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 result开发者_运维问答ant list where it contains the unique values with just the most recent year? E.g.:
"Quarter", 1990
"Penny", 1925
"Nickel", 2000
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());
You can do this using group by
like:
var query = from coin in myList
group coin by coin.Name into grouped
select new
{
Name = grouped.Key
Year = grouped.Max(x => x.Year)
};
For another sample like this, check out "max - grouped" in the 101 Linq examples: http://msdn.microsoft.com/en-us/vcsharp/aa336747#maxGrouped
var coins = new Coin[] { ... };
var recentCoins =
from coin in coins
group coin by coin.Denom into g
select new
{
Denom = g.Key,
MostRecentYear = g.Max(c => c.Year)
};
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