pandas replace null values for a subset of columns

Question

I have a data frame with many columns, say:

df:
name   salary  age   title
John      100   35    eng
Bill      200  NaN    adm
Lena      NaN   28    NaN
Jane             


        

Answer 1

Try this:

df.loc[:, ['salary', 'age']].fillna(-1, inplace=True)