Flatten DataFrame into a single row

Question

I want to reorganize the following mutli-row DataFrame,

       1          2       3
A  Apple     Orange   Grape
B    Car      Truck   Plane
C  House  Apartment  Garage

into this, single-row DataFrame.

     1_A     2_A    3_A  1_B    2_B    3_B    1_C        2_C     3_C
0  Apple  Orange  Grape  Car  Truck  Plane  House  Apartment  Garage

Thank you for your help!

Answer 1

unstack + sort_index to the rescue:

v = df.unstack().to_frame().sort_index(level=1).T
v.columns = v.columns.map('_'.join)

v
     1_A     2_A    3_A  1_B    2_B    3_B    1_C        2_C     3_C
0  Apple  Orange  Grape  Car  Truck  Plane  House  Apartment  Garage