Given an enumerable of Parent where each entry holds an IEnumerable of Child objects
IEnumerable<KeyValuePair<Parent, IEnumerable<Child>>>
I want to reverse it so it is an IEnumerable of Child where each entry holds an IEnumerable of Parent objects.
IEnumerable<KeyValuePair<Child, IEnumerable<Parent>>>
source
.SelectMany(
x => x.Value,
(k, v) => new
{
Child = k.v,
Parent = k.Key
})
.GroupBy(
keySelector: x => x.Child,
elementSelector: x => x.Parent)
.ToDictionary(
keySelector: x => x.Key,
elementSelector: x => x.AsEnumerable());