R help - Feb 2015 - return named list from foreach

Hello all,

I've been trying to figure out how to return a named list from foreach.  
Given that the order of the returned list is guaranteed to be in the 
order in which the object is passed to foreach, list members can be 
named afterwards.  However, I'm wondering if there's a better way to do 
it, perhaps with some sort of combine function?

    library(doParallel)
    library(foreach)

    cl <- makeCluster(4)
    registerDoParallel(cl)

    df = data.frame(nm = letters[11:20], a = 1:10, b=11:20)

    out = foreach(i=1:nrow(df)) %dopar% {
         a = list(j = sqrt(df[i,]$a), k = sqrt(df[i,]$b))
         a
    }

How do I name the elements of "out" using the corresponding values
df$nm?

thanks,
allie

	[[alternative HTML version deleted]]

You cannot do that in one step. Do it right after:

names(out) <- df$nm

Please don't post using HTML format.. it scrambles code, and since we cannot
see what you saw it doesn't help in any way.

Also note that "df" is a function in the base stats package... not a
good name to use.

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On February 20, 2015 7:44:41 AM PST, Alexander Shenkin <ashenkin at
ufl.edu> wrote:
>Hello all,
>
>I've been trying to figure out how to return a named list from foreach.
> 
>Given that the order of the returned list is guaranteed to be in the 
>order in which the object is passed to foreach, list members can be 
>named afterwards.  However, I'm wondering if there's a better way to
do
>
>it, perhaps with some sort of combine function?
>
>    library(doParallel)
>    library(foreach)
>
>    cl <- makeCluster(4)
>    registerDoParallel(cl)
>
>    df = data.frame(nm = letters[11:20], a = 1:10, b=11:20)
>
>    out = foreach(i=1:nrow(df)) %dopar% {
>         a = list(j = sqrt(df[i,]$a), k = sqrt(df[i,]$b))
>         a
>    }
>
>How do I name the elements of "out" using the corresponding values
>df$nm?
>
>thanks,
>allie
>
>	[[alternative HTML version deleted]]
>
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