[R] Package gamlss used inside foreach() and %dopar% fails to find an object

[Jeff Newmiller]

If the code you are running in parallel is complicated, maybe foreach is not sophisticated enough to find all the variables you refer to. Maybe use parallel::clusterExport yourself? But be a aware that passing parameters is much safer than directly accessing globals in parallel processing, so this might just be your warning to not do that anyway. 
-- 
Sent from my phone. Please excuse my brevity.

On March 9, 2018 7:50:44 AM PST, Nik Tuzov <ntuzov at beacon.partek.com> wrote:
>
>Hello all:
>
>Please help me with this "can't find object" issue. I'm trying to get
>leave-one-out predicted values for Beta-binomial regression.  
>It may be the gamlss issue because the code seems to work when %do% is
>used. I have searched for similar issues, but haven't managed to figure
>it out. This is on Windows 10 platform.
>
>Thanks in advance,
>Nik
>
># --------------------------------------------------------------
>
>library('gamlss')
>library('foreach')
>library('doParallel')
>
>registerDoParallel(cores = 4)
># Generate data
>set.seed(314)
>sample.size <- 30
>input.processed.cut <- data.frame(TP = round(runif(sample.size) * 100),
>
>                                 FP = round(runif(sample.size) * 100), 
>                                  x = runif(sample.size))
># Fit Beta-binomial
>model3 <- gamlss(formula = cbind(TP, FP) ~ x,   
>                 family = BB,  
>                 data = input.processed.cut) 
>
># Get the leave-one-out values
>loo_predict.mu <- function(model.obj, input.data) {
>yhat <- foreach(i = 1 : nrow(input.data), .packages="gamlss", .combine
>= rbind) %dopar% {
>    updated.model.obj <- update(model.obj, data = input.data[-i, ])
>predict(updated.model.obj, what = "mu", newdata = input.data[i,], type
>= "response")
>  }
>  return(data.frame(result = yhat[, 1], row.names = NULL))
>}
>
>par.run <- loo_predict.mu(model3, input.processed.cut)
>
># Error in { : task 1 failed - "object 'input.data' not found" 
>
>#
>------------------------------------------------------------------------
>
>> version
>               _                           
>platform       x86_64-w64-mingw32          
>arch           x86_64                      
>os             mingw32                     
>system         x86_64, mingw32             
>status                                     
>major          3                           
>minor          4.3                         
>year           2017                        
>month          11                          
>day            30                          
>svn rev        73796                       
>language       R                           
>version.string R version 3.4.3 (2017-11-30)
>nickname       Kite-Eating Tree
>
>______________________________________________
>R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see
>https://stat.ethz.ch/mailman/listinfo/r-help
>PLEASE do read the posting guide
>http://www.R-project.org/posting-guide.html
>and provide commented, minimal, self-contained, reproducible code.