Completely new to R. Can't upload a sample of the data I am looking at as markdown not working. I have a set of blood test results eg FBC, UE approximately 9 episodes per blood test per patient, all in date format. I need to know which dates are the same and count per patient how many different dates there are.
I don't have an index date of diagnosis.
How do I set the earliest date per row and count how many from that are done per row?
Thank you anyone that can help with what is probably an easy task!