Question

I would like a third column “items” with the values that are grouped.

var dic = new Dictionary<string, int>();
dic.Add("a", 1);
dic.Add("b", 1);
dic.Add("c", 2);
dic.Add("d", 3);

var dCounts =
    (from i in dic
    group i by i.Value into g
    select new { g.Key, count = g.Count()});

    var a = dCounts.Where(c => c.count>1 );

dCounts.Dump();
a.Dump();

This code results in:

Key Count
1   2
2   1
3   1

I would like these results:

Key Count Items
1   2     a, b
2   1     c
3   1     d

Answer 1

    var dCounts =
        (from i in dic
            group i by i.Value into g
            select new { g.Key, count = g.Count(), Items = string.Join(",", g.Select(kvp => kvp.Key)) });

Use string.Join(",", {array}), passing in your array of keys.