warn when registering array

Author: till-m

bayes_opt/target_space.py

@@ -102,6 +102,8 @@ def __init__(
             else:
                 self._constraint_values = np.empty(shape=(0, constraint.lb.size), dtype=float)
 
+        self._sorting_warning_already_shown = False  # TODO: remove in future version
+
     def __contains__(self, x: NDArray[Float]) -> bool:
         """Check if this parameter has already been registered.
 
@@ -330,6 +332,17 @@ def register(
         >>> len(space)
         1
         """
+        # TODO: remove in future version
+        if isinstance(params, np.ndarray) and not self._sorting_warning_already_shown:
+            msg = (
+                "You're attempting to register an np.ndarray. Currently, the optimizer internally sorts"
+                " parameters by key and expects any registered array to respect this order. In future"
+                " versions this behaviour will change and the order as given by the pbounds dictionary"
+                " will be used. If you wish to retain sorted parameters, please manually sort your pbounds"
+                " dictionary before constructing the optimizer."
+            )
+            warn(msg, stacklevel=1)
+            self._sorting_warning_already_shown = True
         x = self._as_array(params)
         if x in self:
             if self._allow_duplicate_points: