[R] meaning of asymmetric on help page for intersect

[Prof Brian Ripley]

Because there is also a symmetric difference: see

http://en.wikipedia.org/wiki/Symmetric_difference

> Sorry if this is a silly question. What does asymmetric refer to from
> ?intersect, and are there any
> aspects of the result that may be different from expected (reason for
> exclamation point) ?
>
> As toy data, if needed, here are the examples from the help page.
>
> (x <- c(sort(sample(1:20, 9)),NA))
> (y <- c(sort(sample(3:23, 7)),NA))
>
> Thanks,
>
> Juliet

-- 
Brian D. Ripley,                  ripley at stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
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