Having two vectors is there a nicer way to test if one is included in another?

Question

Given two vectors:

x = c('a','b')
lookup = c('a','c','d','e','f')

test if each element in x is present in lookup . One way of doing it:

all(!is.na(match(x, lookup)))

I find this solution a bit verbose for R and wonder if there is better/shorter version.

Answer 1

%in% does this:

all(x %in% lookup)
## [1] FALSE

Answer 2

Can also use setdiff . See the associated help page for other set operations.

setdiff(x,lookup)
[1] "b"
> as.logical(length( setdiff(x,lookup) ) )
[1] TRUE