ENH: add OO->? loops, use np.compare(a, b, dtype=bool), add comments

2 files changed, 5 insertions, 1 deletions

diff --git a/numpy/lib/arraysetops.py b/numpy/lib/arraysetops.py
index c30ad534b..cf45e181b 100644
--- a/numpy/lib/arraysetops.py
+++ b/numpy/lib/arraysetops.py
@@ -562,10 +562,14 @@ def in1d(ar1, ar2, assume_unique=False, invert=False):
         if invert:
             mask = np.ones(len(ar1), dtype=bool)
             for a in ar2:
+                # convert object arrays to bool
+                # cannot use np.not_equal until 'S' and 'U' have loops
                 mask &= (ar1 != a).astype(bool)
         else:
             mask = np.zeros(len(ar1), dtype=bool)
             for a in ar2:
+                # convert object arrays to bool
+                # cannot use np.equal until 'S' and 'U' have loops
                 mask |= (ar1 == a).astype(bool)
         return mask
 
diff --git a/numpy/lib/nanfunctions.py b/numpy/lib/nanfunctions.py
index 0ae74bbbb..457cca146 100644
--- a/numpy/lib/nanfunctions.py
+++ b/numpy/lib/nanfunctions.py
@@ -99,7 +99,7 @@ def _replace_nan(a, val):
 
     if a.dtype == np.object_:
         # object arrays do not support `isnan` (gh-9009), so make a guess
-        mask = (a != a).astype(bool)
+        mask = np.not_equal(a, a, dtype=bool)
     elif issubclass(a.dtype.type, np.inexact):
         mask = np.isnan(a)
     else: