# find unique elements in pandas and their connection with other column

df = pd.DataFrame({'author':['a', 'a', 'b'], 'subreddit':['sr1', 'sr2', 'sr2']}) >>> df author subreddit 0 a sr1 1 a sr2 2 b sr2 ...

**Here is what the above code is Doing:**

1. Create a dataframe with two columns, author and subreddit.

2. Create a new column, author_subreddit, which is the concatenation of author and subreddit.

3. Group by author_subreddit and count the number of rows in each group.

4. Sort the dataframe by the count column in descending order.

5. Reset the index so that the index is a range from 0 to the number of rows.

6. Drop the count column.

7. Rename the author_subreddit column to author.

8. Rename the index column to subreddit.

9. Sort the dataframe by subreddit in ascending order.

10. Print the dataframe.