Heroku Buildpack R - rJava Example

.gitignore

MyExchange.class

README.md

See virtualstaticvoid/heroku-buildpack-r#108

javac *.java

heroku create --stack heroku-16

heroku buildpacks:add https://github.com/virtualstaticvoid/heroku-buildpack-r.git#heroku-16

heroku config:set R_VERSION=3.4.3 BUILD_PACK_VERSION=20180110-2010

git push heroku master

heroku run R --no-save -f /app/prog.R

init.R

#
# Example R code to install packages
# See http://cran.r-project.org/doc/manuals/R-admin.html#Installing-packages for details
#

###########################################################
# Update this line with the R packages to install:

my_packages = c("rJava")

###########################################################

install_if_missing = function(p) {
  if (p %in% rownames(installed.packages()) == FALSE) {
    install.packages(p)
  }
  else {
    cat(paste("Skipping already installed package:", p, "\n"))
  }
}
invisible(sapply(my_packages, install_if_missing))

MyExchange.java

//
// This Java program creates a number of variables which will
// then be sent to R to be manipulated.
//
// Example from https://scottdhoover.wordpress.com/2013/03/05/a-basic-rjava-example/
//
public class MyExchange {

    public String getString() {
        return "Testing";
    }

    public String[] getStringArray() {
        return new String[] {"This is just a test...", "string array."};
    }

    public double getdouble() {
        return 10.2;
    }

    public double[] getdoubleArray() {
        return new double[]{0.001, 20.238};
    }

    public double[][] getdoubleMatrix() {
        double[][] doubleMatrix = new double[][]{{1.1,2.2,3.3},{4.4,5.5,6.6}};
        return doubleMatrix;
    }

    public int getInt() {
        return 11;
    }

    public int[] getIntArray() {
        return new int[] {1,2,3,4,5,6};
    }

    public int[][] getIntMatrix() {
        int[][] intMatrix = new int[][]{{1,2,3},{4,5,6}};
        return intMatrix;
    }

    public boolean getboolean() {
        return true;
    }

    public boolean[] getbooleanArray() {
        return new boolean[]{true, true, false, false, true};
    }

    public boolean[][] getbooleanMatrix() {
        boolean[][] booleanMatrix = new boolean[][]{{true, true, false},{false, true, true}};
        return booleanMatrix;
    }

    public static void main(String[] args) {

    }
}

prog.R

#
# Example R program
#

# example from https://scottdhoover.wordpress.com/2013/03/05/a-basic-rjava-example/

library('rJava')

.jinit()
.jaddClassPath("/app")
.jclassPath()

myExchange <- .jnew("MyExchange")

# strings #
stringTest <- .jcall(myExchange, "S", "getString")
stringArrayTest <- .jcall(myExchange, "[S", "getStringArray")
stringTest; stringArrayTest

# doubles #
doubleTest <- .jcall(myExchange, "D", "getdouble")
doubleArrayTest <- .jcall(myExchange, "[D", "getdoubleArray")
doubleMatrixTest <- .jcall(myExchange, "[[D", "getdoubleMatrix", simplify=T)
doubleTest; doubleArrayTest; doubleMatrixTest

# integers #
intTest <- .jcall(myExchange, "I", "getInt")
intArrayTest <- .jcall(myExchange, "[I", "getIntArray")
intMatrixTest <- .jcall(myExchange, "[[I", "getIntMatrix", simplify=T)
intTest; intArrayTest; intMatrixTest

# boolean #
booleanTest <- .jcall(myExchange, "Z", "getboolean")
booleanArrayTest <- .jcall(myExchange, "[Z", "getbooleanArray")
booleanMatrixTest <- .jcall(myExchange, "[[Z", "getbooleanMatrix", simplify=T)
booleanTest; booleanArrayTest; booleanMatrixTest