CODEWITHSUNDEEP
c#linq
user584018
user584018

Reputation: 11304

How to obtain the maximum datetime of each item2 & item3 combination?

I have data from external system in a tuple like this, have lots of item2 and item 3 combinations with different datetime.

var data = new List<Tuple<DateTime, string, string>>
{
    new Tuple<DateTime, string, string>(new DateTime(2021, 04, 01, 5, 10, 20), "A1", "X1"),
    new Tuple<DateTime, string, string>(new DateTime(2021, 04, 01, 6, 10, 22), "A1", "X1"),
    new Tuple<DateTime, string, string>(new DateTime(2021, 04, 02, 7, 11, 21), "A2", "X2")
};

Now I need to fetch MAX datetime against each unique item2 & item3 combinations and return result should be this,

var result = new List<Tuple<DateTime, string, string>>
{
    new Tuple<DateTime, string, string>(new DateTime(2021, 04, 01, 6, 10, 22), "A1", "X1"),
    new Tuple<DateTime, string, string>(new DateTime(2021, 04, 02, 7, 11, 21), "A2", "X2")
};

I am able to fetch MAX datetime for each item2 and item3 combinations where I am passing these values as hard code,

 var maxTimestamp = data.Where(t => t.Item2 == "A1" && t.Item3 == "X1").Max(t => t.Item1);

but I need to iterate each item2 and item3 combinations, how to do this?

Upvotes: 0

Views: 33

Answers (1)

SomeBody
SomeBody

Reputation: 8743

Use GroupBy:

var maxTimestamps = data.GroupBy(x => new { x.Item2, x.Item3}).
                         Select(x => x.OrderByDescending(y => y.Item1).First());

You will get groups with the same Item2 and Item3. Sort these groups by their date and pick the first date of each group.

Upvotes: 1

Related Questions