[R] parallel processing with multiple directories

[Martin Morgan]

On 04/17/2012 11:06 AM, David Schaefer wrote:
> Hello,
>
> I would like to run some code in parallel with each cluster reading/writing to a different working directory.  I've tried the following code without success. The error I get is: "Error in setwd(x) : cannot change working directory"
>
> library(parallel)
> dirs<- list("out1","out2","out3")   # these directories are located within the current working directory
> temp<- 1:3
> testF<- function(x) {
>    setwd(x)
>    saveRDS(temp,"temp.drs")
>    }
> mclapply(dirs, testF)
>
> Any help would be appreciated!

Hi David,

Suppose that jobs 1 and 3 are executed on processor 2. Then after the 
first iteration the directory is ./out1 and on the second iteration 
setwd() tries to change to ./out1/out3. Full path names might help.

My unasked-for advice would be to put 'more' of the processing in testF, 
so that it is reasonable to return and then aggregate the results 
without writing to disk.

Martin

>
> --David
>
> *********************************************
> David R. Schaefer, Ph.D.
> Assistant Professor
> School of Social and Family Dynamics
> Arizona State University
> www.public.asu.edu/~schaef/
>
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