how to find elements from a list that are not present in another list in r

Question

I have two lists that have the same vectors but with different length

list1 <- list(a = 1:10, b = 3:20)
list2 <- list(a = c(2,5,8), b = c(3,5,11,20))
<         


        

Answer 1

We can use

mapply(setdiff,list1,list2)
#$a
#[1]  1  3  4  6  7  9 10

#$b
#[1]  4  6  7  8  9 10 12 13 14 15 16 17 18 19