How to show up the duplicate?

[Jack_Sparrow]

Hi there,
this is my data set:
user_id timestamp group landing_page converted
0 851104 2017-01-21 22:11:48.556739 control old_page 0
1 804228 2017-01-12 08:01:45.159739 control old_page 0
2 661590 2017-01-11 16:55:06.154213 treatment new_page 0
3 853541 2017-01-08 18:28:03.143765 treatment new_page 0
4 864975 2017-01-21 01:52:26.210827 control old_page 1

I know there is one duplicate in user_id. I check it with this query:

sum(df2.user_id.duplicated())

Now I want to know this user id. How can I do this?

Thanks in advance!

[mlieqo]

Hello, you can use filter:

ids = df2['user_id']
ids_duplicates = df2[ids.isin(ids[ids.duplicated()])]

this will return all the rows where user_id is one of the duplicates and you can easily get unique user_id values out of there:

list(set(ids_duplicates.user_id))