not time include

Answer 1

var res = yourList.GroupBy(x => x.date.Date).Select(x=> new { date = x.Key, count = x.Count() });

这将创建一个包含日期和每个日期的元素计数的新列表。