/**
 * 
 */
package ie.dcu.eval;

import ie.dcu.matrix.ByteMatrix;

/**
 * An evaluator that computes several standard statistical measure using a
 * confusion matrix.
 * 
 * @author Kevin McGuinness
 */
public class ConfusionMatrixEvaluator extends AbstractEvaluator {
	public static final String ACCURACY  = "Accuracy";
	public static final String PRECISION = "Precision";
	public static final String RECALL    = "Recall";
	public static final String F_MEASURE = "F-Measure";
	public static final String JACCARD   = "Jaccard";

	public ConfusionMatrixEvaluator() {
		name = "Confusion Matrix Evaluator";
		description = "Computes standard measures using a confusion matrix";
		vendor = "Kevin McGuinness";
	
		// Add measures
		addMeasure(ACCURACY);
		addMeasure(PRECISION);
		addMeasure(RECALL);
		addMeasure(F_MEASURE);
		addMeasure(JACCARD);
	}
	
	
	public void run(ByteMatrix a, ByteMatrix b) {

		// Check preconditions
		check(a, b);		
		
		// Confusion matrix (confused? :-P)
		int[][] c = new int[2][2];
	
		// Zero matrix
		for (int i = 0; i < 2; i++) {
			for (int j = 0; j < 2; j++) {
				c[i][j] = 0;
			}
		}
		
		// Compute confusion
		for (int i = 0; i < a.size; i++) {
			
			// Indices into confusion matrix
			int idx1 = a.values[i] == FG ? 0 : 1;
			int idx2 = b.values[i] == FG ? 0 : 1;
			
			// Increment confusion
			c[idx1][idx2]++;
		}
		
		// Compute measures and set results
		BinaryClassifierEvaluation ev = 
			new BinaryClassifierEvaluation(c);
		
		// Set results
		setResult(ACCURACY, ev.getAccuracy());
		setResult(PRECISION, ev.getPrecision());
		setResult(RECALL, ev.getRecall());
		setResult(F_MEASURE, ev.getFMeasure());
		setResult(JACCARD, ev.getJaccardIndex());
	}
}