Add edge case to 2d Pareto front algorithm.

optuna · Mar 23, 2021 · 54c51a6 · 54c51a6
1 parent 11b5187
commit 54c51a6
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Showing 2 changed files with 4 additions and 1 deletion.
diff --git a/optuna/_multi_objective.py b/optuna/_multi_objective.py
@@ -34,7 +34,7 @@ def set_mask(width: int, hi: int) -> None:
         if curr_x != x:
             set_mask(width, hi=i)
             width = 0
-        if y > best_y:
+        if y > best_y or (y == best_y and width == 0):
             continue
         if y < best_y:
             width = 0

diff --git a/tests/study_tests/test_study.py b/tests/study_tests/test_study.py
@@ -831,6 +831,9 @@ def _trial_to_values(t: FrozenTrial) -> Tuple[float, ...]:
     study.optimize(lambda t: [3, 1], n_trials=1)
     assert {_trial_to_values(t) for t in study.best_trials} == {(1, 1), (2, 2)}
 
+    study.optimize(lambda t: [3, 2], n_trials=1)
+    assert {_trial_to_values(t) for t in study.best_trials} == {(1, 1), (2, 2)}
+
     study.optimize(lambda t: [1, 3], n_trials=1)
     assert {_trial_to_values(t) for t in study.best_trials} == {(1, 3)}
     assert len(study.best_trials) == 1