Re: [R] give all combinations

From: ONKELINX, Thierry <Thierry.ONKELINX_at_inbo.be>
Date: Mon, 01 Sep 2008 10:12:41 +0200

A more generic solution is

allComb <- expand.grid(rep(list(letters[1:5]), 7)) whichComb <- sapply(seq_len(ncol(allComb) - 1), x = allComb, function(i, x){

    whichCombination <- sapply(seq(i + 1, ncol(x)), y = x, function(j, y){

        as.numeric(y[, i]) <= as.numeric(y[, j])     })
    apply(whichCombination, 1, all)
})
allComb[apply(whichComb, 1, all), ]

HTH, Thierry




ir. Thierry Onkelinx
Instituut voor natuur- en bosonderzoek / Research Institute for Nature
and Forest
Cel biometrie, methodologie en kwaliteitszorg / Section biometrics, methodology and quality assurance
Gaverstraat 4
9500 Geraardsbergen
Belgium
tel. + 32 54/436 185
Thierry.Onkelinx_at_inbo.be
www.inbo.be

To call in the statistician after the experiment is done may be no more than asking him to perform a post-mortem examination: he may be able to say what the experiment died of.
~ Sir Ronald Aylmer Fisher

The plural of anecdote is not data.
~ Roger Brinner

The combination of some data and an aching desire for an answer does not ensure that a reasonable answer can be extracted from a given body of data.
~ John Tukey

-----Oorspronkelijk bericht-----
Van: r-help-bounces_at_r-project.org [mailto:r-help-bounces_at_r-project.org] Namens Lucien Lemmens
Verzonden: zondag 31 augustus 2008 15:58 Aan: r-help_at_stat.math.ethz.ch
Onderwerp: Re: [R] give all combinations

Another solution requiring also a bit of programming is:

 l<-letters[1:3]
 c2<-c()
 for(i in 1:3){c2<-c(c2,paste(letters[i],letters[i:3],sep=""))}  c2
[1] "aa" "ab" "ac" "bb" "bc" "cc"
 n<-length(c2)
 c3<-c();for(i in
1:n){c3<-c(c3,paste(c2[i],letters[ceiling(i/2):3],sep=""))}  c3
 [1] "aaa" "aab" "aac" "aba" "abb" "abc" "acb" "acc" "bbb" "bbc" "bcc" "ccc"



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