C# Linq groupby method syntax

Question

I have the following code

 var myList = new List<int>() {10, 10, 10, 9, 15};

 var groupedMyList = myList.GroupBy(i => i).ToList();

 var hasFourOfSameValue = groupedMyList.Select(g => g.Count() == 4).Any();

The issue is that hasFour comes back as true. I expect it to be false as there is maximum three ints with the same value in the list? (I suspect I go wrong in the groupby call but I can't figure out how to change it).

Question preamble: I want to use LINQ method syntax not LINQ query syntax.

Answer 1

You want:

var hasFourOfSameValue = groupedMyList.Any(grp => grp.Count() == 4);

Any() returns true if the input sequence contains any elements.

Answer 2

The expression groupedMyList.Select(g => g.Count() == 4) returns { false, false, false } . And calling any on a non-empty sequence is true. You want:

var hasFourOfSameValue = groupedMyList.Any(g => g.Count() == 4);