MAINT: Let _remove_nan_1d attempt to identify nan-containing object arrays

Bas van Beek · howjmay · commit d9b27a05d068 · 2021-09-29T23:44:35.000+08:00
Use the same approach as in numpy#9013
diff --git a/numpy/lib/nanfunctions.py b/numpy/lib/nanfunctions.py
@@ -161,9 +161,11 @@ def _remove_nan_1d(arr1d, overwrite_input=False):
         input
     """
     if arr1d.dtype == object:
-        return arr1d, True
+        # object arrays do not support `isnan` (gh-9009), so make a guess
+        c = np.not_equal(arr1d, arr1d, dtype=bool)
+    else:
+        c = np.isnan(arr1d)
 
-    c = np.isnan(arr1d)
     s = np.nonzero(c)[0]
     if s.size == arr1d.size:
         warnings.warn("All-NaN slice encountered", RuntimeWarning,
