Difference between two vectors in R

Question

I have two vectors:

a <- c(1, 1, 3, 4, 5, 7, 9)
b <- c(2, 3, 4, 6, 8, 2)

I want to find the numbers in the second vector, which are not in the first vector:

dif <- c(2, 6, 8)

I've tried many different approaches (such as merge, different types of joins (dplyr package), setdiff, compare (compare package)), but I still can't find a way to do it.

Answer 1

You can use setdiff

setdiff(b,a)
#[1] 2 6 8

Answer 2

An alternative way, instead of setdiff (which is probably preferrable), is to use %in%

unique(b[! b %in% a])
#[1] 2 6 8