[R] RWeka and multicore package

[Patrick Connolly]

On Thu, 17-Oct-2013 at 02:21PM -0300, Luís Paulo F. Garcia wrote:

|> I work very mutch with the packages RWeka and multicore. If you try to run
|> J48 or any tree of RWeka with multicore we hava some errors.
|> 
|> Example I:
|> 
|> library(RWeka);
|> library(multicore);
|> 
|> mclapply(1:100, function(i) {
|>     J48(Species ~., iris);
|> });
|> 
|> 
|> Output:  "Error in .jcall(o, \"Ljava/lang/Class;\", \"getClass\") : \n
|> java.lang.ClassFormatError: Incompatible magic value 1347093252 in class
|> file java/lang/ProcessEnvironment$StringEnvironment\n"
|> 
|> 
|> Example II:
|> 
|> library(multicore);
|> 
|> mclapply(1:100, function(i) {
|>     RWeka::J48(Species ~., iris);
|> });
|> 
|> Output: Erro em .jcall(x$classifier, "S", "toString") :
|>   RcallMethod: attempt to call a method of a NULL object.
|> 
|> 
|> Do you know some way to work with parallel processing and RWeka? I tried
|> MPI and SNOW without success.

Not much help, but I too have not been able to get parallelling RWeka
to work.  OTOH, what RWeka can do is very fast compared with, say, gbm
(which does work well with mclapply).  

I suspect that it has something to do with how Java is set up, but I
know nothing about setting up Java.




|> 
|> R version 3.0.2 (2013-09-25) -- "Frisbee Sailing"
|> Ubuntu 12.04 x64
|> 
|> 
|> -- 
|> Lu?s Paulo Faina Garcia
|> Engenheiro de Computa??o - Universidade de S?o Paulo
|> S?o Carlos - SP - Brasil
|> 
|> 	[[alternative HTML version deleted]]
|> 

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|> and provide commented, minimal, self-contained, reproducible code.


-- 
~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.   
   ___    Patrick Connolly   
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