Pandas Outer merge

[Pedroski55]

Can't see how to get what you want, but somewhere near it.

Given

Output:
df1
  col1 col2
0    1    A
1    1    B
2    2    C
3    5    Z
4    4    Q

and

Output:
df2
  col1 col2
0    1    A
1    1    B
2    2    E
3    3    X
4    4    R
5    4    S

df3 = df1.merge(df2, how="outer", left_index=True, right_index=True, suffixes=('_left', '_right'))
df4 = df3[['col2_left', 'col2_right']]

Output:
df4
  col2_left col2_right
0         A          A
1         B          B
2         C          E
3         Z          X
4         Q          R
5       NaN          S