pandas fillna not working

Question

I have a dataframe with nans in it:

>>>df.head() Out[1]:              JPM US SMALLER COMPANIES C ACC 1990-01-02                             NaN 1990-01-03                             NaN 1990-01-04                             NaN 1990-01-05                             NaN 1990-01-08                             NaN 

I have another dataframe with values in it:

>>>t.head() Out[1]:  1990-01-02    51.95 1990-01-03    52.63 1990-01-04    53.04 1990-01-05    52.07 1990-01-08    51.73 Name: JPM US SMALLER COMPANIES C ACC, dtype: float64 

Unfortunately, df.fillna does not appear to be working for me:

>>>df.fillna( t ).head() Out[1]:              JPM US SMALLER COMPANIES C ACC 1990-01-02                             NaN 1990-01-03                             NaN 1990-01-04                             NaN 1990-01-05                             NaN 1990-01-08                             NaN  [5 rows x 1 columns] 

Why is this happening? I am on pandas 0.13.1

Answer 1

You need inplace=True

df[1].fillna(0, inplace=True) 

Answer 2

You need to assign the value df = df.fillna( t )