Fill NA with Average

import numpy as np
import pandas as pd
df = pd.read_csv('abc2.csv')
df
student language science maths history
0 kumar 90 56.0 34.0 34
1 kevin 10 NaN 32.0 67
2 sammy 90 23.0 12.0 32
3 janice 20 NaN 90.0 45
4 peter 30 56.0 45.0 65
5 prem 90 45.0 NaN 34
6 carrol 50 90.0 45.0 23 
# We are going to fill mean value on the NAs.
df.fillna(df.mean(), inplace=True)
df
student language science maths history
0 kumar 90 56.0 34.0 34
1 kevin 10 54.0 32.0 67
2 sammy 90 23.0 12.0 32
3 janice 20 54.0 90.0 45
4 peter 30 56.0 45.0 65
5 prem 90 45.0 43.0 34
6 carrol 50 90.0 45.0 23
Note

inplace=True param will change the current object (in this case our dataframe).