cluster/snow question

Many thanks. Yes, weird, somehow ls does not show the variables in the
environment, even though they are clearly there. It would be nice to
understand why that is the case, just to be clear about what is going on.

Thanks Markus,
Tolga




Markus Schmidberger <schmidb at ibe.med.uni-muenchen.de>
10/09/2008 10:45
Please respond to
schmidb at ibe.med.uni-muenchen.de


To
tolga.i.uzuner at jpmorgan.com
cc
r-help at r-project.org
Subject
Re: [R] cluster/snow question






Hi Tolga,

I am not sure why ls() is showing only "args" and "fun".

But x is at the nodes. Try this:

clusterEvalQ(cl,x<-x+3)
[[1]]
[1] 4

[[2]]
[1] 4

clusterCall(cl,function()x+5)
[[1]]
[1] 9

[[2]]
[1] 9

Best
Markus



tolga.i.uzuner at jpmorgan.com schrieb:

Dear R Users,

Apologies for a somewhat basic cluster question. I am trying to come to
grips with how variables are instantiated within the environment of each

node in a cluster. When I run the following code, I expect to see the
variable "x" in the environment of each node, but fail to do so. What am

I

doing wrong ?

library(snow)
noclusters<-2
cl <- makeCluster(noclusters, type = "SOCK")
clusterCall(cl,ls)
x<-1
clusterExport(cl,"x")
clusterCall(cl,ls) #expect to see x in the environment, but get back the

same result as in the call above
stopCluster(cl)

library(snow)
noclusters<-2
cl <- makeCluster(noclusters, type = "SOCK")
clusterCall(cl,ls)

[[1]]
[1] "args" "fun"

[[2]]
[1] "args" "fun"

x<-1
clusterExport(cl,"x")
clusterCall(cl,ls) #expect to see x in the environment

[[1]]
[1] "args" "fun"

[[2]]
[1] "args" "fun"

stopCluster(cl)

Thanks in advance,
Tolga


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