Linq distinct - Count

Question

I am looking to perform a query on an example list of objects

Date     Username  01/01/2011 james 01/01/2011 jamie 01/01/2011 alex 01/01/2011 james 02/01/2011 matt 02/01/2011 jamie 02/01/2011 alex 02/01/2011 james 02/01/2011 james 02/01/2011 lucy 02/01/2011 alex 03/01/2011 james 03/01/2011 bob 03/01/2011 bob 03/01/2011 james 03/01/2011 james 04/01/2011 alex 04/01/2011 alex 04/01/2011 alex 

I want to use linq to query the list of dates with the number of unique user logins.

For example:

01/01/2011 - 3 02/01/2011 - 5 03/01/2011 - 2 04/01/2011 - 1 

I have tried as tested a number of linq statements but none of these are giving me the desired result. The closest I have got is giving me the distinct dates but with a count of all the users.

Any help would be greatly appreciated.

Answer 1

logins   .GroupBy(l => l.Date)   .Select(g => new   {     Date = g.Key,     Count = g.Select(l => l.Login).Distinct().Count()   });