[R] Transform pairwise observations into a table

[Bert Gunter]

You might be amused by this alternative:

with(dat1,matrix(coef[order(ind2,ind1)],nr=4,nc=4))

It works because matrices are vectors stored in column major order.

Cheers,
Bert


On Mon, Oct 1, 2012 at 9:53 AM, arun <smartpink111 at yahoo.com> wrote:
> Hi,
> Try this:
>
> dat1<-read.table(text="
> ind1 ind2 coef
> 1 1 1
> 1 2 0.25
> 1 3 0.125
> 1 4 0.5
> 2 2 1
> 2 1 0.25
> 2 3 0.125
> 2 4 0.5
> 3 3 1
> 3 1 0.125
> 3 2 0.125
> 3 4 0.5
> 4 4 1
> 4 1 0.5
> 4 2 0.5
> 4 3 0.5
> ",sep="",header=TRUE)
> mat1<-as.matrix(xtabs(coef~ind1+ind2,data=dat1))
>
> #    ind2
> #ind1     1     2     3     4
>   # 1 1.000 0.250 0.125 0.500
>    #2 0.250 1.000 0.125 0.500
>    #3 0.125 0.125 1.000 0.500
>    #4 0.500 0.500 0.500 1.000
>
> A.K.
>
>
>
> ----- Original Message -----
> From: AHJ <ahadjixenofontos at med.miami.edu>
> To: r-help at r-project.org
> Cc:
> Sent: Monday, October 1, 2012 12:17 PM
> Subject: [R] Transform pairwise observations into a table
>
> Hi,
>
> I have a table of pairs of individuals and a coefficient that belongs to the
> pair:
>
> ind1    ind2    coef
> 1    1    1
> 1    2    0.25
> 1    3    0.125
> 1    4    0.5
> 2    2    1
> 2    1    0.25
> 2    3    0.125
> 2    4    0.5
> 3    3    1
> 3    1    0.125
> 3    2    0.125
> 3    4    0.5
> 4    4    1
> 4    1    0.5
> 4    2    0.5
> 4    3    0.5
>
> And I want to convert it to a matrix where each individual is both a row and
> a column and at the intersection of each pair is the coefficient that
> belongs to that pair:
>
>     1           2           3             4
> 1    1           0.25           0.125    0.5
> 2    0.25      1           0.125    0.5
> 3    0.125    0.125    1            0.5
> 4    0.5           0.5           0.5            1
>
> If table() would allow me to specify something other than frequencies to
> fill the table with, it would be what I need. I tried a few different
> combinations of t() and unique() but none of it made enough sense to post as
> my starting code... I am just lost. Any help would be greatly appreciated.
>
> Thank you,
> AHJ
>
>
>
> --
> View this message in context: http://r.789695.n4.nabble.com/Transform-pairwise-observations-into-a-table-tp4644706.html
> Sent from the R help mailing list archive at Nabble.com.
>
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>
>
> ______________________________________________
> R-help at r-project.org mailing list
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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.



-- 

Bert Gunter
Genentech Nonclinical Biostatistics

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