replace nan values by mean group by date.year, date.month

[wissam1974]

Your code should be something like this:

data_pd.fillna(data_pd.groupby([data_pd.Dateobs.dt.year, df.Dateobs.dt.month]).transform('mean'), inplace=True)

hi Mr first thank you for your reply, i appreciate it
i tried this

result=data_pd.fillna(data_pd.groupby([data_pd.Dateobs.dt.year, data_pd.Dateobs.dt.month]).transform('mean'), inplace=True)
print (result)

and i am getting the following result:

Output:
None

Process finished with exit code 0

still the same problem its not replace null value by mean
is there anything else i should try
thank you