### Name: sets
### Title: Set Operations
### Aliases: union intersect setdiff is.element setequal
### Keywords: misc

### ** Examples

(x <- c(sort(sample(1:20, 9)),NA))
(y <- c(sort(sample(3:23, 7)),NA))
union(x, y)
intersect(x, y)
setdiff(x, y)
setdiff(y, x)
setequal(x, y)

## True for all possible x & y :
setequal( union(x,y),
          c(setdiff(x,y), intersect(x,y), setdiff(y,x)))

is.element(x, y)# length 10
is.element(y, x)# length  8