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
>
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>
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