Re: [R] help with vector construction

2007-07-05 Thread Greg Snow
One approach is to use the fact that vectors are automatically
replicated to the correct length when subscripting, so you can do
something like:

> my.matrix[ c(FALSE,TRUE,FALSE), 3 ] 

To get every 3rd element starting at the 2nd element, and the 3rd
column.

Hope this helps,


-- 
Gregory (Greg) L. Snow Ph.D.
Statistical Data Center
Intermountain Healthcare
[EMAIL PROTECTED]
(801) 408-8111
 
 

> -Original Message-
> From: [EMAIL PROTECTED] 
> [mailto:[EMAIL PROTECTED] On Behalf Of Juan 
> Pablo Fededa
> Sent: Thursday, July 05, 2007 11:30 AM
> To: r-help@stat.math.ethz.ch
> Subject: [R] help with vector construction
> 
> Hi all,
> 
> I want to make a vector with the third column of a matrix, 
> but only for the
> 2+3n rows of the matrix, with n being an entire number from 0 
> to a million.
> How can I do that in an easy way?
> Thanks in advance,
> 
> Juan Pablo
> 
>   [[alternative HTML version deleted]]
> 
> __
> R-help@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
> and provide commented, minimal, self-contained, reproducible code.
>

__
R-help@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
and provide commented, minimal, self-contained, reproducible code.


Re: [R] help with vector construction

2007-07-05 Thread John Kane
Or an alternative to Henrique's if you want to select
all the rows from row 2 up to the  3*n row this may
work.

 n  <- 2
 myvector <- data1[2:(2*n), 3]


--- Juan Pablo Fededa <[EMAIL PROTECTED]> wrote:

> Hi all,
> 
> I want to make a vector with the third column of a
> matrix, but only for the
> 2+3n rows of the matrix, with n being an entire
> number from 0 to a million.
> How can I do that in an easy way?
> Thanks in advance,
> 
> Juan Pablo
> 
>   [[alternative HTML version deleted]]
> 
> __
> R-help@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
> and provide commented, minimal, self-contained,
> reproducible code.
>

__
R-help@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
and provide commented, minimal, self-contained, reproducible code.


Re: [R] help with vector construction

2007-07-05 Thread Henrique Dallazuanna
Hi,

Example:

n <- 1:10
mat[2+3*n,3] #Where mat is the matrix

Is what you want?
-- 
Henrique Dallazuanna
Curitiba-Paraná-Brasil
25° 25' 40" S 49° 16' 22" O

On 05/07/07, Juan Pablo Fededa <[EMAIL PROTECTED]> wrote:
>
> Hi all,
>
> I want to make a vector with the third column of a matrix, but only for
> the
> 2+3n rows of the matrix, with n being an entire number from 0 to a
> million.
> How can I do that in an easy way?
> Thanks in advance,
>
> Juan Pablo
>
> [[alternative HTML version deleted]]
>
> __
> R-help@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
> and provide commented, minimal, self-contained, reproducible code.
>

[[alternative HTML version deleted]]

__
R-help@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
and provide commented, minimal, self-contained, reproducible code.


[R] help with vector construction

2007-07-05 Thread Juan Pablo Fededa
Hi all,

I want to make a vector with the third column of a matrix, but only for the
2+3n rows of the matrix, with n being an entire number from 0 to a million.
How can I do that in an easy way?
Thanks in advance,

Juan Pablo

[[alternative HTML version deleted]]

__
R-help@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
and provide commented, minimal, self-contained, reproducible code.