I like the example provided by David L. Carlson using the function
'expand.grid()' as shown in the previous email.
You may try 'outer()' and 'upper.tri()' instead 'expand.grid()'. Please
see the below:
> x <- outer(test, test, paste, sep=",")
> x
[,1] [,2] [,3] [,4] [,5]
[1,] "1,1" "1,5001" "1,10001" "1,15001" "1,20001"
[2,] "5001,1" "5001,5001" "5001,10001" "5001,15001" "5001,20001"
[3,] "10001,1" "10001,5001" "10001,10001" "10001,15001" "10001,20001"
[4,] "15001,1" "15001,5001" "15001,10001" "15001,15001" "15001,20001"
[5,] "20001,1" "20001,5001" "20001,10001" "20001,15001" "20001,20001"
[6,] "25001,1" "25001,5001" "25001,10001" "25001,15001" "25001,20001"
[,6]
[1,] "1,25001"
[2,] "5001,25001"
[3,] "10001,25001"
[4,] "15001,25001"
[5,] "20001,25001"
[6,] "25001,25001"
> x.idx <- upper.tri(x, diag=FALSE)
> x[x.idx]
[1] "1,5001" "1,10001" "5001,10001" "1,15001" "5001,15001"
[6] "10001,15001" "1,20001" "5001,20001" "10001,20001" "15001,20001"
[11] "1,25001" "5001,25001" "10001,25001" "15001,25001" "20001,25001"
> x.idx2 <- upper.tri(x, diag=TRUE)
> x[x.idx2]
[1] "1,1" "1,5001" "5001,5001" "1,10001" "5001,10001"
[6] "10001,10001" "1,15001" "5001,15001" "10001,15001" "15001,15001"
[11] "1,20001" "5001,20001" "10001,20001" "15001,20001" "20001,20001"
[16] "1,25001" "5001,25001" "10001,25001" "15001,25001" "20001,25001"
[21] "25001,25001"
>
I hope this helps. Thank you, David, for your good lesson.
Chel Hee Lee, PhD.
Biostatistian and Manager
Clinical Research Support Unit
College of Medicine
University of Saskatchewan
On 12/18/2014 9:16 AM, David L Carlson wrote:
Depending on what you want, you probably want to start with expand.grid():
# All combinations of test with test
pairs1 <- expand.grid(test, test)
nrow(pairs1)
[1] 36
# Exclude cases that differ only in the order of the values
# E.g. (1, 5001), but not (5001, 1), also (1, 1), etc are included
pairs2 <- pairs1[pairs1[,1] <= pairs1[,2],]
nrow(pairs2)
[1] 21
# Same as pairs2 but (1, 1), etc are not included
pairs3 <- pairs1[pairs1[,1] < pairs1[,2],]
nrow(pairs3)
[1] 15
-------------------------------------
David L Carlson
Department of Anthropology
Texas A&M University
College Station, TX 77840-4352
-----Original Message-----
From: R-help [mailto:r-help-boun...@r-project.org] On Behalf Of Sarah Goslee
Sent: Thursday, December 18, 2014 9:06 AM
To: Alaios
Cc: R-help@r-project.org
Subject: Re: [R] combinations between two vectors
I can't quite tell what you want: your example output is either
unclear to me or mangled by posting in HTML (please don't).
Is
expand.grid(test, test)
what you want, or partway to what you want?
Sarah
On Thu, Dec 18, 2014 at 9:56 AM, Alaios via R-help <r-help@r-project.org> wrote:
Hi all,I am looking for a function that would give me all the combinations
between two vectors.Lets take as example the
test<-seq(1,30000,by=5000)
Browse[2]> test
[1] 1 5001 10001 15001 20001 25001
I want all the combinations between two times the test... I think this is
called permutation so a function that could do permutation(test,test)and
produce the following
1,11,50011,100011,15001....
3,13,5001...25001,20001,25001,25001
is there such a function ?
RegardsAlex
[[alternative HTML version deleted]]
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