Dear RStudio Community,
For my master thesis I am currently working with a patent dataset with variables like the publication year and the different classification codes (or IPCs) per patent. For my current analysis I need to know how many unique (or distinct) IPC codes are used PER YEAR. So, for example, my dataset has multiple rows regarding to patents from year 1899. All these patents from 1899 have multiple (and sometimes the same) IPC codes. Now I need to know how many different IPC codes have been used in 1899 (and all other years in the dataset). Below is a small example of the data.
Eventually I would like to receive a simple table with the different years and the amount of different IPC codes used per year.
I am very new to RStudio and got kind of lost in all the coding and so forth. It would be a lifesaver if I could receive help to get this information out of my dataset.