df.fillna(0, inplace=True)
df.fillna(df.mean(), inplace=True)
sub2['income'].fillna((sub2['income'].mean()), inplace=True)
In [12]: df[1].fillna(0, inplace=True)
Out[12]:
0 0.000000
1 0.570994
2 0.000000
3 -0.229738
4 0.000000
Name: 1
In [13]: df
Out[13]:
0 1
0 NaN 0.000000
1 -0.494375 0.570994
2 NaN 0.000000
3 1.876360 -0.229738
4 NaN 0.000000
df.reindex(list(range(df.index.min(),df.index.max()+1)),fill_value=0)