Create pairwise table from columns?
On Fri, May 9, 2008 at 7:17 PM, knussear <knussear at mac.com> wrote:
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
One approach would be to use the reshape package (http://had.co.nz/reshape) - dfm <- melt(mydf, id = c("AnimalA", "AnimalB")) cast(dfm, AnimalA ~ AnimalB) Hadley