问题
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.
回答1:
You can use setdiff
setdiff(b,a)
#[1] 2 6 8
回答2:
An alternative way, instead of setdiff (which is probably preferrable), is to use %in%
unique(b[! b %in% a])
#[1] 2 6 8
来源：https://stackoverflow.com/questions/31573087/difference-between-two-vectors-in-r