Unique values within Pandas group of groups
问题 I have a dataframe that I need to group, then subgroup. From the subgroups I need to return what the subgroup is as well as the unique values for a column. df = pandas.DataFrame({'country': pandas.Series(['US', 'Canada', 'US', 'US']), 'gender': pandas.Series(['male', 'female', 'male', 'female']), 'industry': pandas.Series(['real estate', 'shipping', 'telecom', 'real estate']), 'income': pandas.Series([1, 2, 3, 4])}) def subgroup(g): return g.groupby(['gender']) s = df.groupby(['country'])