In EXCEL, calculating a geomean of size 2 on Col1, would result in a 6 in row 1 of Geo_2 as the geomean of 4 and 9 is 6. In Pandas or numpy it appears to be the reverse, with a min_period = 1, the first row reflects the calculation of just 1 value and the subsequent calculations use the previous and current row of Col1 to calculate the geomean. I want the caluclation window to be the current and the next row of col1, so that the first value of Geo_2 is 6 and the last value should be 2.
DASeries = [4,9,3,3,5,7,8,4,2]
import numpy as np
import pandas as pd
from scipy.stats.mstats import gmean
DA_df = pd.DataFrame(DASeries)
geoMA2 = [2,3]
geo_df = pd.DataFrame([pd.Series(DASeries).rolling(window =elem, min_periods = 1).apply(gmean, raw =True) for elem in geoMA2]).T
Final = pd.concat([DA_df,geo_df],axis=1)
labs = ['Col1','Geo_2','Geo_3']
Final.columns = labs
Final
Using .iloc[::-1]
pd.Series(DASeries).iloc[::-1].rolling(window =2, min_periods = 1).apply(gmean).iloc[::-1]
0 6.000000
1 5.196152
2 3.000000
3 3.872983
4 5.916080
5 7.483315
6 5.656854
7 2.828427
8 2.000000
dtype: float64