On May 20, 2010, at 7:30 PM, Nordlund, Dan (DSHS/RDA) wrote:
-----Original Message-----
From: r-help-boun...@r-project.org [mailto:r-help-boun...@r-
project.org] On Behalf Of Jonathan
Sent: Thursday, May 20, 2010 3:25 PM
To: David Winsemius
Cc: r-help
Subject: Re: [R] intersect() without discarding duplicates?
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.
Best,
Jonathan
I think you have misread the intersect documentation. Given your
examples above intersect is what you in fact want.
a <- c(2,4,3)
b<-c(6,6,5,2,2,8,4)
intersect(a,b)
[1] 2 4
He wants this result.
> a <- c(2,4,2,3)
> b<-c(6,6,5,2,2,8,4)
> somefn(a,b)
[1] 2 4 2
And this result:
> a <- c(2,4,3)
> b<-c(6,6,5,2,2,8,4)
> somefn(a,b)
[1] 2 4
>somefn(b,a)
[1] 2 4
Hope this is helpful,
Dan
Daniel J. Nordlund
Washington State Department of Social and Health Services
Planning, Performance, and Accountability
Research and Data Analysis Division
Olympia, WA 98504-5204
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David Winsemius, MD
West Hartford, CT
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