Along the same line as @nirgrahamuk, ifelse
seems more appropriate, especially because you can ignore else if
completely. If you are actually passing Meditation
as a vector (as opposed to scalar) to the function, something like this is likely to do the job:
ifelse(Mediation %in% c("Medication Prior to Start of Visit", "Medication after start of Visit"), End_Date - Start_Date, -1)
The advantage of %in%
is that it will not return NA
even if Meditation
contains NA
, and will return FALSE
in that case.
For your future posts, consider providing a reproducible example of your problem, regarding which there is a detailed guide here. And, welcome to the community!