[R-sig-Geo] parallelize distance matrix

Ariel Fuentesdi @riel@fuente@di @ending from u@@ch@cl
Tue Aug 21 20:15:08 CEST 2018

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:

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:
object 'll' not found*

How do I fix it?
Ariel Fuentes

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