bounds_transformer could bypass global_bounds due to the test logic within _trim function in domain_reduction.py

bayes_opt/domain_reduction.py

@@ -97,15 +97,23 @@ def _update(self, target_space: TargetSpace) -> None:
         self.r = self.contraction_rate * self.r
 
     def _trim(self, new_bounds: np.array, global_bounds: np.array) -> np.array:
-        for i, variable in enumerate(new_bounds):
-            if variable[0] < global_bounds[i, 0]:
-                variable[0] = global_bounds[i, 0]
-            if variable[1] > global_bounds[i, 1]:
-                variable[1] = global_bounds[i, 1]
+        """ Tests new_bounds to enforce global_bounds and minimum_window."""
+        # sort the order of the bounds for each parameter
+        for i, pbounds in enumerate(new_bounds):
+            if pbounds[0] > pbounds[1]:
+                new_bounds[i, 0] = pbounds[1]
+                new_bounds[i, 1] = pbounds[0]
+
+        # check if the new bounds exceed the global bounds
+        for i, pbounds in enumerate(new_bounds):
+            # check if lower bound exceeds range 
+            if (pbounds[0] < global_bounds[i, 0] or pbounds[0] > global_bounds[i, 1]):
+                pbounds[0] = global_bounds[i, 0]
+            # check if upper bound exceeds range
+            if (pbounds[1] > global_bounds[i, 1] or pbounds[1] < global_bounds[i, 0]):
+                pbounds[1] = global_bounds[i, 1]
+
         for i, entry in enumerate(new_bounds):
-            if entry[0] > entry[1]:
-                new_bounds[i, 0] = entry[1]
-                new_bounds[i, 1] = entry[0]
             window_width = abs(entry[0] - entry[1])
             if window_width < self.minimum_window[i]:
                 dw = (self.minimum_window[i] - window_width) / 2.0

tests/test_seq_domain_red.py

@@ -143,4 +143,36 @@ def test_exceeded_bounds():
                 verbose=0,
                 random_state=1,
                 bounds_transformer=bounds_transformer
-            )
+            )
+
+def test_trim_both_new_bounds_beyond_gloabal_bounds():
+    """Test if the global bounds are respected when both new bounds for a given parameter
+    are beyond the global bounds."""
+
+    # initialize a bounds transformer
+    bounds_transformer = SequentialDomainReductionTransformer(minimum_window=10)
+    pbounds  = {'x': (-10, 10),'y': (-10, 10)}
+    target_sp = TargetSpace(target_func=black_box_function, pbounds=pbounds)
+    bounds_transformer.initialize(target_sp)
+    global_bounds = np.asarray(list(pbounds.values()))
+
+    def verify_bounds_in_range(new_bounds, global_bounds):
+        """Check if the new bounds are within the global bounds."""
+        test = True
+        for i, pbounds in enumerate(new_bounds):
+            if (pbounds[0] < global_bounds[i, 0] or pbounds[0] > global_bounds[i, 1]):
+                test = False
+            if (pbounds[1] > global_bounds[i, 1] or pbounds[1] < global_bounds[i, 0]):
+                test = False
+        return test
+
+    # test if both bounds for one parameter are beyond the global bounds
+    new_bounds = np.array( [[-50, -20], [-10, 10]] )
+    trimmed_bounds = bounds_transformer._trim(new_bounds, global_bounds)
+    assert verify_bounds_in_range(trimmed_bounds, global_bounds)
+
+    # test if both bounds for one parameter are beyond the global bounds 
+    # while they are out of order
+    new_bounds = np.array( [[-20, -50], [-10, 10]] )
+    trimmed_bounds = bounds_transformer._trim(new_bounds, global_bounds)
+    assert verify_bounds_in_range(trimmed_bounds, global_bounds)