if i were to have a block size of 4 people and i want to assign a treatment
combination to the entire block, there would be 16 different treatment
combinations (TTTT, TTTP, TTPP, PTTP, etc.)
i am trying to get all 16 permutations and i am able to use this code below.
drugs=c('P','T');
comb=expand.grid(drugs,drugs,drugs,drugs)
for a block size of 3 the code would be comb=expand.grid(drugs,drugs,drugs)
and for a block size of 2 it would be comb=expand.grid(drugs,drugs).
my question is whether there is a way to automatically create the comb
variable. i tried using expand.grid(rep(drugs, block.size) but that didn't
work.
any help on how i can proceed? thanks
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On Wed, Oct 31, 2012 at 8:18 PM, trekvana <trekvana at aol.com> wrote:> if i were to have a block size of 4 people and i want to assign a treatment > combination to the entire block, there would be 16 different treatment > combinations (TTTT, TTTP, TTPP, PTTP, etc.) > > i am trying to get all 16 permutations and i am able to use this code below. > > drugs=c('P','T'); > comb=expand.grid(drugs,drugs,drugs,drugs)do.call(expand.grid, rep(list(drugs),n)) where n is 3,4,5... Cheers, Michael> > -- > View this message in context: http://r.789695.n4.nabble.com/expand-grip-for-permutations-tp4648067.html > Sent from the R help mailing list archive at Nabble.com. > > ______________________________________________ > R-help at 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.
Instead of rep(drugs, block.size) use rep(list(drugs), block.size) as the argument to expand.grid. Bill Dunlap Spotfire, TIBCO Software wdunlap tibco.com> -----Original Message----- > From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org] On Behalf > Of trekvana > Sent: Wednesday, October 31, 2012 1:18 PM > To: r-help at r-project.org > Subject: [R] expand.grip for permutations > > if i were to have a block size of 4 people and i want to assign a treatment > combination to the entire block, there would be 16 different treatment > combinations (TTTT, TTTP, TTPP, PTTP, etc.) > > i am trying to get all 16 permutations and i am able to use this code below. > > drugs=c('P','T'); > comb=expand.grid(drugs,drugs,drugs,drugs) > > for a block size of 3 the code would be comb=expand.grid(drugs,drugs,drugs) > and for a block size of 2 it would be comb=expand.grid(drugs,drugs). > > my question is whether there is a way to automatically create the comb > variable. i tried using expand.grid(rep(drugs, block.size) but that didn't > work. > > any help on how i can proceed? thanks > > > > -- > View this message in context: http://r.789695.n4.nabble.com/expand-grip-for- > permutations-tp4648067.html > Sent from the R help mailing list archive at Nabble.com. > > ______________________________________________ > R-help at 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.