Dataframes in R

This is my first time posting, so go easy on me.

I have got the data frame (as shown on the link, I don't have enough rep points to link an image yet). I am trying to run some course wise analysis. Issue is that I have got a few students who are doing dual degrees, and as such need to appear in calculations for both departments. Dataframe

I am trying to figure out how to do that.

I am think I can write a stopgate statement where syntax checks if the Course2 column is empty or not before doing the analysis for each course. I cannot quite figure out how to do it.

Any help is appreciated.

Thank you.