Hi, May be this helps: library(gtools) as.data.frame(t(combinations(5,3,1:5))) # V1 V2 V3 V4 V5 V6 V7 V8 V9 V10 #1 1 1 1 1 1 1 2 2 2 3 #2 2 2 2 3 3 4 3 3 4 4 #3 3 4 5 4 5 5 4 5 5 5 A.K.
For a column of data, I need to extract all possible unique combinations of 3 rows and combine the results into a data frame (as columns). So, for example, if I had a column called "test" that had five rows (the contents of which were the numbers 1:5) all possible combinations of 3 rows would be 1,2,3 1,2,4 1,2,5 1,3,4 1,3,5 1,4,5 2,3,4 2,4,5 2,4,5 3,4,5 So for this example, R would extract all the combinations shown, and I would get a data frame that looked like this 1 1 1 1 1 1 2 2 2 3 2 2 2 3 3 4 3 3 4 4 3 4 5 4 5 5 4 5 5 5 Note: I am not considering rearrangements of the same three rows to be unique. In other words, the combinations 123, 132, 213, 231, 312, 321 are all the same as far as I am concerned. If it is not possible to do it that way, it will still be helpful, but not quite as helpful. Thanks for the help! ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.