Pandas: Multiple columns into one column

Question

I have the following data (2 columns, 4 rows):

Column 1: A, B, C, D  Column 2: E, F, G, H 

I am attempting to combine the columns into one column to look like this (1 column, 8 rows):

Column 3: A, B, C, D, E, F, G, H 

I am using pandas DataFrame and have tried using different functions with no success (append, concat, etc.). Any help would be most appreciated!

Answer 1

The trick is to use stack()

df.stack().reset_index()         level_0   level_1  0 0        0  Column 1  A 1        0  Column 2  E 2        1  Column 1  B 3        1  Column 2  F 4        2  Column 1  C 5        2  Column 2  G 6        3  Column 1  D 7        3  Column 2  H 

Answer 2

Update

pandas has a built in method for this stack which does what you want see the other answer.

This was my first answer before I knew about stack many years ago:

In [227]:  df = pd.DataFrame({'Column 1':['A', 'B', 'C', 'D'],'Column 2':['E', 'F', 'G', 'H']}) df Out[227]:   Column 1 Column 2 0        A        E 1        B        F 2        C        G 3        D        H  [4 rows x 2 columns]  In [228]:  df['Column 1'].append(df['Column 2']).reset_index(drop=True) Out[228]: 0    A 1    B 2    C 3    D 4    E 5    F 6    G 7    H dtype: object