From a502c1b5ff94c4b6b88b8f7150351d06038220c5 Mon Sep 17 00:00:00 2001
From: Patrick Kunzmann <padix.key@gmail.com>
Date: Mon, 5 May 2025 16:37:35 +0200
Subject: [PATCH] Selectors do not raise a warning, if input values are NaN

---
 src/peppr/selector.py   | 10 ++++++++++
 tests/test_selectors.py | 26 ++++++++++++++++++++++++++
 2 files changed, 36 insertions(+)

diff --git a/src/peppr/selector.py b/src/peppr/selector.py
index fcd4728..c9016d0 100644
--- a/src/peppr/selector.py
+++ b/src/peppr/selector.py
@@ -74,6 +74,8 @@ def name(self) -> str:
         return "mean"
 
     def select(self, values: np.ndarray, smaller_is_better: bool) -> float:
+        if np.isnan(values).all():
+            return np.nan
         return np.nanmean(values)
 
 
@@ -87,6 +89,8 @@ def name(self) -> str:
         return "median"
 
     def select(self, values: np.ndarray, smaller_is_better: bool) -> float:
+        if np.isnan(values).all():
+            return np.nan
         return np.nanmedian(values)
 
 
@@ -100,6 +104,8 @@ def name(self) -> str:
         return "Oracle"
 
     def select(self, values: np.ndarray, smaller_is_better: bool) -> float:
+        if np.isnan(values).all():
+            return np.nan
         if smaller_is_better:
             return np.nanmin(values)
         else:
@@ -126,6 +132,8 @@ def name(self) -> str:
 
     def select(self, values: np.ndarray, smaller_is_better: bool) -> float:
         top_values = values[: self._k]
+        if np.isnan(top_values).all():
+            return np.nan
         if smaller_is_better:
             return np.nanmin(top_values)
         else:
@@ -160,6 +168,8 @@ def select(self, values: np.ndarray, smaller_is_better: bool) -> float:
             range(len(values)), size=self._k, replace=False
         )
         top_values = values[random_indices]
+        if np.isnan(top_values).all():
+            return np.nan
         if smaller_is_better:
             return np.nanmin(top_values)
         else:
diff --git a/tests/test_selectors.py b/tests/test_selectors.py
index 6ad7d8b..bfa32c1 100644
--- a/tests/test_selectors.py
+++ b/tests/test_selectors.py
@@ -28,6 +28,32 @@ def test_selectors(selector, expected_value):
     assert selected_value == expected_value
 
 
+@pytest.mark.filterwarnings("error")
+@pytest.mark.parametrize("smaller_is_better", [False, True])
+@pytest.mark.parametrize(
+    "selector",
+    [
+        peppr.MeanSelector(),
+        peppr.OracleSelector(),
+        peppr.TopSelector(5),
+        peppr.TopSelector(1),
+        peppr.RandomSelector(5, seed=0),
+    ],
+    ids=lambda selector: selector.name,
+)
+def test_nan_values(selector, smaller_is_better):
+    """
+    Check that :meth:`Selector.select()` returns NaN if all values are NaN, without
+    raising a warnings.
+    If any value is not NaN, the selector should return an actual value.
+    """
+    values = np.full(10, np.nan)
+    assert np.isnan(selector.select(values, smaller_is_better))
+    # Expect a non-NaN value if the input contains any non-NaN value
+    values = np.concatenate([np.arange(9), [np.nan]])
+    assert not np.isnan(selector.select(values, smaller_is_better))
+
+
 def test_random_selector():
     """
     Test the RandomSelector's statistical behavior.