leastOccurrences method

(double, int)? leastOccurrences()

Finds the least common value in the list.

Returns a record (tuple) containing the least common value and its frequency. If the list is empty, returns null.

Implementation

(double, int)? leastOccurrences() {
  if (isEmpty) {
    return null;
  }

  // Create a new HashMap to store each double and its frequency.
  final HashMap<double, int> frequencyMap = HashMap<double, int>();

  // Iterate over each double in the list.
  for (final double item in this) {
    // Update the frequency of the current double in the map,
    // or set it to 1 if it's not in the map yet.
    frequencyMap.update(item, (int value) => value + 1, ifAbsent: () => 1);
  }

  // Find and return the key with the highest value (frequency) in the map.
  final MapEntry<double, int>? leastCommonEntry = frequencyMap.entries.fold(
    null,
    (MapEntry<double, int>? previous, MapEntry<double, int> element) =>
        previous == null || element.value < previous.value ? element : previous,
  );

  if (leastCommonEntry == null) {
    return null;
  }

  // Return a tuple with the least common value and its frequency.
  return (leastCommonEntry.key, leastCommonEntry.value);
}