[R] replicate matrix blocks different numbers of times into new matrix
Peter Dalgaard
p.dalgaard at biostat.ku.dk
Sat Jul 19 21:39:25 CEST 2008
Ralph S. wrote:
> Hi,
>
> I am trying to replicate blocks of a matrix (defined by factors) into another matrix, but an unequal, consecutive number of times for each factor.
>
> I need to find an elegant and fast way to do this, so loops will not work.
>
> An example of what I am trying to do is the following:
>
> # the data - first column entries are both data and the two factors
> x<-matrix(c(1,2,3,4),2,2)
>
>> x
>>
> [,1] [,2]
> [1,] 1 3
> [2,] 2 4
>
> # the number of repetitions of the first and second factor
> n<-c(1,3)
>
> This is what I want as output:
>
> [,1] [,2]
> [1,] 1 3
> [2,] 2 4
> [3,] 2 4
> [4,] 2 4
>
>
> Any ideas how to get there? I have tried using tapply with combination of rep, but this does not work (I need 1 and then 3 replications).
>
> Any help would be great!
>
Will this do?
x[rep(1:2,n),]
--
O__ ---- Peter Dalgaard Øster Farimagsgade 5, Entr.B
c/ /'_ --- Dept. of Biostatistics PO Box 2099, 1014 Cph. K
(*) \(*) -- University of Copenhagen Denmark Ph: (+45) 35327918
~~~~~~~~~~ - (p.dalgaard at biostat.ku.dk) FAX: (+45) 35327907
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