I have the following dict that contains user name (key) and subreddits list[value]: {user1:[sub1, sub2, sub3...., subn], user2:[sub1, sub3, sub100, ..., subx],....}
I also have this as dataframe with columns 'user' and 'subreddits' (subreddits is a string but can be converted to list of strings like in the dict if it matters).
I need to convert them to 2 sparse matrix and then multiply and get argmax for each row. the axis are the subreddits and the rows are the users name. It's important to know the i and j at all time because the goal is to find users with same subreddits.
How should I approach this? Thanks!