I would appreciate any suggestions on which function to use to write subsequent functions analysing combinations of treatments. This refers to experimental trials of medical treatments. I want to write routines to analyse various comparisons (combinations) So .... if 5 treatments are available (t01, t02, t03, t04 and t05) I want to write a general routine that works out all possible combinations, without repeats. The other complication is that I want to be able to designate any one of the treatments as the common comparator such that all other treatments are compared to it. For example, if I designate t04 as the common comparator then I want it to give me back some sort of vector or matrix with results t01, t04 t02, t04 t03, t04 t05, t04 In my research I've found functions such as combinations and permutations in gtools, and also choose(). I suspect these could be coerced to provide the correct output but I may be missing a specific, or more flexible package that will produce this. Any suggestions most welcome. Thanks Jim ==============================Dr. Jim Maas University of East Anglia Norwich, UK [[alternative HTML version deleted]]
one possibility is:
treats <- t(combn(c("t01", "t02", "t03",
"t04", "t05"), 2))
treats
# extract only t04
treats[apply(treats == "t04", 1, any), ]
I hope it helps.
Best,
Dimitris
On 8/18/2010 1:44 PM, Maas James Dr (MED) wrote:> I would appreciate any suggestions on which function to use to write
subsequent functions analysing combinations of treatments.
>
> This refers to experimental trials of medical treatments. I want to write
routines to analyse various comparisons (combinations)
>
> So .... if 5 treatments are available (t01, t02, t03, t04 and t05) I want
to write a general routine that works out all possible combinations, without
repeats. The other complication is that I want to be able to designate any one
of the treatments as the common comparator such that all other treatments are
compared to it.
>
> For example, if I designate t04 as the common comparator then I want it to
give me back some sort of vector or matrix with results
>
> t01, t04
> t02, t04
> t03, t04
> t05, t04
>
> In my research I've found functions such as combinations and
permutations in gtools, and also choose(). I suspect these could be coerced to
provide the correct output but I may be missing a specific, or more flexible
package that will produce this.
>
> Any suggestions most welcome.
>
> Thanks
>
> Jim
>
> ==============================> Dr. Jim Maas
> University of East Anglia
> Norwich, UK
>
> [[alternative HTML version deleted]]
>
> ______________________________________________
> 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.
>
--
Dimitris Rizopoulos
Assistant Professor
Department of Biostatistics
Erasmus University Medical Center
Address: PO Box 2040, 3000 CA Rotterdam, the Netherlands
Tel: +31/(0)10/7043478
Fax: +31/(0)10/7043014
Hi Jim, How about expand.grid()?> expand.grid(c('t01','t02','t03','t04','t05'), 't04')Var1 Var2 1 t01 t04 2 t02 t04 3 t03 t04 4 t04 t04 5 t05 t04> expand.grid(c('t01','t02','t03','t04','t05'), 't01')Var1 Var2 1 t01 t01 2 t02 t01 3 t03 t01 4 t04 t01 5 t05 t01 HTH, Jorge On Wed, Aug 18, 2010 at 7:44 AM, Maas James Dr (MED) <> wrote:> I would appreciate any suggestions on which function to use to write > subsequent functions analysing combinations of treatments. > > This refers to experimental trials of medical treatments. I want to write > routines to analyse various comparisons (combinations) > > So .... if 5 treatments are available (t01, t02, t03, t04 and t05) I want > to write a general routine that works out all possible combinations, without > repeats. The other complication is that I want to be able to designate any > one of the treatments as the common comparator such that all other > treatments are compared to it. > > For example, if I designate t04 as the common comparator then I want it to > give me back some sort of vector or matrix with results > > t01, t04 > t02, t04 > t03, t04 > t05, t04 > > In my research I've found functions such as combinations and permutations > in gtools, and also choose(). I suspect these could be coerced to provide > the correct output but I may be missing a specific, or more flexible package > that will produce this. > > Any suggestions most welcome. > > Thanks > > Jim > > ==============================> Dr. Jim Maas > University of East Anglia > Norwich, UK > > [[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. >[[alternative HTML version deleted]]