Adding folder for testing discrete calculators;

First version of unit tests for MI discrete

java/unittests/infodynamics/measures/discrete/MutualInformationTester.java

@@ -0,0 +1,55 @@
+package infodynamics.measures.discrete;
+
+import junit.framework.TestCase;
+
+public class MutualInformationTester extends TestCase {
+
+	public void testFullyDependent() {
+		MutualInformationCalculator miCalc = new MutualInformationCalculator(2, 0);
+		
+		// X2 is a copy of X1 - MI should be 1 bit
+		miCalc.initialise();
+		miCalc.addObservations(new int[] {0, 0, 1, 1}, new int[] {0, 0, 1, 1});
+		double miCopy = miCalc.computeAverageLocalOfObservations();
+		assertEquals(1.0, miCopy, 0.000001);
+	}
+	
+	public void testIndependent() {
+		MutualInformationCalculator miCalc = new MutualInformationCalculator(2, 0);
+		
+		// X2 is unrelated to X1 - MI should be 0 bits
+		miCalc.initialise();
+		miCalc.addObservations(new int[] {0, 0, 1, 1}, new int[] {0, 1, 0, 1});
+		double miRand = miCalc.computeAverageLocalOfObservations();
+		assertEquals(0.0, miRand, 0.000001);
+	}
+
+	public void testXor() {
+		MutualInformationCalculator miCalc = new MutualInformationCalculator(2, 0);
+		
+		int[] X1 = new int[] {0, 0, 1, 1};
+		int[] X2 = new int[] {0, 1, 0, 1};
+		int[] Y  = new int[] {0, 1, 1, 0};
+		
+		// Y is independent of X1 - MI should be 0 bits
+		miCalc.initialise();
+		miCalc.addObservations(X1, Y);
+		double miX1Y = miCalc.computeAverageLocalOfObservations();
+		assertEquals(0.0, miX1Y, 0.000001);
+
+		// Y is independent of X2 - MI should be 0 bits
+		miCalc.initialise();
+		miCalc.addObservations(X2, Y);
+		double miX2Y = miCalc.computeAverageLocalOfObservations();
+		assertEquals(0.0, miX2Y, 0.000001);
+		
+		// Y is fully determined from X1, X2 - MI should be 0 bits
+		MutualInformationCalculator miCalcBase4 = new MutualInformationCalculator(4, 0);
+		int[] X12 = new int[] {0, 1, 2, 3};
+		miCalcBase4.initialise();
+		miCalcBase4.addObservations(X12, Y);
+		miCalcBase4.setDebug(true);
+		double miX12Y = miCalcBase4.computeAverageLocalOfObservations();
+		assertEquals(1.0, miX12Y, 0.000001);
+	}
+}