How to rank elements when it has duplicates

Siwar Hadj Ali 0
Viewed 40

I am trying to figure out a way to rank items in a list that has duplicated values.

For example:

QTECDE RANK
40 1
30 2
24 3
18 4
4 5
4 5
3 6

But my code always skips a number when I have a duplicated rank. This what I get:

QTECDE RANK
40 1
30 2
24 3
18 4
4 5
4 5
3 7 (7 insted of 6)

Here's my code:

var rankedList = oList.OrderByDescending(p => p.QTECDE)
                      .Select((p, i) => new { Order = 1 + i, lst = p })
                      .GroupBy(p => new { p.lst.QTECDE })
                      .SelectMany(g => g.Select(p => new
                                        {
                                         RANK = g.Min(x => x.Order),
                                         NO_ART = p.lst.NO_ART,
                                         QTECDE = p.lst.QTECDE,
                                         LIB_INDEX_FR_SUP = p.lst.LIB_NIVEAU_SUP_FR,
                                         LIB_IMAGE = p.LIB_IMAGE,
                                        }));

Any solutions?

linq .net c#
2 Answers

You're determining the rank/order on your source items. You want to apply the (item, index) to your SelectMany() instead of your Select().

CodeCaster0

You just need the index of the group not the items:

var rankedList = oList
    .OrderByDescending(p => p.QTECDE)
    .GroupBy(p => new { p.QTECDE })
    .SelectMany((g, groupIndex) => g
        .Select(p => new
        {
            RANK = groupIndex + 1,
            NO_ART = p.NO_ART,
            QTECDE = p.QTECDE,
            LIB_INDEX_FR_SUP = p.LIB_NIVEAU_SUP_FR,
            LIB_IMAGE = p.LIB_IMAGE,
        }));
Tim Schmelter0
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