I needed to make a few minor changes to make this code work with the new

version of dlib.

tools/mltool/src/regression.cpp

@@ -194,14 +194,15 @@ krr_rbk_test (
          gamma = gamma_range.get_next_value (gamma))
     {
         // LOO cross validation
-        double loo_error;
+        std::vector<double> loo_values;
 
         if (parser.option("verbose")) {
             trainer.set_search_lambdas(logspace(-9, 4, 100));
             trainer.be_verbose();
         }
         trainer.set_kernel (kernel_type (gamma));
-        trainer.train (dense_samples, labels, loo_error);
+        trainer.train (dense_samples, labels, loo_values);
+        const double loo_error = mean_squared_error(loo_values, labels);
         if (loo_error < best_loo) {
             best_loo = loo_error;
             best_gamma = gamma;
@@ -237,9 +238,12 @@ krr_lin_test (
     krr_trainer<kernel_type> trainer;
 
     // LOO cross validation
-    double loo_error;
-    trainer.train(dense_samples, labels, loo_error);
+    std::vector<double> loo_values;
+    trainer.train(dense_samples, labels, loo_values);
+    const double loo_error = mean_squared_error(loo_values, labels);
+    const double rs = r_squared(loo_values, labels);
     std::cout << "mean squared LOO error: " << loo_error << std::endl;
+    std::cout << "R-Squared LOO: " << rs << std::endl;
 }
 
 // ----------------------------------------------------------------------------------------
@@ -343,11 +347,11 @@ svr_test (
              gamma = gamma_range.get_next_value (gamma))
         {
             cout << "test with svr-C: " << svr_c << "   gamma: "<< gamma << flush;
-            double cv_error;
+            matrix<double,1,2> cv;
             trainer.set_kernel (kernel_type (gamma));
-            cv_error = cross_validate_regression_trainer (trainer, 
-                                                          dense_samples, labels, 10);
-            cout << "   10-fold-MSE: "<< cv_error << endl;
+            cv = cross_validate_regression_trainer (trainer, dense_samples, labels, 10);
+            cout << "   10-fold-MSE:       "<< cv(0) << endl;
+            cout << "   10-fold-R-Squared: "<< cv(1) << endl;
         }
     }
 }