r - Finding strings not %in% other vector of strings -

this question has answer here:

• generating vector of difference between 2 vectors 2 answers

if have vector of strings , want know match. it's simple matter of using %in%.

x <- c("red","blue","green") y <- c("yellow","blue","orange")  which(x %in% y) # literally, x in y. 

but opposite, find x not in y?

a neat way (that learnt @joran, iirc) is:

`%nin%` <- negate(`%in%`) which(x %nin% y) [1] 1 3