[R] expand.grid() function
Gavin Simpson
gavin.simpson at ucl.ac.uk
Mon Jun 23 16:21:02 CEST 2008
On Mon, 2008-06-23 at 16:07 +0200, ONKELINX, Thierry wrote:
> Expand.grid works with lists too.
>
> > expand.grid(rep(list(c("u", "l")), 3))
> Var1 Var2 Var3
> 1 u u u
> 2 l u u
> 3 u l u
> 4 l l u
> 5 u u l
> 6 l u l
> 7 u l l
> 8 l l l
Yes, and I got there as well, but then for some reason thought the OP
wanted the result as a character matrix and so went off on a complicated
path to do so. Not sure where I got that from!?
I obviously need more coffee ;-)
G
>
> This is probably as concise as is can get.
>
> 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 Gavin Simpson
> Verzonden: maandag 23 juni 2008 15:51
> Aan: Megh Dal
> CC: r-help at stat.math.ethz.ch
> Onderwerp: Re: [R] expand.grid() function
>
> On Mon, 2008-06-23 at 06:16 -0700, Megh Dal wrote:
> > Hi,
> >
> > I have one question on expand.grid() function.
> >
> > When I write following syntax :expand.grid(c("u", "l"), c("u", "l"),
> > c("u", "l")) I get following as desired :
> > Var1 Var2 Var3
> > 1 u u u
> > 2 l u u
> > 3 u l u
> > 4 l l u
> > 5 u u l
> > 6 l u l
> > 7 u l l
> > 8 l l l
> >
> > However I wanted to write that in more concise manner. Therefore I
> > tried : expand.grid(rep(c("u", "l"), 3)). But I did not get answer
> > that I previously got. Can people here clarify me why it is not like
> > that? Then what would be the mose concise way to do that?
>
> In the first case, you have three vectors of length 2 as arguments to
> expand.grid, but in the second, you have a single vector of length 6. In
> the latter case, expand.grid can't expand a single vector, hence the
> single column result.
>
> This is the closest I got to what you want:
>
> as.matrix(expand.grid(split(rep(c("u","l"), times = 3),
> factor(rep(1:3, each = 2)))))
>
> Which gives:
> > as.matrix(expand.grid(split(rep(c("u","l"), times = 3),
> factor(rep(1:3, each = 2)))))
> 1 2 3
> [1,] "u" "u" "u"
> [2,] "l" "u" "u"
> [3,] "u" "l" "u"
> [4,] "l" "l" "u"
> [5,] "u" "u" "l"
> [6,] "l" "u" "l"
> [7,] "u" "l" "l"
> [8,] "l" "l" "l"
>
> But that isn't particularly concise...
>
> HTH
>
> G
--
%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%
Dr. Gavin Simpson [t] +44 (0)20 7679 0522
ECRC, UCL Geography, [f] +44 (0)20 7679 0565
Pearson Building, [e] gavin.simpsonATNOSPAMucl.ac.uk
Gower Street, London [w] http://www.ucl.ac.uk/~ucfagls/
UK. WC1E 6BT. [w] http://www.freshwaters.org.uk
%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%
More information about the R-help
mailing list