[R] Question about setdiff()

[Pascal Oettli]

Hello,

>From the help page: "Performs *set* union, intersection, (asymmetric!)
difference, equality and membership on two vectors."

Hope this helps,
Pascal


On Mon, Jun 2, 2014 at 3:57 PM, Raphael Päbst <raphael.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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-- 
Pascal Oettli
Project Scientist
JAMSTEC
Yokohama, Japan