How to get rows in a column in Pandas DataFrame

Question

I am trying to restructure a pandas data frame. Let's say, I have the below data frame;

uri	ID1	ID2	ID3
aaa	1	2	3
bbb	4	5	6

I am trying to restructure as below;

uri	IDs
aaa	1
aaa	2
aaa	3
bbb	4
bbb	5
bbb	6

I know the transform function but it is not doing what I want. Can anyone please help me?

Answer 1

Use stack:

>>> df.set_index('uri').stack().droplevel(1).rename('IDs').reset_index()
   uri  IDs
0  aaa    1
1  aaa    2
2  aaa    3
3  bbb    4
4  bbb    5
5  bbb    6