On May 20, 2010, at 7:10 PM, David Winsemius wrote:
On May 20, 2010, at 6:24 PM, Jonathan wrote:
Thanks, but that doesn't quite work, since I'd want the result of
b[b %in% a] to be symmetric with a[a%in%b] (so if there are two 2's
in EACH vector, I'll get two 2's in the result, but if there are two
2's in only one vector, but one two in the other, the result will
show only one 2.
Consider:
a <- c(2,4,3)
b<-c(6,6,5,2,2,8,4)
b[b %in% a]
[1] 2 2 4
a[a%in%b]
[1] 2 4
The second answer is correct, but I can't predict which variable to
put in which position in the statement, so I'd need them both to be
correct.
Perhaps you should look at something along the lines of :
a <- c(2,4,2,3)
b<-c(6,6,5,2,2,8,4)
a[a %in% b]
[1] 2 4 2
merge(data.frame(table(a)), data.frame(table(b)), by.x="a",
by.y="b" )
a Freq.x Freq.y
1 2 2 2
2 4 1 1
And then do a pmin() on the Freq's
somefn <- function(a,b) { xtb <- merge(data.frame(table(a)),
data.frame(table(b)), by.x="a",
by.y="b" );
rep(xtb[,1], pmin(xtb[,2], xtb[,3]) )}
> somefn(a,b)
[1] 2 2 4
Levels: 2 3 4
> somefn(b,a)
[1] 2 2 4
Levels: 2 4 5 6 8
> a <- c(2,3,4)
> somefn(b,a)
[1] 2 4
Levels: 2 4 5 6 8
> somefn(a,b)
[1] 2 4
Levels: 2 3 4
If you wanted it as a vector, then wrap in as.numeric(as.character( ) )
--
David.
Best,
Jonathan
On Thu, May 20, 2010 at 6:10 PM, David Winsemius <dwinsem...@comcast.net
wrote:
On May 20, 2010, at 5:58 PM, Jonathan wrote:
Hi all,
The ?intersect entry kindly points out that it discards duplicate
entries. I'm looking, however, to get the intersection while KEEPING
duplicate entries, and there are no instructions on how to
accomplish this
using intersect().
Does anybody have any idea how this might be done, or am I going to
need to
program something from scratch (something like ordering the vectors
and then
looping through them)?
ex:
a <- c(2,4,2,3)
b<-c(6,6,5,2,2,8,4)
intersect(a,b)
[1] 2 4
b %in% a
[1] FALSE FALSE FALSE TRUE TRUE FALSE TRUE
# Now use logical indexing on "b"
b[b %in% a]
[1] 2 2 4
I'd hope the answer to be 2 2 4.
Regards,
Jonathan
[[alternative HTML version deleted]]
______________________________________________
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.
David Winsemius, MD
West Hartford, CT
David Winsemius, MD
West Hartford, CT
[[alternative HTML version deleted]]
______________________________________________
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.
David Winsemius, MD
West Hartford, CT
______________________________________________
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.
