[R] parallelized version of "by" and "ave"

[Gabor Grothendieck]

On Mon, Dec 24, 2012 at 1:25 PM, ivo welch <ivo.welch at gmail.com> wrote:
> Dear R experts---
>
> Has anyone written parallel versions of "by" (i.e., mcby) and "ave"
> (i.e. mcave) ?  I did ask a question like this a year ago, and then
> the answer was no.
>
> for those who are googling the group for the answer to this question,
> in the meantime, the poor man's version of "by" is mclapply( split(
> ds, factor ), FUN )
>
> I don't know the poor man's version of "ave".
>

For ave, just parallelize the lapply in this (taken from the ave source):

 split(x, g) <- lapply(spllit(x, g), FUN)

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