Linq to Objects: does GroupBy preserve order of elements?
Does Enumerable.GroupBy from LINQ to Objects preserve order of elements in the groups?
Found answer on MSDN: Yes.
The
IGrouping<TKey, TElement>objects are yielded in an order based on the order of the elements in source that produced the first key of eachIGrouping<TKey, TElement>. Elements in a grouping are yielded in the order they appear in source.