efficiently flatten multiple columns into a single row in pandas

Question

How can I efficiently "flatten" multiple columns of a dataframe into a single row?

	A	B
1	'a'	'b'
2	'c'	'd'

To:

A_1	A_2	B_1	B_2
'a'	'c'	'b'	'd'

Answer 1

Create Series with MultiIndex by DataFrame.unstack , convert to DataFrame and transpose, last flatten MultiIndex :

df = df.unstack().to_frame().T
df.columns = df.columns.map(lambda x: f'{x[0]}_{x[1]}')
print (df)
   A_1  A_2  B_1  B_2
0  'a'  'c'  'b'  'd'