static double[] Rank(IEnumerable <double> series)
{
if (series == null)
{
return(new double[0]);
}
// WARNING: do not try to cast series to an array and use it directly,
// as we need to sort it (inplace operation)
var data = series.ToArray();
return(ArrayStatistics.RanksInplace(data, RankDefinition.Average));
}