Hi Talbot,
ma <- matrix(1:6, nrow = 2)
rma <- ma[rep(1:2, c(2,3)),]
Best,
Jim
Talbot Katz wrote:
> Hi.
>
> If I have a vector, v_1, and another vector of positive integers, i_1, the
> same length as v_1, then rep(v_1,i_1) will repeat v_i[j] exactly i_1[j]
> times, like so:
>
>
>>rep(c(1,2,3),c(3,2,1))
>
> [1] 1 1 1 2 2 3
>
>
> I'd like to do the same sort of thing where I replace v_1 with a matrix, and
> the jth row of the matrix is repeated i_1 times.
>
> Obviously, I could do this with for loops, like the following:
>
>
>>(ma1=matrix(1:6,nrow=2))
>
> [,1] [,2] [,3]
> [1,] 1 3 5
> [2,] 2 4 6
>
>>vr1=c(2,3)
>>rma1=NULL
>>for(i in 1:length(vr1)){for(j in 1:vr1[i]){rma1=rbind(rma1,ma1[i,])}}
>>rma1
>
> [,1] [,2] [,3]
> [1,] 1 3 5
> [2,] 1 3 5
> [3,] 2 4 6
> [4,] 2 4 6
> [5,] 2 4 6
>
>
> I just thought some of you clever programmers could show me a more efficient
> way. (I apologize if this question has come up before and you're tired of
> answering it ;-)
>
> Thanks!
>
> -- TMK --
> 212-460-5430 home
> 917-656-5351 cell
>
> ______________________________________________
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> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
--
James W. MacDonald
University of Michigan
Affymetrix and cDNA Microarray Core
1500 E Medical Center Drive
Ann Arbor MI 48109
734-647-5623
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