[R] foreach not recognizing functions in memory

[David Winsemius]

On Jul 12, 2011, at 5:28 PM, Bos, Roger wrote:

> All,
>
> I am not understanding the scoping used in foreach when it is used
> inside a function.  I keep getting "could not find function" errors  
> for
> functions that are in memory when I try to use foreach within a  
> function
> call.  I have a simple example below.  "testFun" is in memory and  
> works
> when called by foreach directly, but when I place foreach in a  
> function
> called "helper" and then call helper, foreach cannot find "testFun".
> Can anyone provide a fix?  I hope its just a simple mistake on my part
> and not a limitation of foreach.

I'm wondering if Uwe Ligges' posting in response to what seems like a  
similar question not to long ago may have the answer. Details from the  
header on my reader:

From: 	ligges at statistik.tu-dortmund.de
Subject: 	Re: [R] parallel computing with 'foreach'

Date: 	June 30, 2011 1:24:34 PM EDT

To: 	staceyjeanwood at gmail.com

-- 
david.
>
>> source(.trPaths[5], echo=TRUE, max.deparse.length=150)
>
>> "testFun" <- function(m) {
> +     out <- m*m
> + }
>
>> out <- foreach(m=1:10, .combine=rbind) %dopar% testFun(m)
>
>> "helper" <- function(i) {
> +
> +     out <- foreach(m=1:i, .combine=rbind) %dopar% testFun(m)
> + }
>
>> out <- helper(10)
> Error in testFun(m) : task 1 failed - "could not find function
> "testFun""
>>
>
> Thanks,
>
> Roger
>
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David Winsemius, MD
West Hartford, CT