I try to use mutate in dplyr library but, I am having an error message, where am I doing mistake? I just try to add 1 more column as a name E, and the rule is; if Visit == BLR or F04,E is 1 or if visit == F12 or F16 E is 2 or Visit == F16 or F20 E is 3. You can see also my input data and expected output data.
inp<-data.frame(MaskID = c(10,10,10,10,12,2),Visit = c("BLR", "F04", "F16", "F20", "F12", "F20"),SBP = c(8,7,6,12,11,21))
inp %>% group_by(MaskID) %>% mutate(E = ifelse( Visit == c("BLR" | "F04"), 1,ifelse(Visit == c("F08" | "F12"), 2,3)))
out <- data.frame(MaskID = c(10,10,10,10,12,12),Visit = c("BLR", "F04", "F16", "F20", "F12", "F20"), SBP = c(8,7,6,12,11,21), E = c(1,1,3,3,2,3 ))