# [R] permutation of rows of a matrix

Manuel López-Ibáñez manuellopezibanez at yahoo.es
Sun Apr 16 11:51:58 CEST 2006

```Dear John,

I understand what you mean. However, when someone is learning R for the
first time or have little experience, such examples help to understand
the connection of different parts of the language.

Moreover, things that make sense once you know them, can be difficult to
relate in the first place. For example, it would be interesting to know
how many new R users don't know that there is a manual page for "[".

I hope you can understand my point of view (you may disagree, though.)

Regards,
Manuel.

John Fox wrote:
> Dear Manuel,
>
> Although ?sample doesn't specifically describe permuting the rows of a
> matrix, it does say that "sample(x) generates a random permutation of the
> elements of x (or 1:x)." Indexing the rows of the matrix by a permutation of
> 1:x (where x is the number of rows) doesn't seem to be much of a leap.
>
> Regards,
>  John
>
> --------------------------------
> John Fox
> Department of Sociology
> McMaster University
> Hamilton, Ontario
> 905-525-9140x23604
> http://socserv.mcmaster.ca/jfox
> --------------------------------
>
>
>>-----Original Message-----
>>From: r-help-bounces at stat.math.ethz.ch
>>[mailto:r-help-bounces at stat.math.ethz.ch] On Behalf Of Manuel
>>López-Ibáñez
>>Sent: Saturday, April 15, 2006 9:44 AM
>>To: r-help at stat.math.ethz.ch
>>Subject: Re: [R] permutation of rows of a matrix
>>
>>help(sample) does not say anything about randomly permuting
>>the rows of a matrix M by using M[sample(m,m),]. Perhaps it
>>could be added as an example of use.
>>
>>John Fox wrote:
>>
>>>Dear Jose,
>>>
>>>M[sample(m, m),] will randomly permute the rows of M. [You probably
>>>could have figured this out via help.search("permutation"), which
>>>would have led you to sample().]
>>>
>>>Regards,
>>> John
>>>
>>>--------------------------------
>>>John Fox
>>>Department of Sociology
>>>McMaster University
>>>Hamilton, Ontario
>>>905-525-9140x23604
>>>http://socserv.mcmaster.ca/jfox
>>>--------------------------------
>>>
>>>
>>>
>>>>-----Original Message-----
>>>>From: r-help-bounces at stat.math.ethz.ch
>>>>[mailto:r-help-bounces at stat.math.ethz.ch] On Behalf Of javargas
>>>>Sent: Saturday, April 15, 2006 7:53 AM
>>>>To: r-help at stat.math.ethz.ch
>>>>Subject: [R] permutation of rows of a matrix
>>>>
>>>>How can I generate a random permutation between rows of a
>>
>>matrix M (of
>>
>>>>m rows and n columns)?
>>>>
>>>>
>>>>Jose
>>>>
>>>>______________________________________________
>>>>R-help at stat.math.ethz.ch mailing list
>>>>https://stat.ethz.ch/mailman/listinfo/r-help
>>>>http://www.R-project.org/posting-guide.html
>>>
>>>
>>>______________________________________________
>>>R-help at stat.math.ethz.ch mailing list
>>>https://stat.ethz.ch/mailman/listinfo/r-help
>>>http://www.R-project.org/posting-guide.html
>>>
>>
>>
>>______________________________________________
>>LLama Gratis a cualquier PC del Mundo.
>>Llamadas a fijos y móviles desde 1 céntimo por minuto.
>>http://es.voice.yahoo.com
>>
>>______________________________________________
>>R-help at stat.math.ethz.ch mailing list
>>https://stat.ethz.ch/mailman/listinfo/r-help
>>http://www.R-project.org/posting-guide.html
>
>
>

______________________________________________
LLama Gratis a cualquier PC del Mundo.
Llamadas a fijos y móviles desde 1 céntimo por minuto.
http://es.voice.yahoo.com

```