[R] How can I access the list argument within a "for" function call

jim holtman jholtman at gmail.com
Sat Nov 22 16:03:23 CET 2008


I am not sure exactly what you mean with your question.  If you have a
named list and want to access the 'name' within the 'for' along with
the value, then you can do something like this:

for (i in names(myList)){
    value <- myList[[i]]   # get the values
    plot(values, main=paste("Plot of", i))
}

A little more clarification is need on your question.

On Fri, Nov 21, 2008 at 3:30 PM, Mike Rowe <miker at tethysbio.com> wrote:
> Greetings,
>
> I have been playing around with the R/Parallel package, which can farm out the computation of a for-loop among multiple worker processes.  Each worker gets a chunk of the for-loop iterations; for example, if you have two workers and for(x in 1:1000){...}, one worker would typically get iterations 1:500, while the second does 501:1000.
>
> I would like to be able to preallocate matrices to capture the results within the for loop, on the first iteration.  Is there a way to access the list argument of the "for" function programmatically from within the loop?  I am referring to the for arguments shown on page 51 of the R Language Definition manual:
>
>   "for"(var,list,expr)
>
> I think I have a work-around, but was curious whether this was possible...
>
> Thanks,
> Mike
>
>
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>
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-- 
Jim Holtman
Cincinnati, OH
+1 513 646 9390

What is the problem that you are trying to solve?



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