[R] Transform pairwise observations into a table

[arun]

HI AHJ,
No problem.

One more way in addition to reshape() (Rui's suggestion) to get the same result.
library(reshape)

as.matrix(cast(melt(dat1,id=c("ind1","ind2")),ind1~ind2,value="value"))
#      1     2     3   4
#1 1.000 0.250 0.125 0.5
#2 0.250 1.000 0.125 0.5
#3 0.125 0.125 1.000 0.5
#4 0.500 0.500 0.500 1.0
A.K.



----- Original Message -----
From: "Hadjixenofontos, Athena" <AHadjixenofontos at med.miami.edu>
To: arun <smartpink111 at yahoo.com>
Cc: R help <r-help at r-project.org>
Sent: Monday, October 1, 2012 12:59 PM
Subject: Re: [R] Transform pairwise observations into a table

Thank you. I had looked at xtabs but misunderstood the syntax. This is great. :)

AHJ



On Oct 1, 2012, at 12:53 PM, "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
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> 
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