Weighted shuffle in Dart

weighted_shuffle.dart

import 'dart:math' show Random, pow;

List<T> weightedShuffle<T>(List<T> items, List<num> weights, [Random rng]) {
  // See https://softwareengineering.stackexchange.com/questions/233541/how-to-implement-a-weighted-shuffle
  // and http://utopia.duth.gr/~pefraimi/research/data/2007EncOfAlg.pdf
  assert(items.length == weights.length);
  if (rng == null) rng = Random();
  final List<double> values = weights
      .map<double>((weight) => -pow(rng.nextDouble(), 1 / weight))
      .toList(growable: false);
  final List<int> order = Iterable<int>.generate(items.length)
      .toList(growable: false)
        ..sort((a, b) => values[a].compareTo(values[b]));
  return [for (int i in order) items[i]];
}