seasonality in serie

mrom34 series_seasonal computes the seasonal component across the entire series - the seasonal part is the median of each bin across all periods. Since in the given series it starts with periods below zero and then periods above zero it happens for this specific case that the seasonal component for a period of 24 points is actually zero, you can verify it with the following query:

print s=dynamic(
[-2,-11,7.5,2.5,-4,-2,5,-0.5,1.5,0.5,2.5,-2,-0.5,0.5,0,0,-0.5,0.5,-2,-10.5,-4,-6,-14,-7.5,-15,-1,-7,-5.5,-17,0.5,-4.5,-1.5,2.5,1,0,0,-2,0,-1.5,1,0,0,-11.5,-16.5,-29,-19,-25,-11,-6,-15,-3.5,-8.5,-13,5,-6.5,1,2,2.5,-1,0.5,1.5,0,1,1,-1,-0.5,-3.5,-5.5,-13.5,-7.5,0.5,-17.5,-5,-12,-4,-1.5,-6.5,4.5,1.5,-1.5,-5,-2,-1.5,0.5,1.5,0,-0.5,0,-1.5,3,-8,-15,-5,-11.5,-13,-9,-6,2,0,-15,2,-1.5,0,0,-1,0,0,0,0,1.5,-1,1.5,-1,1,-11.5,-2,-15,-17.5,-10,-18.5,-6.5,-12,-20,-3.5,-11,-3.5,1,0.5,2.5,2,3,0,-0.5,-1,-0.5,-0.5,-0.5,-0.5,-11,-20.5,-7,-13.5,-14,-15.5,-3.5,-16.5,-12,3.5,2.5,17,2.5,0,3,0,0,-1,0,0.5,0,0.5,0.5,-2,0,-14.5,-11.5,-22,-23.5,-10.5,-13,-3,-2.5,-2.5,4,6,2,0.5,0.5,0.5,0.5,2,0.5,1.5,0,0,1.5,-1.5,-5,-3.5,-13,-20,-13,-7.5,-22,-16,-11,-13.5,-10,-0.5,-0.5,1.5,0.5,0,-1,0,0,0,0.5,0,-1,-2,-7.5,-9.5,-20,-20,-16,-16,-19,-11,-7.5,-14.5,6,-5,-0.5,1,-2,0.5,2,-0.5,-0.5,1,0,0,1,-1.5,-2.5,5.5,-0.5,1.5,-4.5,-4.5,-4,-2,4,0.5,1.5,-1.5,-1.5,-0.5,-1,3,-0.5,1.5,-0.5,-1,0.5,2,0.5,-4,3,-7,-10,-3.5,-5,-2,-3,-5,0,-11,-8,2.5,5,0,0,0,1,0,0,-1.5,0,-0.5,1,-1,-9.5,-11,-3,-1.5,-8,-7.5,-11.5,-15,-4,-5.5,-4,-2.5,-1,0.5,-0.5,0,-1,-1,0.5,1,0.5,1.5,0.5,-3.5,0,0.5,-6,-10.5,-7,-5.5,-0.5,1.5,2,-6.5,-7.5,-1,-1.5,1,-2,-2,-4,1,0,0.5,0,-0.5,-1.5,2,0,-2.5,-13.5,-10,-9.5,-9.5,2,3,-12.5,-4.5,-12,2,-2,-2.5,-0.5,-0.5,-0.5,1,0.5,-0.5,0,0,0.5,4.5,15,6.5,4,6,13,7.5,15,1,7,11.5,12,6.5,6.5,8.5,-1.5,-1,2,-1,1,0,0.5,0,0,47,41.5,9.5,34,61,16,35,21,11,21.5,41.5,43,5,4.5,-1,3,-0.5,0,-1.5,0.5,0,0,-1,1,0.5,2.5,-5.5,0.5,-1.5,-0.5,4.5,4,2,-6,-0.5,-1.5,-8.5,0.5,1.5,4,0,0.5,-0.5,-0.5,0,1.5,0,0.5,-3,-3,7,5,3.5,5,2,3,-2,-1,11,-2,-0.5,-1,0,0,4,0,3,0,-0.5,1,0.5,4,-3,10.5,2,3,1.5,8,7.5,6.5,12,4,3.5,4,8.5,-1,-1.5,0.5,0,-1,0,0.5,-1,0.5,-0.5,1.5,1.5,0,-0.5,6,19.5,16,25.5,22.5,-1.5,19,4.5,2.5,0,-2.5,-5,-2,0,2,-1,-1,-0.5,0,3.5,0.5,4,0,3.5,11.5,22,9.5,27.5,23,24,2.5,2.5,9,-2,-4,0.5,-2.5,-0.5,-1.5,-1,-0.5,-0.5,1,1,-3.5,-0.5,2,3.5,18,26,23,29.5,17,21,10,5.5,10,-0.5,0.5,-3.5,-0.5,0,0,0,0,0,-0.5,0,0,0,7.5,9.5,20,19,25,11,6,11,3.5,8.5,-6,-17,0.5,-4,-2,-1.5,0,1.5,-0.5,0,0,0,-1,4.5,18.5,10.5,22.5,20.5,29.5,27.5,19,12,19,11.5,17.5,1.5,-0.5,0.5,1,0,0.5,-0.5,0.5,0,-0.5,-1,-0.5,4,17,9,18,8.5,30,15,15,25,14,23,15,0.5,0,0,1,-2,-2,0,0,0.5,0,-0.5,-1,1,9.5,25,30,24.5,20,22.5,35.5,27,27,16.5,8,2.5,1,-0.5,-2.5,-1,1,0,-1.5,1,-0.5,0.5,-1.5,0.5,9,3.5,19,10.5,7,5.5,0.5,15.5,-2,-3.5,-2.5,0,1.5,0,2,3,0,3,0,-0.5,1,-0.5,-0.5,-2,23,2.5,19.5,10,21.5,9.5])
| mv-expand with_itemindex=idx s to typeof(double)
| project idx, s
| extend bin_idx = idx % 24
| order by s asc 
| summarize s=make_list(s) by bin_idx
| extend seasonal_componenet = (todouble(s[13]) + todouble(s[14]))/2