I have a collection of KeyValuePair items with DateTime as key and a string as value. Basically my data looks like:
12/07/2013 - 10220
12/07/2013 - 10220
12/
Below is the solution with complete example
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);
}