Question

I have a list of objects. E.g. List<coin> where they contain a string(denom) and int(year).
If the list contains:

"Quarter", 1954
"Quarter", 1990
"Penny", 1925  
"Nickel", 1900 
"Nickel", 2000

How can I get a resultant list where it contains the unique values with just the most recent year? E.g.:

"Quarter", 1990
"Penny", 1925
"Nickel", 2000

Answer 1

You can do this by grouping by name, then either ordering and taking the first result, or by using something like MaxBy from MoreLINQ:

var query = coins.GroupBy(x => x.Name)
                 .Select(g => g.MaxBy(x => x.Year));

or

var query = coins.GroupBy(x => x.Name)
                 .Select(g => g.OrderByDescending(x => x.Year).First());