LIBLINEAR1.93のcross validationオプションでprecision/recallを出力する

train.patch

--- train.c 2012-10-29 01:46:32.000000000 +0900
+++ train-new.c	2013-02-12 19:53:21.000000000 +0900
@@ -135,10 +135,14 @@
 void do_cross_validation()
 {
 	int i;
-	int total_correct = 0;
 	double total_error = 0;
 	double sumv = 0, sumy = 0, sumvv = 0, sumyy = 0, sumvy = 0;
 	double *target = Malloc(double, prob.l);
+	//** To caluculate precision/recall for each class **/
+	int tp = 0;
+	int fp = 0;
+	int tn = 0;
+	int fn = 0;
 
 	cross_validation(&prob,&param,nr_fold,target);
 	if(param.solver_type == L2R_L2LOSS_SVR ||
@@ -164,10 +168,42 @@
 	}
 	else
 	{
-		for(i=0;i<prob.l;i++)
-			if(target[i] == prob.y[i])
-				++total_correct;
-		printf("Cross Validation Accuracy = %g%%\n",100.0*total_correct/prob.l);
+		for(i=0;i<prob.l; i++) {
+			if(prob.y[i] == 1) { // True label = +1
+				if(target[i] == prob.y[i]) {
+					tp++;
+				} else {
+					fp++;
+				}
+			} else { // True label = -1
+				if (target[i] == prob.y[i]) {
+					tn++;
+				} else {
+					fn++;
+				}
+			}
+		}
+
+		printf("Cross Validation Accuracy = %g%%\n",100.0 * ((double)(tp + tn) / (double)(tp + fp + tn + fn)) );
+ 
+		// Precision and recall
+		double pos_prec	 = ((double)tp/(double)(tp + fp));
+		double pos_rec		= ((double)tp/(double)(tp + fn));
+		double pos_f1		 = (2 * pos_prec * pos_rec) / (pos_prec + pos_rec);
+
+		double neg_prec	 = ((double)tn/(double)(tn + fn));
+		double neg_rec		= ((double)tn/(double)(tn + fp));
+		double neg_f1		 = (2 * neg_prec * neg_rec) / (neg_prec + neg_rec);
+			
+		printf("Positive (+1) class:\n");
+		printf("  precision = %g\n", pos_prec );
+		printf("     recall = %g\n", pos_rec );
+		printf("   F1 value = %g\n\n", pos_f1 );
+
+		printf("Negative (-1) class:\n");
+		printf("  precision = %g\n", neg_prec );
+		printf("     recall = %g\n", neg_rec );
+		printf("   F1 value = %g\n\n", neg_f1 );
 	}
 
 	free(target);
@@ -397,3 +433,4 @@
 
 	fclose(fp);
 }
+