remove warning on comparision edge case

Author: jreback

pandas/core/dtypes/missing.py

@@ -316,6 +316,10 @@ def array_equivalent(left, right, strict_nan=False):
 
     # NaNs can occur in float and complex arrays.
     if is_float_dtype(left) or is_complex_dtype(left):
+
+        # empty
+        if not (np.prod(left.shape) and np.prod(right.shape)):
+            return True
         return ((left == right) | (isna(left) & isna(right))).all()
 
     # numpy will will not allow this type of datetimelike vs integer comparison

pandas/tests/plotting/test_misc.py

@@ -206,6 +206,7 @@ def test_parallel_coordinates(self):
     def test_parallel_coordinates_with_sorted_labels(self):
         """ For #15908 """
         from pandas.plotting import parallel_coordinates
+
         df = DataFrame({"feat": [i for i in range(30)],
                         "class": [2 for _ in range(10)] +
                         [3 for _ in range(10)] +

pandas/tests/util/test_testing.py

@@ -48,12 +48,18 @@ def test_assert_almost_equal_numbers_with_mixed(self):
         self._assert_not_almost_equal_both(1, [1, ])
         self._assert_not_almost_equal_both(1, object())
 
-    def test_assert_almost_equal_edge_case_ndarrays(self):
-        self._assert_almost_equal_both(np.array([], dtype='M8[ns]'),
-                                       np.array([], dtype='float64'),
-                                       check_dtype=False)
-        self._assert_almost_equal_both(np.array([], dtype=str),
-                                       np.array([], dtype='int64'),
+    @pytest.mark.parametrize(
+        "left_dtype",
+        ['M8[ns]', 'm8[ns]', 'float64', 'int64', 'object'])
+    @pytest.mark.parametrize(
+        "right_dtype",
+        ['M8[ns]', 'm8[ns]', 'float64', 'int64', 'object'])
+    def test_assert_almost_equal_edge_case_ndarrays(
+            self, left_dtype, right_dtype):
+
+        # empty compare
+        self._assert_almost_equal_both(np.array([], dtype=left_dtype),
+                                       np.array([], dtype=right_dtype),
                                        check_dtype=False)
 
     def test_assert_almost_equal_dicts(self):