Ralph S.

2008-Jul-19 18:30 UTC

### [R] replicate matrix blocks different numbers of times into new matrix

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! -Ralph _________________________________________________________________ With Windows Live for mobile, your contacts travel with you. 072008

Peter Dalgaard

2008-Jul-19 19:39 UTC

### [R] replicate matrix blocks different numbers of times into new matrix

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 ?ster 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