public static double[][] ConvertToArray <T>(this IGetRatioIntensity func, IEnumerable <T> anns) where T : IAnnotation { var refs = new List <double>(); var samples = new List <double>(); foreach (IAnnotation ann in anns) { refs.Add(func.GetReferenceIntensity(ann)); samples.Add(func.GetSampleIntensity(ann)); } var result = new double[2][]; result[0] = refs.ToArray(); result[1] = samples.ToArray(); return(result); }