Solved by liujie_zhang in post #4 
              
              
                OK, I almost understand your data frame. 
I want to ensure that for each data [x1,x2, …, x460]，the front of 20 features [x1, …, x20] is associated with a timestamp(like Date0)，and [x21,…, x40] is associated with Date1… MeanWhile, I suppose that Date0 < Date1 < … < Date22，which means Date0 is earlier…