C# LINQ return counter array indices max to min

Question

A newbie with C# and LINQ. I have an array which is essentially a counted sequence.

{1,3,5,2,7,2}

I am trying to write a query that returns list of indices with highest values in descending order:

4,2,1,3,5,0

I can get the maximum index with this query below, but I can't seem to work out how to get the next indexes in sequence with a single query.

int index = array.ToList().IndexOf(array.Max());

possible duplicate of [Linq Orderby Descending Query](http://stackoverflow.com/questions/5344805/linq-orderby-descending-query) — Old Fox, Aug 31 '15 at 07:13

score 10 · Accepted Answer · answered Aug 31 '15 at 07:11

10

This works:

var list = new [] {1,3,5,2,7,2};

var indices =
    list
        .Select((n, i) => new { n, i })
        .OrderByDescending(x => x.n)
        .Select(x => x.i)
        .ToArray();

answered Aug 31 '15 at 07:11

Enigmativity

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Thanks, Enigmativity! – tarzan Aug 31 '15 at 08:53
@tarzan - If you like my answer don't forget to click the accept tick. :-) – Enigmativity Aug 31 '15 at 10:20

score 5 · Answer 2 · answered Aug 31 '15 at 07:11

5

You can use Select:-

var result = numbers.Select((v, i) => new { Value = v, Index = i })
                                .OrderByDescending(x => x.Value)
                                .Select(x => x.Index).ToArray();

Working Fiddle.

answered Aug 31 '15 at 07:11

Rahul Singh

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C# LINQ return counter array indices max to min

2 Answers2