choose<T> method

List<T> choose<T>({ required List<T> items, int length = 1, bool unique = false, })

Returns a randomly-chosen list of elements from provided items.

length is optional number of elements to return (default is 1).

unique is optional check to return only unique elements (default is false).

Throws ArgumentError if length is not a positive integer or if there are not enough unique elements in items to provide the specified length.

Example:

Choice().choose(items: [1, 2, 3]); // [3]
Choice().choose(items: [1, 2, 3], length: 2); // [3, 1]
Choice().choose(
  items: [1, 2, 3, 2, 1],
  length: 3,
  unique: true
); // [3, 1, 2]

Implementation

List<T> choose<T>({
  required List<T> items,
  int length = 1,
  bool unique = false,
}) {
  if (length <= 0) {
    throw ArgumentError.value(
      length,
      'length',
      'Lenght should be a positive integer',
    );
  }

  if (unique && items.toSet().length < length) {
    throw ArgumentError(
      'There are not enough unique elements to provide the specified length',
    );
  }

  final result = <T>[];
  final random = Random(seed);
  while (result.length < length) {
    final item = items[random.integer(max: items.length - 1)];
    if (!unique || (unique && !result.contains(item))) {
      result.add(item);
    }
  }
  return result;
}