Need to pass Arraylist from java program to R script as a parameter

Question

I have simple java program which reads data from csv file and validate the data then call the R script to calculate the average of list of values, i'm using Renjin to call R program. I am able to call R script without passing parameter but here i need to pass list of values to my R script.

Here is my java code:

// listofval --list of float values example listofval= [3.3,5.2,6,9]

RenjinScriptEngineFactory factory = new RenjinScriptEngineFactory();
ScriptEngine engine = factory.getScriptEngine();
engine.put("input",listofval);
engine.eval(new java.io.FileReader("avg.R"));

Here is my Rscript:

args=(commandArgs(TRUE))
args <- eval(parse(text=args[1]))
input <- args
customMean <- function(vector) {
mean(vector)
}
result.mean<- customMean(input)
print(result.mean)

I'm looking for work around, Can someone please help me on this?

Thanks in advance.

Ahmet Eroğlu · Accepted Answer · 2021-01-12 12:33:00Z

0

You can try passing arguments to your engine using sessions in java.

Please customize and/or try the following logic.

Session session = new SessionBuilder()
.withDefaultPackages()
.build();

session.setCommandLineArguments("/usr/bin/renjin", "X", "Y", "--args", "Z");

RenjinScriptEngineFactory factory = new RenjinScriptEngineFactory();
RenjinScriptEngine engine = factory.getScriptEngine(session);

engine.eval("print(commandArgs(trailingOnly = FALSE))"); 
engine.eval("print(commandArgs(trailingOnly = TRUE))");

answered Jan 12, 2021 at 12:33

Ahmet Eroğlu

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1 Comment

Darshan Mahalinge Gowda Over a year ago

Hi Ahmet Eroğlu , thanks for your answer, I tried this approach Script is running but its not taking the argument.

Darshan Mahalinge Gowda · Accepted Answer · 2021-01-13 11:52:19Z

0

I was able to resolve my issue, hope it could help someone! In R script we need to remove below line so that program is not expecting command line argument.

args=(commandArgs(TRUE))    
args <- eval(parse(text=args[1]))
input <- args

In java program i have saved my argument as input, in R environment it will be accessed as input

engine.put("input",listofval);

Final Rscript:

customMean <- function(vector) {
 return mean(vector)
}
result.mean<- customMean(input)

answered Jan 13, 2021 at 11:52

Darshan Mahalinge Gowda

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