Somewhat Dynamic Pivot in C#

I started working on a dynamic pivot to be used in Kendo UI, where the user could select the datapoints to be shown in the graph. Didn't quite finish, but here is some of the code, didn't want to waste/lose it; since, the concept was interesting.

Code:

public class StageDataPoints
    {
        public List<StageDataPoint> dataSeries { get; set; }

        public List<ExpandoObject> pivot()
        {
            var datapoints = dataSeries.Select(n => n.DataPoint).Distinct().ToList();

            var sdpGroup = from d in dataSeries
                           group d by new { d.DateTimeGrainValue, d.Stage, d.SubStage }
                               into grp
                               select new
                               {
                                   Key = grp.Key,
                                   Dict = grp.ToDictionary(n => n.DataPoint, n => n.DecimalValueAvg)
                               };

            List<ExpandoObject> defactoObjs = new List<ExpandoObject>();

            foreach (var row in sdpGroup)
            {
                dynamic r = new ExpandoObject();
                r.DateTime = row.Key.DateTimeGrainValue.ToString("M/d/yy h:mm");
                r.Stage = row.Key.Stage;
                r.SubStage = row.Key.SubStage;

                double value = double.NaN;
                string tempDP = "";

                foreach (var dp in datapoints)
                {
                    tempDP = dp;

                    foreach (var idp in row.Dict)
                    {
                        if (idp.Key == dp)
                        {
                            value = idp.Value;
                            break;
                        }
                    }
                    //Console.Write(dp + " " + value.ToString());
                    ((IDictionary<string, object>)r).Add(dp, value);
                }
                defactoObjs.Add(r);
            }
            return defactoObjs;
        }

        public List<StageDataPointMinify> rpt()
        {
            List<StageDataPointMinify> ret = new List<StageDataPointMinify>();
            foreach (var x in dataSeries)
            {
                ret.Add(new StageDataPointMinify()
                {
                    //Convert datetime to javascript verion
                    DateTimeGrainValueStr = x.DateTimeGrainValue.ToString("M/d/yy H:mm"),
                    DateTimeGrainValue = x.DateTimeGrainValue,
                    DataPoint = x.DataPoint,
                    DecimalValueAvg = x.DecimalValueAvg
                });
            }
            return ret;
        }
    }

    public class StageDataPoint
    {
        //public DateTime CalendarGrainValue { get; set; }
        //public string ClockGrainValue { get; set; }
        public DateTime DateTimeGrainValue { get; set; }
        public string Stage { get; set; }
        public string SubStage { get; set; }
        public string DataPoint { get; set; }
        //public Guid CJobGuid { get; set; }
        public string JobName { get; set; }
        public double DecimalValueAvg { get; set; }
        //public double DecimalValueMin { get; set; }
        //public double DecimalValueMax { get; set; }
    }