Unique Count

[Talch]

Good afternoon All,

A bit of a newbie in python, so looking for a bit of help with a unique count problem.

I am using the following code on a dataframe:

Stats.groupby('subject_user')[['clicked_user']].count() , which groups by the subject user column and does a count of the clicked user.

How do I tweak this so that:

a) It counts only the unique "clicked-user"


Thank you

Talch