pandas sort_values is always sorting by date in Ascending-CodePudding

Below pandas query is not sorting in descending date wise. Even when I use ascending=False, it is showing data in ascending datewise order.

I even converted date columns which was object type to datetime as below -

final_data['date'] = pd.to_datetime(final_data['date'])

all_users_list = final_data.sort_values(by='date', ascending=False).groupby(['user_id','date','content_id'])['user_id','content_id','date'].apply(list)

Output Sample:

user_id                date        content_id     
user_10013             2018-02-03  cont_3189_6_12     [user_id, content_id, date]
                       2018-04-10  cont_2244_16_1     [user_id, content_id, date]
                       2018-08-13  cont_300_1_1       [user_id, content_id, date]
                       2018-09-11  cont_2233_3_8      [user_id, content_id, date]
                       2018-12-04  cont_2597_6_8      [user_id, content_id, date]
                       2019-02-02  cont_2573_4_15     [user_id, content_id, date]
                       2019-04-14  cont_4860_7_1      [user_id, content_id, date]
                       2019-04-29  cont_2270_9_2      [user_id, content_id, date]
                       2019-11-26  cont_2700_3_11     [user_id, content_id, date]
                       2019-12-05  cont_2946_6_43     [user_id, content_id, date]
                       2019-12-07  cont_73_1_2        [user_id, content_id, date]
                       2020-03-12  cont_2975_3_36     [user_id, content_id, date]
                       2020-09-17  cont_420           [user_id, content_id, date]
                       2020-10-17  cont_3036_5_14     [user_id, content_id, date]
                       2020-11-01  cont_4037_1_31     [user_id, content_id, date]
                       2021-02-17  cont_761_1_2       [user_id, content_id, date]
                       2021-05-19  cont_4444_3_21     [user_id, content_id, date]
                       2021-05-21  cont_2911_14_14    [user_id, content_id, date]
                       2021-07-24  cont_2227_7_18     [user_id, content_id, date]
                       2021-08-19  cont_286_17_21     [user_id, content_id, date]
                       2021-10-07  cont_4148_4_22     [user_id, content_id, date]
user_10034             2019-01-06  cont_160_1_5       [user_id, content_id, date]
                       2019-03-30  cont_1877_2_6      [user_id, content_id, date]
                       2019-04-05  cont_4550_1_5      [user_id, content_id, date]
                       2019-04-26  cont_3352_17_15    [user_id, content_id, date]
                       2019-05-10  cont_363_1_3       [user_id, content_id, date]
                       2019-05-11  cont_56_11_13      [user_id, content_id, date]
                       2019-08-27  cont_4812_2_13     [user_id, content_id, date]
                       2019-09-12  cont_13_1_3        [user_id, content_id, date]
                       2019-09-13  cont_4435_7_7      [user_id, content_id, date]
                       2019-09-22  cont_4453_12_4     [user_id, content_id, date]
                       2019-10-28  cont_4375_1_23     [user_id, content_id, date]
                       2019-12-25  cont_3356_6_14     [user_id, content_id, date]
                       2020-02-16  cont_2853_3_22     [user_id, content_id, date]
                       2020-04-15  cont_1452_4_22     [user_id, content_id, date]
                       2020-04-27  cont_3331_5_4      [user_id, content_id, date]
                       2020-05-06  cont_4857_13_24    [user_id, content_id, date]
                       2020-05-28  cont_3885_1_4      [user_id, content_id, date]
                       2020-06-22  cont_4472_1_33     [user_id, content_id, date]
                       2020-07-03  cont_4082_9_36     [user_id, content_id, date]
                       2020-08-15  cont_4358_5_20     [user_id, content_id, date]
                       2020-09-03  cont_4952_1_6      [user_id, content_id, date]
                       2021-01-13  cont_935_19_4      [user_id, content_id, date]
                       2021-03-03  cont_1063_1_14     [user_id, content_id, date]

What could be the issue and how to resolve this please?

CodePudding user response：

Try using sort=False in groupby:

all_users_list = final_data.sort_values(by='date', ascending=False).groupby(['user_id','date','content_id'], sort=False)['user_id','content_id','date'].apply(list)

Or sort after the groupby:

all_users_list = final_data.groupby(['user_id','date','content_id'], sort=False)['user_id','content_id','date'].apply(list).sort_index(level="date", ascending=False)