python - Pandas - combine two columns

Question

I have 2 columns, which we'll call x and y. I want to create a new column called xy:

x    y    xy
1         1
2         2

     4    4
     8    8

There shouldn't be any conflicting values, but if there are, y takes precedence. If it makes the solution easier, you can assume that x will always be NaN where y has a value.

Answer 1

it could be quite simple if your example is accurate

df.fillna(0)      #if the blanks are nan will need this line first
df['xy']=df['x']+df['y']