Hi Alex, Here is a suggestion:
apply(combn(idx, 2), 2, paste, collapse = ".") See ?combn, ?apply and ?paste for more information. HTH, Jorge On Thu, Jun 3, 2010 at 3:08 PM, Alex van der Spek <> wrote: > I can get the interactions between factors like this: > > > idx=c(1,3,6,9) > > jdx=idx > > levels(interaction(idx,jdx,lex.order=TRUE)) > [1] "1.1" "1.3" "1.6" "1.9" "3.1" "3.3" "3.6" "3.9" "6.1" "6.3" "6.6" > "6.9" > [13] "9.1" "9.3" "9.6" "9.9" > > This list contains all possible interactions. Whereas I need only the > combinations, e.g 4 over 2 = 6 total being > > "1.3 " "1.6" "1.9" "3.6" "3.9" "6.9" > > I have been unable to find how to get the combinations. Of course with some > string manipulations this can be done for this toy example. There should be > something in R to make this easy? > > Thanks in advance > Alex van der Spek > > ______________________________________________ > 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. > [[alternative HTML version deleted]] ______________________________________________ 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.
