frequency table

RSample.java

package rJava;

import java.util.Vector;

import org.rosuda.JRI.REXP;
import org.rosuda.JRI.RVector;
import org.rosuda.JRI.Rengine;

public class RSample {
	public static void main(String[] args) {
		System.out.println("R_HOME:" + System.getenv("R_HOME"));
		System.out.println("java.library.path:"
				+ System.getProperty("java.library.path"));

		Rengine engine = new Rengine(new String[] {
			"--no-save"
		}, false, null);

		try {
			int n = 1000000;
			int m = 10;
			double r = 6.0;
			double[] x = new double[n];
			for (int i = 0; i < n; i++) {
				x[i] = 0.0;
				for (int j = 0; j < m; j++) {
					x[i] += Math.random() * r;
				}
			}
			double[] b = new double[m + 1];
			for (int i = 0; i < m + 1; i++) {
				b[i] = r * i;
			}
			engine.assign("x", x);
			engine.assign("b", b);
			engine.eval("x2<-cut(x, breaks=b, right=FALSE, ordered_result=TRUE)");
			engine.eval("x3<-table(x2)");
			REXP result = engine.eval("as.data.frame(rbind(x3, x3/sum(x3)))");

			RVector resultV = result.asVector();
			@SuppressWarnings("unchecked")
			Vector<String> labels = (Vector<String>) resultV.getNames();
			for (String label : labels) {
				double[] v = resultV.at(label).asDoubleArray();
				String out = "label=" + label;
				out += "\tfreq=" + v[0];
				out += "\tratio=" + v[1];
				System.out.println(out);
			}

			String[] sigma1 = {
					"[24,30)", "[30,36)"
			};
			System.out.println("sigma1=" + func(resultV, sigma1));
			String[] sigma2 = {
					"[18,24)", "[24,30)", "[30,36)", "[36,42)"
			};
			System.out.println("sigma2=" + func(resultV, sigma2));
			String[] sigma3 = {
					"[12,18)", "[18,24)", "[24,30)", "[30,36)", "[36,42)",
					"[42,48)"
			};
			System.out.println("sigma3=" + func(resultV, sigma3));
		} finally {
			engine.end();
		}
	}

	private static double func(RVector resultV, String[] labels) {
		double ratio = 0.0;
		for (String label : labels) {
			ratio += resultV.at(label).asDoubleArray()[1];
		}
		return ratio;
	}
}