[R] Very new help needed.

[Charles C. Berry]

On Thu, 13 Sep 2007, Abu Naser wrote:

>
> Hello all R user,
>
> I am very new with r I have been wondering whether anyone could help me.
> I have a 23000 row and 273 colums. What I want to do is to calculate unit vector for every
> 3 colums along the row. Could you please advise me how to do that using R?


A simple example might help us to understand what it is you want.


Do you wish to convert a 23000 by 273 matrix to a 23000*3 by 273/3 matrix?

If so and your matrix is 'x',

 	dim(x) <- c( 23000*3, 273/3 )

will do.

Do you wish to find the projection of the vector (1,1,1) onto each set of 
x[ i, 1:3 + (j-1)*3 ]? Then

 	apply( array( x, dim=c(23000, 3, 273/3 ) ), c(1,3), mean )

seems like what you would want.

As is stated at the end of your email:

 	PLEASE do read the posting guide
 	http://www.R-project.org/posting-guide.html and provide commented,
 	minimal, self-contained, reproducible code.

This will make it more likely that readers of your message can help you.

>
> with regards,
> Abu
> _________________________________________________________________
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> ______________________________________________
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> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>

Charles C. Berry                            (858) 534-2098
                                             Dept of Family/Preventive Medicine
E mailto:cberry at tajo.ucsd.edu	            UC San Diego
http://famprevmed.ucsd.edu/faculty/cberry/  La Jolla, San Diego 92093-0901