Columns manipulation - python

Question

Here is my dataset:

•  COL_1 COL_2 COL_3 COL_4 COL_5 COL_8 COL_9
   A col2 col3 col4 col5
   B col2 col3 col4 col5
   C col2 col3 col4 col5
  

I need to move pairs of columns (COL_2 , COL_3 and then COL_4, COL_5) to COL_8 and COL_9 and copy the content of the 1st column (COL_1):

•  COL_1 COL_8 COL_9
   A col2 col3
   B col2 col3
   C col2 col3
   A col4 col5
   B col4 col5
   C col4 col5
  

How can I do it using Python? Do I need to use loop or are there easier ways to do so?

Answer 1

Here's a solution:

cols = df.drop('COL_1', axis=1).columns
new_df = pd.concat([pd.concat([df[c] for c in cols[i::2]]) for i in [0,1]], axis=1).assign(A=df['COL_1'])[['A', 0, 1]].set_axis(['COL_1','COL_8','COL_9'], axis=1).reset_index(drop=True)

Output:

>>> new_df
 COL_1 COL_8 COL_9
0 A col2 col3
1 B col2 col3
2 C col2 col3
3 A col4 col5
4 B col4 col5
5 C col4 col5