How to sum 2 pandas Series with diffent rows treating NaN as 0

Question

I have 2 pandas Series, like this

bananas    3.0
apples     2.0
avocados   4.0

bananas     2.0
apples      5.0
pineapple   1.0

If I just sum them, it returns this:

apples      7.0
avocados    NaN
bananas     5.0
pineapple   NaN

but what I want is

apples      7.0
avocados    4.0
bananas     5.0
pineapple   1.0

user_4238408 · Answer

Try concat with groupby:

pd.concat([s1,s2]).groupby(level=0).sum()

Or .add with fill_value option:

s1.add(s2, fill_value=0)