How to get the items with lowest value using LINQ?

Question

I have below class -

  public class Test
    {
        public string TestServerName;
        public string TestApplicationRunning;
        public bool IsAvailable;
        public long Counter;
    }

How to get the items with lowest counter value using LINQ?

Suppose lowest counter value is 0 in all items then LINQ should return all items with Counter value 0.There can be more then 1 items with counter value minimum.

Had you tried something before asking, it could've been a better question — Ghasem, Feb 09 '16 at 07:32
Probably duplicate of http://stackoverflow.com/questions/914109/how-to-use-linq-to-select-object-with-minimum-or-maximum-property-value and http://stackoverflow.com/questions/2736236/how-to-use-linq-to-find-the-minimum — xanatos, Feb 09 '16 at 07:36

Farhad Jabiyev · Accepted Answer · 2016-02-09T07:40:23.413

6

You can use Min extension method and then filter source with the help of Where extension method:

var minValue = source.Min(x => x.Counter);
var result = source.Where(x => x.Counter == minValue).ToList();

Don't forget to include Systme.Linq namespace. BTW, with this approach, you will execute two queries to the source.

edited Feb 09 '16 at 07:40

answered Feb 09 '16 at 07:25

Farhad Jabiyev

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Above example is good as total iterations will be `2 x length of source`. Instead of combining these 2 queries and then iterations will be `length of source x length of source` – Nikhil Agrawal Feb 09 '16 at 07:31

score 0 · Answer 2 · answered Feb 09 '16 at 07:33

0

You could also do :

source.GroupBy(x=>x.Counter)
      .OrderBy(x=>x.Key)
      .Take(1)
      .Select(x=>x).ToList();

though it's not as obvious as Fᴀʀhad's solution :)

answered Feb 09 '16 at 07:33

sirrocco

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Bad example. Too Many iterations. – Nikhil Agrawal Feb 09 '16 at 07:34
Did anyone say that they care about iterations ? – sirrocco Feb 09 '16 at 07:35
1

No one said that, but make sure that the code that OP gets is good and more readable. Your code though gets result but is less easily readable and memory consuming also. – Nikhil Agrawal Feb 09 '16 at 07:42
And I made mention that it's a less obvious / readable solution than the one provided by Farhad. Anyhow, I'll leave it here. If anyone wants to delete it, feel free to do so. – sirrocco Feb 09 '16 at 07:43

score 0 · Answer 3 · answered Feb 09 '16 at 07:44

Try this example:

List<Test> lstTests = new lstTests();
Test test1 = new Test();
Test test2 = new Test();
Test test3 = new Test();

test1.Counter = 3;
test2.Counter = 4;
test3.Counter = 3;

lstTests.Add(test1);
lstTests.Add(test2);
lstTests.Add(test3);


var valMin = lstTests.Min(m => m.Counter);
var results = source.Where(x => x.Counter == valMin).ToList();

OR

var result = source.Where(x => x.Counter == valMin).FirstOrDefault();

If u want the first occurance Use FirstOrDefault.

score 0 · Answer 4 · answered Feb 09 '16 at 08:08

With below query you can find nth lowest value

int ix = 1;
var orderedSource  = source.OrderBy(i => i.counter).Select(y => new { rank =ix++ , value = y });

you pass any value instead of N to get nth lowest value

int N = 4;
var  result  = orderedSource.Where(x=>x.rank == N).FirstOrDefault();
Test testValue = result.value;

score 0 · Answer 5 · answered Apr 23 '20 at 08:57

You can use the MinBy (or MaxBy) extension method from MoreLinq.

As from this issue, the min by functionality change to return IEnumerable of T (if to be more precise: IExtremaEnumerable) instead of only one T item to:

public static IExtremaEnumerable<TSource> MinBy<TSource, TKey>(this IEnumerable<TSource> source,
        Func<TSource, TKey> selector, IComparer<TKey> comparer)

Usage Example:

using MoreLinq;

IEnumerable<Test> testList = source.MinBy(p => p.Counter);

How to get the items with lowest value using LINQ?

5 Answers5