Add recurring index to pandas multi indexed dataframe while keeping the order -

i add new column dataframe belwow name new_col contain number of entry in last index (while keeping order or ordering them ordered update time each sub group). result should below show in new_col.

                                             update_time             new_col   book_name business_date      measure_def_id                   144       02-nov-16 12:00:00 pnl            02-nov-16 05:30:24       1                                             03-nov-16 05:30:29       2                                             04-nov-16 04:38:46       3                              risk           02-nov-16 09:32:26       1                                             03-nov-16 09:31:49       2                                             03-nov-16 11:08:17       3 

i think need set_index:

print (df.set_index('new_col', append=true))                                                             update_time book_name business_date      measure_def_id new_col                     144       02-nov-16 12:00:00 pnl            1        02-nov-16 05:30:24                                             2        03-nov-16 05:30:29                                             3        04-nov-16 04:38:46                              risk           1        02-nov-16 09:32:26                                             2        03-nov-16 09:31:49                                             3        03-nov-16 11:08:17 

you need cumcount creating series last level of index:

print (df.set_index(df.groupby(level=[0,1,2]).cumcount() + 1, append=true))