[R-sig-Geo] Repeat columns and rows of matrix

[Roger Bivand]

If this question is related to an earlier one (LM tests for spatial panel 
data), I don't think that the correct expansion of W for T=2 is:

W W
W W

but rather

W 0
0 W

so a Kronecker product of W and diag(T). Here the output is sparse, and 
with T=9 and N=1K, this may be important, especially if W is sparse too. 
However, we don't know. So for now we need

M <- matrix(1, nrow=9, ncol=9)
W9 <- kronecker(W, M)

which answers the apparent question. However, I don't think that it was 
the intention.

Roger

On Fri, 9 May 2014, Jean-Daniel Sylvain wrote:

> Hi,
>
> You hould use the apply function function, which will apply the function 
> rep() on one of the dimension of your matrix (1 for row, and 2 for columns).
>
> mat <- matrix(data=1:100,10,10)
>
> apply(mat,MARGIN=1,function(x) rep(x,10))
> apply(mat,MARGIN=2,function(x) rep(x,10))
>
> Hope this helps,
>
> JD
>
> Le 5/9/2014 7:33 AM, az14 a écrit :
>> Dear list,
>> i have a matrixW(1060*1060), i want to repeat each column and row 9 times,
>> such as to have a new matrix W1(9540*9540).
>> I use the code:
>> rep.row<-function(x,n){
>>     matrix(rep(x,each=n),nrow=n)
>> }
>> rep.col<-function(x,n){
>>     matrix(rep(x,each=n), ncol=n, byrow=TRUE)
>> }
>> 
>> ww<-rep.row(w,9)
>> W1<-rep.col(ww,9)
>> 
>> but i did not work!
>> 
>> Is there another way to do it ?
>> 
>> Any help would me appreciated.
>> Thank YOU.
>> 
>> 
>> 
>> --
>> View this message in context: 
>> http://r-sig-geo.2731867.n2.nabble.com/Repeat-columns-and-rows-of-matrix-tp7586408.html
>> Sent from the R-sig-geo mailing list archive at Nabble.com.
>> 
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-- 
Roger Bivand
Department of Economics, Norwegian School of Economics,
Helleveien 30, N-5045 Bergen, Norway.
voice: +47 55 95 93 55; fax +47 55 95 91 00
e-mail: Roger.Bivand at nhh.no