c# - 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()
  });