From: Darcy Webber <darcy.webber_at_gmail.com>

Date: Wed, 02 Mar 2011 10:55:27 +1300

R-help_at_r-project.org mailing list

https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code. Received on Tue 01 Mar 2011 - 22:23:10 GMT

Date: Wed, 02 Mar 2011 10:55:27 +1300

a <- matrix(1:32, nrow = 4, ncol = 8)

a

[,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8]

*[1,] 1 5 9 13 17 21 25 29
**[2,] 2 6 10 14 18 22 26 30
*

[3,] 3 7 11 15 19 23 27 31

[4,] 4 8 12 16 20 24 28 32

I would like it to look like the following matrix:

[,1] [,2] [,3] [,4]

[1,] 1 5 9 13

*[2,] 2 6 10 14
**[3,] 3 7 11 15
**[4,] 4 8 12 16
**[5,] 17 21 25 29
**[6,] 18 22 26 30
**[7,] 19 23 27 31
**[8,] 20 24 28 32
*

I can achieve this using the following:

a1 <- a[, 1:4]

a2 <- a[, 5:8]

b <- rbind(a1, a2)

However, my initial matrix often has a varibale number of columns (in multiples of 4, and I still want to split the columns into blocks of 4 and stack these). I have considered working out how many blocks the matrix must be split into using: no.blocks <- ncol(a)/4. My problem is then implementing this information to actually split the matrix up and then stack it. Any guidance on this would be much appreciated.

Regards

Darcy Webber

R-help_at_r-project.org mailing list

https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code. Received on Tue 01 Mar 2011 - 22:23:10 GMT

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