Improve epsilon calculation in MIPExplainer class

ocean/mip/_explainer.py

@@ -2,6 +2,7 @@
 import warnings
 
 import gurobipy as gp
+import numpy as np
 from sklearn.ensemble import IsolationForest
 
 from ..abc import Mapper
@@ -46,13 +47,23 @@ def __init__(
             max_samples=max_samples,
             name=name,
             env=env,
-            epsilon=epsilon,
+            epsilon=self.__find_best_num_epsilon(epsilon, mapper),
             num_epsilon=num_epsilon,
             model_type=model_type,
             flow_type=flow_type,
         )
         self.build()
 
+    @staticmethod
+    def __find_best_num_epsilon(
+        epsilon: float, mapper: Mapper[Feature]
+    ) -> float:
+        eps = epsilon
+        for f in mapper.values():
+            if f.is_numeric:
+                eps = min(eps, *np.diff(f.levels) / 2.0)
+        return eps
+
     def get_objective_value(self) -> float:
         return self.ObjVal