[R] How to capture console output in a numeric format

[William Dunlap]

Try using dput(f) instead of print(f) and
use eval(parse(text=capture.output(...))).

I would tend to use something like
   OUTPUTS <- list()
   fr <- function(x) {
       on.exit(OUTPUTS[[length(OUTPUTS)+1]] <<- list(x=x,f=f))
       ... compute and return f
   }
so you don't have to use capture.output.
(You can use trace() to automate this sort
of thing.)

Bill Dunlap
Spotfire, TIBCO Software
wdunlap tibco.com  

> -----Original Message-----
> From: r-help-bounces at r-project.org 
> [mailto:r-help-bounces at r-project.org] On Behalf Of Ravi Varadhan
> Sent: Friday, June 24, 2011 7:40 AM
> To: r-help at r-project.org
> Subject: [R] How to capture console output in a numeric format
> 
> Hi,
> 
> I would like to know how to capture the console output from 
> running an algorithm for further analysis.  I can capture 
> this using capture.output() but that yields a character 
> vector.  I would like to extract the actual numeric values.  
> Here is an example of what I am trying to do.
> 
> fr <- function(x) {   ## Rosenbrock Banana function
>     on.exit(print(f))
>     x1 <- x[1]
>     x2 <- x[2]
>     f <- 100 * (x2 - x1 * x1)^2 + (1 - x1)^2
>     f
> }
> 
> fvals <- capture.output(ans <- optim(c(-1.2,1), fr))
> 
> Now, `fvals' contains character elements, but I would like to 
> obtain the actual numerical values.  How can I do this?
> 
> Thanks very much for any suggestions.
> 
> Best,
> Ravi.
> 
> -------------------------------------------------------
> Ravi Varadhan, Ph.D.
> Assistant Professor,
> Division of Geriatric Medicine and Gerontology School of 
> Medicine Johns Hopkins University
> 
> Ph. (410) 502-2619
> email: rvaradhan at jhmi.edu<mailto:rvaradhan at jhmi.edu>
> 
> 
> 	[[alternative HTML version deleted]]
> 
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