I hacked at a bit differently than Duncan. See if these help pages and
this example point another way:
?combn
?"["
> df <- data.frame(a = 1:4, b=LETTERS[1:4])
> n <- nrow(df)
> cbind(df[combn(1:n,2)[1,],], df[combn(1:n,2)[2,],] )
a b a b
1 1 A 2 B
1.1 1 A 3 C
1.2 1 A 4 D
2 2 B 3 C
2.1 2 B 4 D
3 3 C 4 D
--
David Winsemius
On Mar 21, 2009, at 12:01 PM, Donald Macnaughton wrote:
I have a data frame with roughly 500 rows and 120 variables. I
would like
to generate a new data frame that will include one row for each PAIR
of
rows in the original data frame and will include all 120 + 120 = 240
variables from the two rows. I need only one row for each pair, not
two
rows. Thus the new data frame will contain 500 x 499 / 2 = 124,750
rows.
Is there an easy way to do this with R?
David Winsemius, MD
Heritage Laboratories
West Hartford, CT
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