Write a Python program to fill an intermittent time series so all missing dates show up with values of previous non-missing date

Solution

import pandas as pd
import numpy as np
ser = pd.Series([1,10,3, np.nan], index=pd.to_datetime(['2000-01-01', '2000-01-03', '2000-01-06', '2000-01-08']))
print(ser.resample('D').ffill())