Is this suitable for Linq GroupBy? [duplicate]

This question already has answers here: LINQ implementation of Cartesian Product with pruning (3 answers) Closed 2 years ago.

I have a Dictionary :

      Dictionary<Project,List<User>> dictionary,

every Project has a group of Users.

I want to retrieve organize this data such that all the projects with similar users are arranged into this kind of data structure :

      List<Tuple<List<Project>,List<User>>>

I don't even know where to start. I've been fight开发者_如何学Pythoning with this for days.

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The lists of users are the key by which you should group. In the GroupBy() you could use a comparer like this one:

public class ListComparer<T> : IEqualityComparer<List<T>>
    where T : IComparable<T>
{
    public bool Equals(List<T> x, List<T> y)
    {
        return x.OrderBy(u => u).SequenceEqual(y.OrderBy(u => u));
    }

    public int GetHashCode(List<T> obj)
    {
        return obj.GetHashCode();
    }
}

BTW: The comparer is on Lists and not on IEnumerables, otherwise for each comparison the compared objects should be enumerated over and over.

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Your best best would be to flatten the contents of dictionary and query against that.