groupBy

Description:

public static HashMap<K,ArrayList<T>> groupBy<T,K> (ArrayList<T> list, owned MapFunc<T,K> keyFn, HashFunc<K> hash_func, EqualFunc<K> equal_func)

Groups list elements by computed keys.

list	source list.
keyFn	key extraction function.
hash_func	hash function for key type K.
equal_func	equality function for key type K.

map of key to grouped elements.