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Transform pairwise observations into a table

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



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