We should add support for GROUP BY. Not entirely sure about the API as you usually want to supply a aggregate function at the same time. Also the return type will be a bit tricky, as the data is a lot more dynamic (and DynamicRealmObject doesn't fit). If we had a Sorted RealmMap it might make sense, although exposing as a List would probably be the more expected.

// Brainstorm ideas
RealmResults<Pair<String, Number>> results = query.groupBy("field", Function.AVERAGE);
RealmMap<String, Number> results = realmresult.groupBy("fieldName", Function.SUM);

http://stackoverflow.com/questions/35533550/is-it-possible-to-use-group-by-concept-in-realm-mobile-database