R help - Oct 2007 - Replacing NA values when building matrix using tapply

Hi,

I'm building a matrix m from a data frame d which includes the matrix row,
column and value.

This works well enough:

m <-
tapply(d[,"value"],d[,c("row","column")],c)

However, I'd like to replace any missing values with 0, not NA.  The
obvious doesn't work, however:

m <-
tapply(d[,"value"],d[,c("row","column")],function(x)
{ifelse(is.na(x),0.0,x)})

I can always do this:

m <-
tapply(d[,"value"],d[,c("row","column")],c)
m[is.na(m)] <- 0.0

But it's wasteful to process the table again.  Any ideas?
-- 
Christopher D. Long, San Diego Padres, 100 Park Boulevard, San Diego CA

Score: 0, Diff: 1, clong killed by a Harvard Math Team on  1

Try this:

  xtabs(value ~ row + column, d)[]


On 10/5/07, Chris Long <galizur at gmail.com>
wrote:
> Hi,
>
> I'm building a matrix m from a data frame d which includes the matrix
row,
> column and value.
>
> This works well enough:
>
> m <-
tapply(d[,"value"],d[,c("row","column")],c)
>
> However, I'd like to replace any missing values with 0, not NA.  The
> obvious doesn't work, however:
>
> m <-
tapply(d[,"value"],d[,c("row","column")],function(x)
{ifelse(is.na(x),0.0,x)})
>
> I can always do this:
>
> m <-
tapply(d[,"value"],d[,c("row","column")],c)
> m[is.na(m)] <- 0.0
>
> But it's wasteful to process the table again.  Any ideas?
> --
> Christopher D. Long, San Diego Padres, 100 Park Boulevard, San Diego CA
>
> Score: 0, Diff: 1, clong killed by a Harvard Math Team on  1
>
> ______________________________________________
> R-help at 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.
>

Hello all,



I have a vector with 1000 values and I would like to generate other 
correlated vector, but with different correlation coefficient (for example, 
r = 0.7).

Any ideas how can I do this?



Regards,

Gustavo.


	

	
		
_______________________________________________________ 

Experimente j? e veja as novidades.

Try this:

rnormcor <- function(x,rho) rnorm(1,rho*x,sqrt(1-rho^2))

a <- rnorm(1000,0,1)
b <- sapply(a, rnormcor, rho = 0.7)

cor(a,b)


Joris










                                                                           
             "Gustavo"
             <gugarl1980 at yahoo
             .com.br>                                                   To 
             Sent by:                  <r-help at r-project.org>
             r-help-bounces at r-                                          cc 
             project.org                                                   
                                                                   Subject 
                                       [R] Simulate data based on          
             06/10/2007 04:48          correlation coefficient             
                                                                           
                                                                           
                                                                           
                                                                           
                                                                           
                                                                           




Hello all,



I have a vector with 1000 values and I would like to generate other
correlated vector, but with different correlation coefficient (for example,

r = 0.7).

Any ideas how can I do this?



Regards,

Gustavo.






_______________________________________________________

Experimente j? e veja as novidades.

______________________________________________
R-help at 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.

Similar questions have been asked here before.  See
http://finzi.psych.upenn.edu/R/Rhelp02a/archive/110042.html for one possible
answer (your case will be simpler than this).

-- 
Gregory (Greg) L. Snow Ph.D.
Statistical Data Center
Intermountain Healthcare
greg.snow at intermountainmail.org
(801) 408-8111
 
 
> -----Original Message-----
> From: r-help-bounces at r-project.org 
> [mailto:r-help-bounces at r-project.org] On Behalf Of Gustavo
> Sent: Friday, October 05, 2007 8:48 PM
> To: r-help at r-project.org
> Subject: [R] Simulate data based on correlation coefficient
> 
> Hello all,
> 
> 
> 
> I have a vector with 1000 values and I would like to generate 
> other correlated vector, but with different correlation 
> coefficient (for example, r = 0.7).
> 
> Any ideas how can I do this?
> 
> 
> 
> Regards,
> 
> Gustavo.
> 
> 
> 	
> 
> 	
> 		
> _______________________________________________________ 
> 
> Experimente j? e veja as novidades.
> 
> ______________________________________________
> R-help at 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.
>