systematicSample<T> function
Systematic sampling: take every step-th element starting at start.
Implementation
List<T> systematicSample<T>(List<T> list, int step, {int start = 0}) {
if (step < 1) return [];
final List<T> out = [];
for (int i = start; i < list.length; i += step) {
out.add(list[i]);
}
return out;
}