Listing unique elements over multiple vectors in R

Question

I have three vectors (a, b, and c) and found the common elements in all three using

common<-Reduce(intersect,list(a,b,c))

I want to find out now which elements are unique to a. I can't use a[!(a%in%common)] since that could return elements in a and one other vector.

I don't think this is a new or unique question, but part of my problem in finding the answer is that I'm not sure what the a[!(a%in%common)] function is called.

Answer 1

You can use reduce and setdiff for an arbitrary length list

Reduce(setdiff, list(a,b,c))

Answer 2

The simple solution would be a[!(a %in% union(b,c))].