On 1/13/2009 10:41 AM, Juliet Hannah wrote:
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) ?
There are two definitions for a set difference: the symmetric one and the asymmetric one.
R uses the asymmetric one, so setdiff(A, B) is the intersection of A with the complement of B. (The complement is taken in the union of A and B).
The symmetric difference is described on the Wikipedia page http://en.wikipedia.org/wiki/Symmetric_difference. In R, you could get it as
union(setdiff(A, B), setdiff(B, A)) Duncan Murdoch
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 ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
