Question

duplicated() gives TRUE or FALSE statement depending if that position is duplicated previously in the vector. What if I wanted to remove not only the duplicated position, but also all the previous position that it is a duplicate of.

a <- c("A", "B", "C")
b <- c("A", "B", "C", "D")

a contains all the values that will be duplicated and b contains the values of a and some other values that are not duplicated.

How do I only extract "D"?

Answer 1

Here is another one:

b[!b %in% a]
[1] "D"