handling case where no path is reachable

path_planning_evaluate.py

@@ -215,9 +215,9 @@ class Path_Planning_evaluate(evaluate.Metric):
         r_metrics = {}
         r_metrics.update({ 
             'compliance_ratio': metrics['compliance']/(total_reach+total_unreach), 
-            'success_ratio': metrics['correct']/total_reach, 
-            'optimal_ratio': metrics['optimal']/total_reach, 
-            'feasible_ratio': metrics['feasible']/total_reach, 
+            'success_ratio': metrics['correct']/total_reach if total_reach > 0 else -1, 
+            'optimal_ratio': metrics['optimal']/total_reach if total_reach > 0 else -1, 
+            'feasible_ratio': metrics['feasible']/total_reach if total_reach > 0 else -1, 
             'distance': metrics['distance']/diff if diff > 0 else metrics['distance'],
             'unreachable_acc': metrics['n_detect_unreachable']/total_unreach if total_unreach > 0 else -1,
         })