How to find the difference between two csv files by index using Pandas?

Question

Python

It is necessary to (1) subtract from the csv with id and links of another cs with id, (2) delete cells without links and (3) duplicates.

I'm trying this method, but it adds the data instead of subtracting. As I understand it, because the second file does not contain the sites field. How to be?

df1 = pd.concat([df,cite_id]).drop_duplicates(keep=False)

df - frame with two columns.
cite_id - frame with one id column.