[R] Transform pairwise observations into a table

arun smartpink111 at yahoo.com
Mon Oct 1 18:53:39 CEST 2012

```Hi,
Try this:

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
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 -----
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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