batch method

Iterable<Iterable<T>> batch(int size, { bool includeTail = false, })

Groups elements in the iterator into batches of size length, optionally truncating elements that don't fit into a full-size batch.

Iterates through the iterator and groups elements into a secondary list of size length. Once the list is full, the list is then yielded.

If includeTail is false, when the source iteration is complete, any remaining elements are discarded. If true, these elements are returned as a final list of some length less than size. (False by default.)

Example:

void main() {
  final list = [1, 2, 3, 4, 5, 6];
  final result = list.batch(2);

  // Result: [[1, 2], [3, 4], [5, 6]]
}

Implementation

Iterable<Iterable<T>> batch(int size, {bool includeTail = false}) sync* {
  if (size <= 0) {
    throw ArgumentError('The value of "size" must be greater than zero');
  }

  var package = <T>[];

  for (var v in this) {
    package.add(v);
    if (package.length >= size) {
      yield package;
      package = <T>[];
    }
  }

  if (package.isNotEmpty && includeTail) {
    yield package;
  }
}