[R] permutation of rows of a matrix

[Manuel López-Ibáñez]

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
> Canada L8S 4M4
> 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
>>>Canada L8S 4M4
>>>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)?
>>>>
>>>>Thanks for your help,
>>>>
>>>>Jose
>>>>
>>>>______________________________________________
>>>>R-help at stat.math.ethz.ch mailing list
>>>>https://stat.ethz.ch/mailman/listinfo/r-help
>>>>PLEASE do read the posting guide! 
>>>>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
>>>PLEASE do read the posting guide! 
>>>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. 
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>>
>>______________________________________________
>>R-help at stat.math.ethz.ch mailing list
>>https://stat.ethz.ch/mailman/listinfo/r-help
>>PLEASE do read the posting guide! 
>>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