CODEWITHSUNDEEP
c#linq
mameesh
mameesh

Reputation: 3761

Linq find min value of each object

I have a list of objects with the following properties

public class Client
{
Id Guid,
FromDate datetime
}

List of Clients

  List<Clients> clients = new List<Clients>();

There are many of the same Ids in this list with different FromDates. How can I get a list of the Id and the min FromDate for each Id?

So for example:

Id    FromDate
1       2015-01-01
1       2016-01-01
2       2015-02-02
2       2015-12-31

I want to end up with a list with the following:

Id    FromDate
1       2015-01-01
2       2015-02-02

Upvotes: 0

Views: 132

Answers (3)

Timothy Stepanski
Timothy Stepanski

Reputation: 1196

Clients.GroupBy(client => client.Id, client => client)
                .Select(times => times.OrderBy(client => client.FromDate).First())

Upvotes: 0

wake-0
wake-0

Reputation: 3968

There are many different ways two of them are

  • Distinct You have to implement your own IEqualityComparer<Client> (https://msdn.microsoft.com/en-us/library/bb338049.aspx) and than you can call:

    IEnumerable<Client> noduplicates = products.Distinct(new ClientComparer());

  • GroupBy

    var result = clients
                .GroupBy(c => c.Id)
                .Select(g => new { Id = g.Key, FromDate = g.Min(c => c.FromDate) });

var result = from c in clients
    group c by new { id = c.Id } into g
    select new { id = g.Key, FromDate = g.Min(c => c.FromDate) };

Upvotes: 0

ocuenca
ocuenca

Reputation: 39326

You can apply a group by:

var query=clients.GroupBy(c=>c.Id)
                 .Select(g=>new {Id=g.Key, FromDate=g.Min(c=>c.FromDate)});

Upvotes: 4

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