Here is a suggestion
> con <- textConnection("AnimalA,AnimalB,Score
A1,A2,1
A1,A3,2
A1,A4,3
A2,A3,4
A2,A4,5
A3,A4,6
")
> tst <- read.csv(con)
> close(con)
> an <- with(tst, sort(unique(c(as.character(AnimalA),
as.character(AnimalB)))))
> M <- array(0, c(length(an), length(an)), list(an, an))
> i <- match(tst$AnimalA, an)
> j <- match(tst$AnimalB, an)
> M[cbind(i,j)] <- M[cbind(j,i)] <- tst$Score
>
> M
A1 A2 A3 A4
A1 0 1 2 3
A2 1 0 4 5
A3 2 4 0 6
A4 3 5 6 0
>
Bill Venables
CSIRO Laboratories
PO Box 120, Cleveland, 4163
AUSTRALIA
Office Phone (email preferred): +61 7 3826 7251
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Mobile: +61 4 8819 4402
Home Phone: +61 7 3286 7700
mailto:[EMAIL PROTECTED]
http://www.cmis.csiro.au/bill.venables/
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
On Behalf Of knussear
Sent: Saturday, 10 May 2008 10:18 AM
To: r-help@r-project.org
Subject: [R] Create pairwise table from columns?
Hi Group
I have a large data set of individual pairwise values (250,000 rows)
that I
need to reshape into a pairwise matrix for mantel tests of these values
versus genetic distances.
the data are currently in columns formatted like so
AnimalA, AnimalB, Score
A1, A2, S1
A1, A3, S2
A1, A4, S3
A2, A3, S4
A2, A4, S5
A3, A4, S6
...,....,....
I need the final matrix to be formatted as
A1 A2 A3 A4
A1 0 S1 S2 S3
A2 S1 0 S4 S5
A3 S2 S4 0 S6
A4 S3 S4 S6 0
are there any functions/packages that will make this easier?
Thanks
Ken
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PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
