Combining array of arrays into single, distinct array using LINQ

Question

Can this be rewritten any better using LINQ? I'm a C#er trying to think in VB.NET for this current project. It's in an ASP.NET Web Forms .vb codebehind:

Public ReadOnly Property AllowedCategoryIds As Integer()
    Get
        Dim ids = New List(Of Integer)

        For Each group In UserData.Current.AdGroups
            'group.CategoryIDs is Integer() type
            ids.AddRange(group.CategoryIDs)
        Next

        Return ids.Distinct()
    End Get
End Property

Answer 1

You can use SelectMany to flatten such a collection.

var array = arrayOfArrays.SelectMany(item => item).Distinct().ToArray(); // C#
Dim array = arrayOfArrays.SelectMany(Function(item) item).Distinct().ToArray() // VB