groupBy<K> method

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

Implementation

Map<K, List<T>> groupBy<K>(
  K Function(T item) keySelector,
) {
  final result = <K, List<T>>{};

  for (final item in this) {
    final key = keySelector(item);
    (result[key] ??= <T>[]).add(item);
  }

  return result;
}