Concept

There are two ways to source R script file in RServe Java program. The first way is to directly source it in the java code. The only disadvantage of this method is that each connection would need to do this. As an example consider the following R code

# http://rosettacode.org/wiki/Palindrome_detection#R
###############################################################################
palindrome <- function(p) {
	for(i in 1:floor(nchar(p)/2) ) {
		r <- nchar(p) - i + 1
		if ( substr(p, i, i) != substr(p, r, r) ) return(FALSE) 
	}
	TRUE
}

To source it directly in java

import org.rosuda.REngine.REXP;
import org.rosuda.REngine.REXPMismatchException;
import org.rosuda.REngine.Rserve.RConnection;
import org.rosuda.REngine.Rserve.RserveException;

public class SourcingRFile {
	public static void main(String[] args) throws RserveException,
			REXPMismatchException {
		RConnection c = new RConnection();
		// source the Palindrom function
		c.eval("source(\"[PATH-TO]Palindrome.R\")");

		// call the function. Return true
		REXP is_aba_palindrome = c.eval("palindrome('aba')");
		System.out.println(is_aba_palindrome.asInteger()); // prints 1 => true

		// call the function. return false
		REXP is_abc_palindrome = c.eval("palindrome('abc')");
		System.out.println(is_abc_palindrome.asInteger()); prints 0 => false

	}

}

Another way to source palindrome.R is via the RServe.conf file. The file is present at /etc/Rserve.conf. If the file is not present then create a new one. Add the following line in the Rserve.conf file

source Palindrome.R

If the default file is not used then specify the file on the command line

R CMD Rserve --RS-conf Rserv.conf

The java code remains same except that line 11 in the code above is deleted.

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