# [R-sig-Geo] parallelize distance matrix

Vijay Lulla vij@ylull@ @ending from gm@il@com
Wed Aug 22 00:12:03 CEST 2018

```You'll have to do clusterExport(cl, c("ll")) before you call parRapply.
Please see ?`parRapply` and pages 10 and 11 of the parallel::parallel
vignette.
HTH,
Vijay.

On Tue, Aug 21, 2018 at 2:54 PM Roman Luštrik <roman.lustrik using gmail.com>
wrote:

> Cross posted on SO:
>
> https://stackoverflow.com/questions/51952776/parallelization-apply-to-parrapply
>
> On Tue, Aug 21, 2018 at 8:15 PM Ariel Fuentesdi <ariel.fuentesdi using usach.cl>
> wrote:
>
> > Hi, I want to parallelize the calculation of a distance matrix, I've
> tried
> > but I wasn't succesful, this is what I did with a training data.
> >
> > My data set is:
> >
> > ll <- matrix(c(5, 6, 60, 60), ncol=2)
> >
> > And I use the function *spDistsN1* from the library *"sp"* to obtain a
> > distance matrix with *apply*:
> >
> > apply(ll, 1, function(x) spDistsN1(as.matrix(ll), x, longlat = T))
> >
> > But I want to do it with parallelization, so for that:
> >
> > library(parallel)
> > ncore <- detectCores()
> > cl <- makeCluster(ncore)
> > clusterEvalQ(cl = cl, expr = c(library(sp)))
> > parRapply(cl = cl, x = ll, FUN =  function(x) spDistsN1(as.matrix(ll), x,
> > longlat = T))
> >
> > It shows the following error:
> >
> > *Error in checkForRemoteErrors(val) : 4 nodes produced errors; first
> error:
> >
> > How do I fix it?
> > Regards,
> > Ariel Fuentes
> >
> >         [[alternative HTML version deleted]]
> >
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> >
>
>
> --
> In God we trust, all others bring data.
>
>         [[alternative HTML version deleted]]
>
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