DevStarSJ

# df : len(unique(index.id1)) 16000, len(unique(index.id1)) 67000

# loop for id2

# test 1. make sub df for id2

A = time.time()
for id2 in df.index.get_level_values('id2'):
    df_id2 = df.loc[df.index.get_level_values('id2') == id2]
    

DevStarSJ

# pandas DataFrame iterate rows and assign to new column test
# - data size : 329 rows
#    - unique of index one : 91
#    - unique of index one : 329
# - iteration way
#    - using index
#      - make sub df one depth
#      - make sub df two depth
#      - using df index
#      - groupby one level