[R] Question about setdiff()

[arun]

Hi,
Please check this link:
http://r.789695.n4.nabble.com/meaning-of-asymmetric-on-help-page-for-intersect-td877408.html

union(setdiff(v,w), setdiff(w,v))


#or in this case

setdiff(union(v,w),intersect(v,w))
#or
 setdiff(c(v,w),c(v,w)[duplicated(c(v,w))])
A.K.


.paebst at gmail.com> wrote:

Hello everyone, I have a question which is probably rooted in my lack
of understanding when it comes to math.

I just did the following:

v <- c(1:20)
w <- c(11:30)
setdiff(v, w)

and got:
1 2 3 4 5 6 7 8 9 10

Then I did the following:
setdiff(w, v)
and got, not surprisingly:
21 22 23 24 25 26 27 28 29 30

Now I was originally expecting to get bot with the first call of
setdiff(v, w) and couldn't find any reason not to expect this from
?setdiff()

Am I missing somethin vital here or does setdiff() always give me the
elements of the first set that are not in the second one and not those
which are exclusive to either one, just dropping the ones in the
intersection of both sets?

Many Thanks in advance

Raphael

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