How do I order the elements in a group by linq query, and pick the first?

Question

I have a set of data that contains a type, a date, and a value.

I want to group by the type, and for each set of values in each group I want to pick the one with the newest date.

Here is some code that works and gives the correct result, but I want to do it all in one linq query rather than in the iteration. Any ideas how I can achieve the same result as this with purely a linq query...?

var mydata = new List<Item> {
    new Item { Type = "A", Date = DateTime.Parse("2016/08/11"), Value = 1 },
    new Item { Type = "A", Date = DateTime.Parse("2016/08/12"), Value = 2 },
    new Item { Type = "B", Date = DateTime.Parse("2016/08/20"), Value = 3 },
    new Item { Type = "A", Date = DateTime.Parse("2016/08/09"), Value = 4 },
    new Item { Type = "A", Date = DateTime.Parse("2016/08/08"), Value = 5 },
    new Item { Type = "C", Date = DateTime.Parse("2016/08/17"), Value = 6 },
    new Item { Type = "B", Date = DateTime.Parse("2016/08/30"), Value = 7 },
    new Item { Type = "B", Date = DateTime.Parse("2016/08/18"), Value = 8 },
};

var data = mydata.GroupBy(_ => _.Type);

foreach (var thing in data) {

    #region 
            
    // How can I remove this section and make it part of the group by query above... ?          
    var subset = thing.OrderByDescending(_ => _.Date);
    var top = subset.First();
    
    #endregion
    
    Console.WriteLine($"{thing.Key} {top.Date.ToString("yyyy-MM-dd")} {top.Value}");
}

Where Item is defined as:

public class Item {     
    public string Type {get;set;}
    public DateTime Date {get;set;}
    public int Value {get;set;}     
}   
            

Expected output:

A 2016-08-12 2
B 2016-08-30 7
C 2016-08-17 6

Answer 1

Use select to get the FirstOrDefault (or First - because of the grouping you won't get a null) ordered descending:

var data = mydata.GroupBy(item => item.Type)
                 .Select(group => group.OrderByDescending(x => x.Date)
                 .FirstOrDefault())
                 .ToList();

Or SelectMany together with Take(1)

var data = mydata.GroupBy(item => item.Type)
                 .SelectMany(group => group.OrderByDescending(x => x.Date)
                 .Take(1))
                 .ToList();