self-join with Pandas

Question

I would like to perform a self-join on a Pandas dataframe so that some rows get appended to the original rows. Each row has a marker \'i\' indicating which row should get ap

Answer 1

Instead of using merge you can also use indexing and assignment:

>>> d['new_col'] = d['some_col'][d['i']].values
>>> d
  some_col  i new_col
0        A  2       C
1        B  1       B
2        C  1       B