[R] create block diagonal with each rows

[arun]

Hi,
May be this helps:
library(Matrix)
res1<-lapply(split(x,1:nrow(x)),function(y) sparseMatrix(i=rep(1:4,each=5),j=1:(4*5),x=y))
 do.call(rbind,lapply(seq_along(res1),function(i) res1[[i]][i,]))
#     [,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8] [,9] [,10] [,11] [,12] [,13] [,14]
#[1,]    1    5    9   13   17    0    0    0    0     0     0     0     0     0
#[2,]    0    0    0    0    0    2    6   10   14    18     0     0     0     0
#[3,]    0    0    0    0    0    0    0    0    0     0     3     7    11    15
#[4,]    0    0    0    0    0    0    0    0    0     0     0     0     0     0
#     [,15] [,16] [,17] [,18] [,19] [,20]
#[1,]     0     0     0     0     0     0
#[2,]     0     0     0     0     0     0
#[3,]    19     0     0     0     0     0
#[4,]     0     4     8    12    16    20

A.K.




----- Original Message -----
From: Kathryn Lord <kathryn.lord2000 at gmail.com>
To: r-help <r-help at r-project.org>
Cc: 
Sent: Wednesday, January 16, 2013 9:11 PM
Subject: [R] create block diagonal with each rows

Dear R users,

I'd like to create a block diagonal matrix with each rows in a matrix.

Here is a simple example. (In fact, the matrix is big)


x <- matrix(1:20, 4,5)

> x
     [,1] [,2] [,3] [,4] [,5]
[1,]    1    5    9   13   17
[2,]    2    6   10   14   18
[3,]    3    7   11   15   19
[4,]    4    8   12   16   20


With each rows in matrix x, I'd like to make the matrix below.


     [,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8] [,9][,10]
[,11][,12][,13][,14][,15][,16][,17][,18][,19][,20]
[1,]    1    5    9   13   17   0    0    0    0    0     0    0    0
0    0     0    0    0    0    0
[2,]    0    0    0    0    0    2    6   10   14   18   0    0    0
0    0     0    0    0    0    0
[3,]    0    0    0    0    0    0    0    0    0    0     3    7   11
15   19   0    0    0    0    0
[4,]    0    0    0    0    0    0    0    0    0    0     0    0    0
0    0     4    8   12   16   20


Any suggestion will be greatly appreciated.

Best,

Kathryn Lord

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