Using snowfall package in R to do some simulation - r

Question

I am staring work with snowfall package in that way:
library(snowfall)
sfInit(parallel=TRUE, cpus=6, type="SOCK")
#loading packages
sfLibrary(package = lars)
sfLibrary(package=covTest)
Function that I want to compute multiple times using sfLapply:
funkcja <- function(i,k=5)
{
beta <- c(k,k,0,k,k,rep(0,35))
X <- matrix(rnorm(100*40),100,40)
Y <- X%*%beta+rnorm(100)
lasso.lars <- lars(X,Y,intercept=FALSE,use.Gram=FALSE)
test <- covTest(lasso.lars,X,Y,sigma.est=1)
test
}
But when I try this
sfLapply(1:100,funkcja)
I get error:
"Error in checkForRemoteErrors(val): 6 nodes produced errors; first error: object 'Y' not found". But when I hide the last but one line and change test for lasso.lars then there is no longer trobule about vector Y:
funkcja <- function(i,k=5)
{
beta <- c(k,k,0,k,k,rep(0,35))
X <- matrix(rnorm(100*40),100,40)
Y <- X%*%beta+rnorm(100)
lasso.lars <- lars(X,Y,intercept=FALSE,use.Gram=FALSE)
#test <- covTest(lasso.lars,X,Y,sigma.est=1)
lasso.lars
}
I dont understand this because the line
test <- covTest(lasso.lars,X,Y,sigma.est=1)
should work since
lars(X,Y,intercept=FALSE,use.Gram=FALSE)
can work. I will be grateful for your help.

Answer 1

My guess is that Y is hiding and internal variable. The following function works (changed the case of "Y" to "y")
funkcja <- function(i,k=5)
{
beta <- c(k,k,0,k,k,rep(0,35))
X <- matrix(rnorm(100*40),100,40)
y <- X %*% beta + rnorm(100)
lasso.lars <- lars(X,y,intercept=FALSE,use.Gram=FALSE)
test <- covTest(lasso.lars,X,y,sigma.est=1)
test
}