Re: [R] a question on matrix manipulation

[Dimitris Rizopoulos]

Hi Lei,

one way to do this is the following:

mat - matrix(rnorm(4*6), 4, 6)

ind - c(3, 2, 4, 5)
mat[rep(seq_along(ind), ind), ]


I hope it helps.

Best,
Dimitris


Lei Liu wrote:

Hi there,

I have a question on manipulating a matrix. Say I have a matrix A with 3 
rows. I want to generate a new matrix B with 3 duplicates of the first 
row of A, 2 duplicates of the second row, and 4 duplicates of the third 
row. So B is a matrix with 9 rows. Or more general, I want to generate 
(3, 2, 4, 5) duplicates of rows 1-4 of a matrix with 4 rows. Is there a 
simple function to do it? Thanks a lot!


Lei

__
R-help@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.



--
Dimitris Rizopoulos
Assistant Professor
Department of Biostatistics
Erasmus University Medical Center

Address: PO Box 2040, 3000 CA Rotterdam, the Netherlands
Tel: +31/(0)10/7043478
Fax: +31/(0)10/7043014

__
R-help@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.

Re: [R] a question on matrix manipulation

[Simon Blomberg]

How about this:

 mat - matrix(rep(1:4, each=4), nrow=4, byrow=TRUE)
 mat[rep(1:4, times=c(3,2,4,5)),]

Cheers,

Simon.

On Wed, 2009-06-17 at 01:54 -0400, Lei Liu wrote:
 Hi there,
 
 I have a question on manipulating a matrix. Say I have a matrix A 
 with 3 rows. I want to generate a new matrix B with 3 duplicates of 
 the first row of A, 2 duplicates of the second row, and 4 duplicates 
 of the third row. So B is a matrix with 9 rows. Or more general, I 
 want to generate (3, 2, 4, 5) duplicates of rows 1-4 of a matrix with 
 4 rows. Is there a simple function to do it? Thanks a lot!
 
 Lei
 
 __
 R-help@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.
-- 
Simon Blomberg, BSc (Hons), PhD, MAppStat. 
Lecturer and Consultant Statistician 
School of Biological Sciences
The University of Queensland 
St. Lucia Queensland 4072 
Australia
Room 320 Goddard Building (8)
T: +61 7 3365 2506
http://www.uq.edu.au/~uqsblomb
email: S.Blomberg1_at_uq.edu.au

Policies:
1.  I will NOT analyse your data for you.
2.  Your deadline is your problem.

The combination of some data and an aching desire for 
an answer does not ensure that a reasonable answer can 
be extracted from a given body of data. - John Tukey.

__
R-help@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.