groupBy<K> method

Map<K, List<T>> groupBy<K>(
  1. K keySelector(
    1. T
    )
)

Groups elements by a key.

Implementation

Map<K, List<T>> groupBy<K>(K Function(T) keySelector) {
  final map = <K, List<T>>{};
  for (var element in this) {
    (map[keySelector(element)] ??= []).add(element);
  }
  return map;
}