Dear list, I have a vector of elements which I want to combined each with each, but none with itself. For example,> v <- c("a", "b", "c")and I need a function 'combine' such that> combine(v)[[1]] [1] "a" "b" [[2]] [1] "a" "b" [[3]] [1] "b" "c" I am not very interested in the orders of the output items for now, and the form can be something differs from list, like matrix or data frame. I know of 'expand.grid', but it will combine each item with each item including itself, so not what I wants. Could you help me please. Thank you. Mvh., Marie [[alternative HTML version deleted]]
Dear Marie, Try this: combn(v,2,list) HTH, Jorge On Mon, Jun 8, 2009 at 8:56 AM, Marie Sivertsen <mariesivert@gmail.com>wrote:> Dear list, > > I have a vector of elements which I want to combined each with each, but > none with itself. For example, > > > v <- c("a", "b", "c") > > and I need a function 'combine' such that > > > combine(v) > [[1]] > [1] "a" "b" > > [[2]] > [1] "a" "b" > > [[3]] > [1] "b" "c" > > I am not very interested in the orders of the output items for now, and the > form can be something differs from list, like matrix or data frame. I know > of 'expand.grid', but it will combine each item with each item including > itself, so not what I wants. > > Could you help me please. Thank you. > > Mvh., > Marie > > [[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]]
one way is:
combn(c("a", "b", "c"), 2)
I hope it helps.
Best,
Dimitris
Marie Sivertsen wrote:> Dear list,
>
> I have a vector of elements which I want to combined each with each, but
> none with itself. For example,
>
>> v <- c("a", "b", "c")
>
> and I need a function 'combine' such that
>
>> combine(v)
> [[1]]
> [1] "a" "b"
>
> [[2]]
> [1] "a" "b"
>
> [[3]]
> [1] "b" "c"
>
> I am not very interested in the orders of the output items for now, and the
> form can be something differs from list, like matrix or data frame. I know
> of 'expand.grid', but it will combine each item with each item
including
> itself, so not what I wants.
>
> Could you help me please. Thank you.
>
> Mvh.,
> Marie
>
> [[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
Marie Sivertsen wrote:> Dear list, > > I have a vector of elements which I want to combined each with each, but > none with itself. For example, > > >> v <- c("a", "b", "c") >> > > and I need a function 'combine' such that > > >> combine(v) >> > [[1]] > [1] "a" "b" > > [[2]] > [1] "a" "b" > > [[3]] > [1] "b" "c" > > I am not very interested in the orders of the output items for now, and the > form can be something differs from list, like matrix or data frame. I know > of 'expand.grid', but it will combine each item with each item including > itself, so not what I wants. > > Could you help me please. Thank you. > > Mvh., > Marie > > [[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. >I guess you actually want, [[1]] [1] "a" "b" [[2]] [1] "a" "c" # not "a" "b" again [[3]] [1] "b" "c" if so, try ?combn > combn(v,2) [,1] [,2] [,3] [1,] "a" "a" "b" [2,] "b" "c" "c" HTH, baptiste -- _____________________________ Baptiste Augui? School of Physics University of Exeter Stocker Road, Exeter, Devon, EX4 4QL, UK Phone: +44 1392 264187 http://newton.ex.ac.uk/research/emag