averageEx method

num averageEx(
  1. num selector(
    1. T item
    ), {
  2. num resultIfEmpty = 0,
})

calculates the average of a list based on a selector returns 0 if empty

Implementation

num averageEx(
  num selector(T item), {
  num resultIfEmpty = 0,
}) {
  if (length == 0) return resultIfEmpty;
  return this.sumEx(selector) / length;
}