[R] undefined S4 class in parallel computing at snowfall

[Edwin Sun]

Dear All,

I have a question of how to export S4 class specification to
clusters/workers in parallel computing. The package I used is snowfall. The
problem is reproducible as follows. Any hint is greatly appreciated.

Edwin Sun

=== begin ===========
library(snowfall)
sfInit(parallel = TRUE, cpus = 2)
setClass("catt", representation(aa = "numeric"))
setClass("dogg", representation(bb = 'character', cc = "catt"))
f1 <- function(y1) { new('catt', aa = y1 + 1) }
f3 <- function(y2, y3) { new('dogg', bb=c(y2, 'GA'), cc = f1(y3)) }
dat <- 1:5
f1(dat)
f3('NY', dat)     
sapply(c("state1", 'state2', 'state3'), f3, dat) 
sfExportAll()
sfClusterEval(ls())
sfSapply(c("s1", 's2', 's3'), f3, dat) 
sfStop() 

# sfSapply generates the following error
#    Error in checkForRemoteErrors(val) : 
#      2 nodes produced errors; first error: "dogg" is not a defined class
=== end =============

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