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R Programming Complete Tutorial

rJava: Low-Level R to Java Interface

Modern programming languages that are mainly used to develop enterprise software systems include Java. These platforms have rich functionality to write business logic. However, they are not much efficient when it comes to statistical or mathematical modeling. In the field of modeling, the major contributors are R, Weka, Octave, etc. Out of these, most work as simulation environments; however, R could be used both for simulation as well as for production-level systems. From the above discussion, it is clear that intelligence-based software could not be developed just by using a single technology. To overcome this obstacle, a combination of technologies should be applied. The figure below shows a high-level view of such an intelligent software system and where each technology fits.

            

From the figure, it is clear that a hybrid system has to be created. In the current scenario, the hybrid system consists of JAVA for business logic programming and R for statistical programming. This shows that we have a need to integrate R with Java. In the following text, we will be showing how to integrate R with Java using rJava library.

1. Install Java
To start, we need Java. We can download the Java Runtime Environment (JRE) and Java Development Kit (JDK). After properly installation of Java we can check executing the
command:

2. Configure Java Parameters for R

3. R provides thejavareconf utility to configure Java support in R.  To prepare the R environment for Java; we can execute this command:

4. Install rJava Package
We can obtain rJava release versions from CRAN. If an Internet connection is available, it will be installed by the command install.packages in an R session.

5. Configure the Environment Variable CLASSPATH

TheCLASSPATH environment variable must contain the directories with the jar and class files.  The class files in this example will be created in /usr/lib/Java/java_1.8.0_77.