From 36c8b885373e13ef98545bc7a638936ee8c1a297 Mon Sep 17 00:00:00 2001
From: Dave hughes <2043653+dwhu@users.noreply.github.com>
Date: Fri, 3 Jan 2020 09:23:37 -0800
Subject: [PATCH 01/15] ENH: .equals for Extension Arrays

---
 pandas/core/arrays/base.py           | 50 ++++++++++++++++++++++++++++
 pandas/core/arrays/boolean.py        | 14 ++++++++
 pandas/core/arrays/categorical.py    | 13 ++++++++
 pandas/core/arrays/integer.py        | 13 ++++++++
 pandas/core/arrays/interval.py       | 15 +++++++++
 pandas/tests/extension/json/array.py | 10 ++++++
 6 files changed, 115 insertions(+)

diff --git a/pandas/core/arrays/base.py b/pandas/core/arrays/base.py
index 96a4eb1b3bf32..edbf1e62f89fc 100644
--- a/pandas/core/arrays/base.py
+++ b/pandas/core/arrays/base.py
@@ -78,6 +78,7 @@ class ExtensionArray:
     dropna
     factorize
     fillna
+    equals
     isna
     ravel
     repeat
@@ -350,6 +351,38 @@ def __iter__(self):
         for i in range(len(self)):
             yield self[i]
 
+    def __eq__(self, other: ABCExtensionArray) -> bool:
+        """
+        Whether the two arrays are equivalent.
+
+        Parameters
+        ----------
+        other: ExtensionArray
+            The array to compare to this array.
+
+        Returns
+        -------
+        bool
+        """
+
+        raise AbstractMethodError(self)
+
+    def __ne__(self, other: ABCExtensionArray) -> bool:
+        """
+        Whether the two arrays are not equivalent.
+
+        Parameters
+        ----------
+        other: ExtensionArray
+            The array to compare to this array.
+
+        Returns
+        -------
+        bool
+        """
+
+        raise AbstractMethodError(self)
+
     # ------------------------------------------------------------------------
     # Required attributes
     # ------------------------------------------------------------------------
@@ -657,6 +690,23 @@ def searchsorted(self, value, side="left", sorter=None):
         arr = self.astype(object)
         return arr.searchsorted(value, side=side, sorter=sorter)
 
+    def equals(self, other: ABCExtensionArray) -> bool:
+        """
+        Return if another array is equivalent to this array.
+
+        Parameters
+        ----------
+        other: ExtensionArray
+            Array to compare to this Array.
+
+        Returns
+        -------
+        boolean
+            Whether the arrays are equivalent.
+
+        """
+        return ((self == other) | (self.isna() == other.isna())).all()
+
     def _values_for_factorize(self) -> Tuple[np.ndarray, Any]:
         """
         Return an array and missing value suitable for factorization.
diff --git a/pandas/core/arrays/boolean.py b/pandas/core/arrays/boolean.py
index 102150b1cbce1..762bedbd67a43 100644
--- a/pandas/core/arrays/boolean.py
+++ b/pandas/core/arrays/boolean.py
@@ -327,6 +327,20 @@ def __getitem__(self, item):
 
         return type(self)(self._data[item], self._mask[item])
 
+    def __eq__(self, other):
+        if not isinstance(other, BooleanArray):
+            return NotImplemented
+        return (
+            hasattr(other, "_data")
+            and self._data == other._data
+            and hasattr(other, "_mask")
+            and self._mask == other._mask
+            and hasattr(other, "_dtype") & self._dtype == other._dtype
+        )
+
+    def __ne__(self, other):
+        return not self.__eq__(other)
+
     def _coerce_to_ndarray(self, dtype=None, na_value: "Scalar" = libmissing.NA):
         """
         Coerce to an ndarray of object dtype or bool dtype (if force_bool=True).
diff --git a/pandas/core/arrays/categorical.py b/pandas/core/arrays/categorical.py
index f4e75364ae932..6b8260076f70a 100644
--- a/pandas/core/arrays/categorical.py
+++ b/pandas/core/arrays/categorical.py
@@ -2071,6 +2071,19 @@ def __setitem__(self, key, value):
         lindexer = self._maybe_coerce_indexer(lindexer)
         self._codes[key] = lindexer
 
+    def __eq__(self, other):
+        if not isinstance(other, Categorical):
+            return NotImplemented
+        return (
+            hasattr(other, "_codes")
+            and self._codes == other._codes
+            and hasattr(other, "_dtype")
+            and self._dtype == other._dtype
+        )
+
+    def __ne__(self, other):
+        return not self.__eq__(other)
+
     def _reverse_indexer(self) -> Dict[Hashable, np.ndarray]:
         """
         Compute the inverse of a categorical, returning
diff --git a/pandas/core/arrays/integer.py b/pandas/core/arrays/integer.py
index 0922f4ac6f71d..e0306a4c4eec9 100644
--- a/pandas/core/arrays/integer.py
+++ b/pandas/core/arrays/integer.py
@@ -376,6 +376,19 @@ def __getitem__(self, item):
 
         return type(self)(self._data[item], self._mask[item])
 
+    def __eq__(self, other):
+        if not isinstance(other, IntegerArray):
+            return NotImplemented
+        return (
+            hasattr(other, "_data")
+            and self._data == other._data
+            and hasattr(other, "_mask")
+            and self._mask == other._mask
+        )
+
+    def __ne__(self, other):
+        return not self.__eq__(other)
+
     def _coerce_to_ndarray(self, dtype=None, na_value=lib._no_default):
         """
         coerce to an ndarary of object dtype
diff --git a/pandas/core/arrays/interval.py b/pandas/core/arrays/interval.py
index cea059fb22be1..e839ba7e23e77 100644
--- a/pandas/core/arrays/interval.py
+++ b/pandas/core/arrays/interval.py
@@ -547,6 +547,21 @@ def __setitem__(self, key, value):
         right.values[key] = value_right
         self._right = right
 
+    def __eq__(self, other):
+        if not isinstance(other, IntervalArray):
+            return NotImplementedError
+        return (
+            hasattr(other, "_left")
+            and self._left == other._left
+            and hasattr(other, "_right")
+            and self._right == other._right
+            and hasattr(other, "_closed")
+            and self._closed == other._closed
+        )
+
+    def __ne__(self, other):
+        return not self.__eq__(other)
+
     def fillna(self, value=None, method=None, limit=None):
         """
         Fill NA/NaN values using the specified method.
diff --git a/pandas/tests/extension/json/array.py b/pandas/tests/extension/json/array.py
index 17bc2773aad19..89e55e1b0e7cd 100644
--- a/pandas/tests/extension/json/array.py
+++ b/pandas/tests/extension/json/array.py
@@ -110,6 +110,16 @@ def __setitem__(self, key, value):
                     assert isinstance(v, self.dtype.type)
                     self.data[k] = v
 
+    def __eq__(self, other):
+        return (
+            isinstance(other, JSONArray)
+            and hasattr(other, "data")
+            and self.data == other.data
+        )
+
+    def __ne__(self, other):
+        return not self.__eq__(other)
+
     def __len__(self) -> int:
         return len(self.data)
 

From 786963c756780285268f94e66b761a3c3f0e3f78 Mon Sep 17 00:00:00 2001
From: Dave hughes <2043653+dwhu@users.noreply.github.com>
Date: Fri, 3 Jan 2020 11:18:01 -0800
Subject: [PATCH 02/15] ENH: Updating eq and ne methods for extension arrays.

Adding __eq__ to ExtensionArray Abstract method doc string.

Adding ne implementation to EA base class.

Also removing other implementations.

Updating EA equals method and adding tests.

GH-27081
---
 pandas/core/arrays/base.py             |  7 +++++--
 pandas/core/arrays/boolean.py          | 14 --------------
 pandas/core/arrays/categorical.py      | 13 -------------
 pandas/core/arrays/integer.py          |  8 ++------
 pandas/core/arrays/interval.py         | 12 ++++--------
 pandas/tests/extension/base/methods.py | 15 +++++++++++++++
 pandas/tests/extension/base/ops.py     | 12 ------------
 pandas/tests/extension/json/array.py   |  3 ---
 pandas/tests/extension/test_sparse.py  |  4 ++++
 9 files changed, 30 insertions(+), 58 deletions(-)

diff --git a/pandas/core/arrays/base.py b/pandas/core/arrays/base.py
index edbf1e62f89fc..6aabd6df24e32 100644
--- a/pandas/core/arrays/base.py
+++ b/pandas/core/arrays/base.py
@@ -105,6 +105,7 @@ class ExtensionArray:
     * _from_sequence
     * _from_factorized
     * __getitem__
+    * __eq__
     * __len__
     * dtype
     * nbytes
@@ -381,7 +382,7 @@ def __ne__(self, other: ABCExtensionArray) -> bool:
         bool
         """
 
-        raise AbstractMethodError(self)
+        return ~(self == other)
 
     # ------------------------------------------------------------------------
     # Required attributes
@@ -705,7 +706,9 @@ def equals(self, other: ABCExtensionArray) -> bool:
             Whether the arrays are equivalent.
 
         """
-        return ((self == other) | (self.isna() == other.isna())).all()
+        return isinstance(other, self.__class__) and (
+            ((self == other) | (self.isna() == other.isna())).all()
+        )
 
     def _values_for_factorize(self) -> Tuple[np.ndarray, Any]:
         """
diff --git a/pandas/core/arrays/boolean.py b/pandas/core/arrays/boolean.py
index 762bedbd67a43..102150b1cbce1 100644
--- a/pandas/core/arrays/boolean.py
+++ b/pandas/core/arrays/boolean.py
@@ -327,20 +327,6 @@ def __getitem__(self, item):
 
         return type(self)(self._data[item], self._mask[item])
 
-    def __eq__(self, other):
-        if not isinstance(other, BooleanArray):
-            return NotImplemented
-        return (
-            hasattr(other, "_data")
-            and self._data == other._data
-            and hasattr(other, "_mask")
-            and self._mask == other._mask
-            and hasattr(other, "_dtype") & self._dtype == other._dtype
-        )
-
-    def __ne__(self, other):
-        return not self.__eq__(other)
-
     def _coerce_to_ndarray(self, dtype=None, na_value: "Scalar" = libmissing.NA):
         """
         Coerce to an ndarray of object dtype or bool dtype (if force_bool=True).
diff --git a/pandas/core/arrays/categorical.py b/pandas/core/arrays/categorical.py
index 6b8260076f70a..f4e75364ae932 100644
--- a/pandas/core/arrays/categorical.py
+++ b/pandas/core/arrays/categorical.py
@@ -2071,19 +2071,6 @@ def __setitem__(self, key, value):
         lindexer = self._maybe_coerce_indexer(lindexer)
         self._codes[key] = lindexer
 
-    def __eq__(self, other):
-        if not isinstance(other, Categorical):
-            return NotImplemented
-        return (
-            hasattr(other, "_codes")
-            and self._codes == other._codes
-            and hasattr(other, "_dtype")
-            and self._dtype == other._dtype
-        )
-
-    def __ne__(self, other):
-        return not self.__eq__(other)
-
     def _reverse_indexer(self) -> Dict[Hashable, np.ndarray]:
         """
         Compute the inverse of a categorical, returning
diff --git a/pandas/core/arrays/integer.py b/pandas/core/arrays/integer.py
index e0306a4c4eec9..4b0d4d65924cd 100644
--- a/pandas/core/arrays/integer.py
+++ b/pandas/core/arrays/integer.py
@@ -377,18 +377,14 @@ def __getitem__(self, item):
         return type(self)(self._data[item], self._mask[item])
 
     def __eq__(self, other):
-        if not isinstance(other, IntegerArray):
-            return NotImplemented
         return (
-            hasattr(other, "_data")
+            isinstance(other, IntegerArray)
+            and hasattr(other, "_data")
             and self._data == other._data
             and hasattr(other, "_mask")
             and self._mask == other._mask
         )
 
-    def __ne__(self, other):
-        return not self.__eq__(other)
-
     def _coerce_to_ndarray(self, dtype=None, na_value=lib._no_default):
         """
         coerce to an ndarary of object dtype
diff --git a/pandas/core/arrays/interval.py b/pandas/core/arrays/interval.py
index e839ba7e23e77..430c04e00fac8 100644
--- a/pandas/core/arrays/interval.py
+++ b/pandas/core/arrays/interval.py
@@ -548,20 +548,16 @@ def __setitem__(self, key, value):
         self._right = right
 
     def __eq__(self, other):
-        if not isinstance(other, IntervalArray):
-            return NotImplementedError
         return (
-            hasattr(other, "_left")
-            and self._left == other._left
+            isinstance(other, IntervalArray)
+            and hasattr(other, "_left")
+            and np.array_equal(self._left, other._left)
             and hasattr(other, "_right")
-            and self._right == other._right
+            and np.array_equal(self._right, other._right)
             and hasattr(other, "_closed")
             and self._closed == other._closed
         )
 
-    def __ne__(self, other):
-        return not self.__eq__(other)
-
     def fillna(self, value=None, method=None, limit=None):
         """
         Fill NA/NaN values using the specified method.
diff --git a/pandas/tests/extension/base/methods.py b/pandas/tests/extension/base/methods.py
index 973088cb72e7a..6b2144563a74e 100644
--- a/pandas/tests/extension/base/methods.py
+++ b/pandas/tests/extension/base/methods.py
@@ -358,3 +358,18 @@ def test_repeat_raises(self, data, repeats, kwargs, error, msg, use_numpy):
                 np.repeat(data, repeats, **kwargs)
             else:
                 data.repeat(repeats, **kwargs)
+
+    def test_equals(self, data, na_value):
+        cls = type(data)
+        ser = pd.Series(cls._from_sequence(data, dtype=data.dtype))
+        na_ser = pd.Series(cls._from_sequence([na_value], dtype=data.dtype))
+
+        assert data.equals(data)
+        assert ser.equals(ser)
+        assert na_ser.equals(na_ser)
+
+        assert not data.equals(na_value)
+        assert not na_ser.equals(ser)
+        assert not ser.equals(na_ser)
+        assert not ser.equals(0)
+        assert not na_ser.equals(0)
diff --git a/pandas/tests/extension/base/ops.py b/pandas/tests/extension/base/ops.py
index 20d06ef2e5647..0ba5795ea891d 100644
--- a/pandas/tests/extension/base/ops.py
+++ b/pandas/tests/extension/base/ops.py
@@ -132,10 +132,8 @@ class BaseComparisonOpsTests(BaseOpsUtil):
     def _compare_other(self, s, data, op_name, other):
         op = self.get_op_from_name(op_name)
         if op_name == "__eq__":
-            assert getattr(data, op_name)(other) is NotImplemented
             assert not op(s, other).all()
         elif op_name == "__ne__":
-            assert getattr(data, op_name)(other) is NotImplemented
             assert op(s, other).all()
 
         else:
@@ -158,13 +156,3 @@ def test_compare_array(self, data, all_compare_operators):
         s = pd.Series(data)
         other = pd.Series([data[0]] * len(data))
         self._compare_other(s, data, op_name, other)
-
-    def test_direct_arith_with_series_returns_not_implemented(self, data):
-        # EAs should return NotImplemented for ops with Series.
-        # Pandas takes care of unboxing the series and calling the EA's op.
-        other = pd.Series(data)
-        if hasattr(data, "__eq__"):
-            result = data.__eq__(other)
-            assert result is NotImplemented
-        else:
-            raise pytest.skip(f"{type(data).__name__} does not implement __eq__")
diff --git a/pandas/tests/extension/json/array.py b/pandas/tests/extension/json/array.py
index 89e55e1b0e7cd..7c22667e449ff 100644
--- a/pandas/tests/extension/json/array.py
+++ b/pandas/tests/extension/json/array.py
@@ -117,9 +117,6 @@ def __eq__(self, other):
             and self.data == other.data
         )
 
-    def __ne__(self, other):
-        return not self.__eq__(other)
-
     def __len__(self) -> int:
         return len(self.data)
 
diff --git a/pandas/tests/extension/test_sparse.py b/pandas/tests/extension/test_sparse.py
index 6ebe71e173ec2..3fe6335ec63f6 100644
--- a/pandas/tests/extension/test_sparse.py
+++ b/pandas/tests/extension/test_sparse.py
@@ -302,6 +302,10 @@ def test_searchsorted(self, data_for_sorting, as_series):
         with tm.assert_produces_warning(PerformanceWarning):
             super().test_searchsorted(data_for_sorting, as_series)
 
+    def test_equals(self, data, na_value):
+        self._check_unsupported(data)
+        super().test_equals(data, na_value)
+
 
 class TestCasting(BaseSparseTests, base.BaseCastingTests):
     pass

From 6800315753deb7166d68faf511520c61650b9822 Mon Sep 17 00:00:00 2001
From: Dave hughes <2043653+dwhu@users.noreply.github.com>
Date: Fri, 3 Jan 2020 13:50:46 -0800
Subject: [PATCH 03/15] Removing interval.py's __eq__ implementation due to
 conflict with @jschendel change.

---
 pandas/core/arrays/interval.py | 11 -----------
 1 file changed, 11 deletions(-)

diff --git a/pandas/core/arrays/interval.py b/pandas/core/arrays/interval.py
index 430c04e00fac8..cea059fb22be1 100644
--- a/pandas/core/arrays/interval.py
+++ b/pandas/core/arrays/interval.py
@@ -547,17 +547,6 @@ def __setitem__(self, key, value):
         right.values[key] = value_right
         self._right = right
 
-    def __eq__(self, other):
-        return (
-            isinstance(other, IntervalArray)
-            and hasattr(other, "_left")
-            and np.array_equal(self._left, other._left)
-            and hasattr(other, "_right")
-            and np.array_equal(self._right, other._right)
-            and hasattr(other, "_closed")
-            and self._closed == other._closed
-        )
-
     def fillna(self, value=None, method=None, limit=None):
         """
         Fill NA/NaN values using the specified method.

From a3e7b7fd6aa4ea32021fed9d2e3bc308d2b997f1 Mon Sep 17 00:00:00 2001
From: Dave hughes <2043653+dwhu@users.noreply.github.com>
Date: Fri, 3 Jan 2020 14:26:59 -0800
Subject: [PATCH 04/15] ENH: Making EA eq and ne typed as Any.

GH-27081
---
 pandas/core/arrays/base.py | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/pandas/core/arrays/base.py b/pandas/core/arrays/base.py
index 6aabd6df24e32..bb6d0ddb70789 100644
--- a/pandas/core/arrays/base.py
+++ b/pandas/core/arrays/base.py
@@ -352,7 +352,7 @@ def __iter__(self):
         for i in range(len(self)):
             yield self[i]
 
-    def __eq__(self, other: ABCExtensionArray) -> bool:
+    def __eq__(self, other: Any) -> bool:
         """
         Whether the two arrays are equivalent.
 
@@ -368,7 +368,7 @@ def __eq__(self, other: ABCExtensionArray) -> bool:
 
         raise AbstractMethodError(self)
 
-    def __ne__(self, other: ABCExtensionArray) -> bool:
+    def __ne__(self, other: Any) -> bool:
         """
         Whether the two arrays are not equivalent.
 

From 860013f100de5da09de7d0897b0307b02abac0fb Mon Sep 17 00:00:00 2001
From: Dave hughes <2043653+dwhu@users.noreply.github.com>
Date: Fri, 3 Jan 2020 15:31:04 -0800
Subject: [PATCH 05/15] ENH: Adding default implementation to ExtensionArray
 equals() and tests.

GH-27081
---
 pandas/core/arrays/base.py             | 21 +++++++++++++--------
 pandas/core/arrays/integer.py          |  9 ---------
 pandas/tests/extension/base/methods.py |  3 +++
 pandas/tests/extension/json/array.py   |  7 -------
 4 files changed, 16 insertions(+), 24 deletions(-)

diff --git a/pandas/core/arrays/base.py b/pandas/core/arrays/base.py
index bb6d0ddb70789..4c7d20386cb19 100644
--- a/pandas/core/arrays/base.py
+++ b/pandas/core/arrays/base.py
@@ -105,7 +105,6 @@ class ExtensionArray:
     * _from_sequence
     * _from_factorized
     * __getitem__
-    * __eq__
     * __len__
     * dtype
     * nbytes
@@ -358,15 +357,19 @@ def __eq__(self, other: Any) -> bool:
 
         Parameters
         ----------
-        other: ExtensionArray
-            The array to compare to this array.
+        other: Any
+            The object to compare to this array.
 
         Returns
         -------
         bool
         """
 
-        raise AbstractMethodError(self)
+        return (
+            type(self) == type(other)
+            and (self.isna() == other.isna()).all()
+            and np.all(np.array(self) == np.array(other))
+        )
 
     def __ne__(self, other: Any) -> bool:
         """
@@ -374,8 +377,8 @@ def __ne__(self, other: Any) -> bool:
 
         Parameters
         ----------
-        other: ExtensionArray
-            The array to compare to this array.
+        other: Any
+            The object to compare to this array.
 
         Returns
         -------
@@ -706,8 +709,10 @@ def equals(self, other: ABCExtensionArray) -> bool:
             Whether the arrays are equivalent.
 
         """
-        return isinstance(other, self.__class__) and (
-            ((self == other) | (self.isna() == other.isna())).all()
+        return (
+            type(self) == type(other)
+            and (((self == other) | (self.isna() == other.isna())).all())
+            and len(self) == len(other)
         )
 
     def _values_for_factorize(self) -> Tuple[np.ndarray, Any]:
diff --git a/pandas/core/arrays/integer.py b/pandas/core/arrays/integer.py
index 4b0d4d65924cd..0922f4ac6f71d 100644
--- a/pandas/core/arrays/integer.py
+++ b/pandas/core/arrays/integer.py
@@ -376,15 +376,6 @@ def __getitem__(self, item):
 
         return type(self)(self._data[item], self._mask[item])
 
-    def __eq__(self, other):
-        return (
-            isinstance(other, IntegerArray)
-            and hasattr(other, "_data")
-            and self._data == other._data
-            and hasattr(other, "_mask")
-            and self._mask == other._mask
-        )
-
     def _coerce_to_ndarray(self, dtype=None, na_value=lib._no_default):
         """
         coerce to an ndarary of object dtype
diff --git a/pandas/tests/extension/base/methods.py b/pandas/tests/extension/base/methods.py
index 6b2144563a74e..7657b2f787cf8 100644
--- a/pandas/tests/extension/base/methods.py
+++ b/pandas/tests/extension/base/methods.py
@@ -362,6 +362,7 @@ def test_repeat_raises(self, data, repeats, kwargs, error, msg, use_numpy):
     def test_equals(self, data, na_value):
         cls = type(data)
         ser = pd.Series(cls._from_sequence(data, dtype=data.dtype))
+        smaller_ser = pd.Series(cls._from_sequence(data[:5], dtype=data.dtype))
         na_ser = pd.Series(cls._from_sequence([na_value], dtype=data.dtype))
 
         assert data.equals(data)
@@ -371,5 +372,7 @@ def test_equals(self, data, na_value):
         assert not data.equals(na_value)
         assert not na_ser.equals(ser)
         assert not ser.equals(na_ser)
+        assert not ser.equals(smaller_ser)
+        assert not ser.equals(np.asarray(data))
         assert not ser.equals(0)
         assert not na_ser.equals(0)
diff --git a/pandas/tests/extension/json/array.py b/pandas/tests/extension/json/array.py
index 7c22667e449ff..17bc2773aad19 100644
--- a/pandas/tests/extension/json/array.py
+++ b/pandas/tests/extension/json/array.py
@@ -110,13 +110,6 @@ def __setitem__(self, key, value):
                     assert isinstance(v, self.dtype.type)
                     self.data[k] = v
 
-    def __eq__(self, other):
-        return (
-            isinstance(other, JSONArray)
-            and hasattr(other, "data")
-            and self.data == other.data
-        )
-
     def __len__(self) -> int:
         return len(self.data)
 

From c5027dd0c75bf0d1b364a129440c02bddbc84ffa Mon Sep 17 00:00:00 2001
From: Joris Van den Bossche <jorisvandenbossche@gmail.com>
Date: Fri, 1 May 2020 17:39:25 +0200
Subject: [PATCH 06/15] correct __eq/ne__ to be element-wise

---
 pandas/core/arrays/base.py | 37 +++++++------------------------------
 1 file changed, 7 insertions(+), 30 deletions(-)

diff --git a/pandas/core/arrays/base.py b/pandas/core/arrays/base.py
index f403bb751d7d9..fe6b49f7202b3 100644
--- a/pandas/core/arrays/base.py
+++ b/pandas/core/arrays/base.py
@@ -85,6 +85,7 @@ class ExtensionArray:
     * _from_factorized
     * __getitem__
     * __len__
+    * __eq__
     * dtype
     * nbytes
     * isna
@@ -334,40 +335,16 @@ def __iter__(self):
         for i in range(len(self)):
             yield self[i]
 
-    def __eq__(self, other: Any) -> bool:
+    def __eq__(self, other: Any) -> Union[np.ndarray, "ExtensionArray"]:
         """
-        Whether the two arrays are equivalent.
-
-        Parameters
-        ----------
-        other: Any
-            The object to compare to this array.
-
-        Returns
-        -------
-        bool
+        Return for `self == other` (element-wise equality).
         """
+        raise AbstractMethodError(self)
 
-        return (
-            type(self) == type(other)
-            and (self.isna() == other.isna()).all()
-            and np.all(np.array(self) == np.array(other))
-        )
-
-    def __ne__(self, other: Any) -> bool:
+    def __ne__(self, other: Any) -> Union[np.ndarray, "ExtensionArray"]:
         """
-        Whether the two arrays are not equivalent.
-
-        Parameters
-        ----------
-        other: Any
-            The object to compare to this array.
-
-        Returns
-        -------
-        bool
+        Return for `self != other` (element-wise in-equality).
         """
-
         return ~(self == other)
 
     def to_numpy(
@@ -719,7 +696,7 @@ def searchsorted(self, value, side="left", sorter=None):
         arr = self.astype(object)
         return arr.searchsorted(value, side=side, sorter=sorter)
 
-    def equals(self, other: ABCExtensionArray) -> bool:
+    def equals(self, other: "ExtensionArray") -> bool:
         """
         Return if another array is equivalent to this array.
 

From 375664c0907ae698cda9ef22689bee401bd7f1fb Mon Sep 17 00:00:00 2001
From: Joris Van den Bossche <jorisvandenbossche@gmail.com>
Date: Fri, 1 May 2020 18:08:43 +0200
Subject: [PATCH 07/15] fix equals implementation (& instead of ==)

---
 pandas/core/arrays/base.py               | 22 ++++++----
 pandas/tests/extension/base/methods.py   | 51 ++++++++++++++++--------
 pandas/tests/extension/json/test_json.py |  4 ++
 pandas/tests/extension/test_numpy.py     |  5 +++
 4 files changed, 58 insertions(+), 24 deletions(-)

diff --git a/pandas/core/arrays/base.py b/pandas/core/arrays/base.py
index fe6b49f7202b3..6620357402434 100644
--- a/pandas/core/arrays/base.py
+++ b/pandas/core/arrays/base.py
@@ -711,11 +711,17 @@ def equals(self, other: "ExtensionArray") -> bool:
             Whether the arrays are equivalent.
 
         """
-        return (
-            type(self) == type(other)
-            and (((self == other) | (self.isna() == other.isna())).all())
-            and len(self) == len(other)
-        )
+        if not type(self) == type(other):
+            return False
+        elif not len(self) == len(other):
+            return False
+        else:
+            equal_values = self == other
+            if isinstance(equal_values, ExtensionArray):
+                # boolean array with NA -> fill with False
+                equal_values = equal_values.fillna(False)
+            equal_na = self.isna() & other.isna()
+            return (equal_values | equal_na).all().item()
 
     def _values_for_factorize(self) -> Tuple[np.ndarray, Any]:
         """
@@ -1164,7 +1170,7 @@ class ExtensionScalarOpsMixin(ExtensionOpsMixin):
     """
 
     @classmethod
-    def _create_method(cls, op, coerce_to_dtype=True):
+    def _create_method(cls, op, coerce_to_dtype=True, result_dtype=None):
         """
         A class method that returns a method that will correspond to an
         operator for an ExtensionArray subclass, by dispatching to the
@@ -1232,7 +1238,7 @@ def _maybe_convert(arr):
                         # exception raised in _from_sequence; ensure we have ndarray
                         res = np.asarray(arr)
                 else:
-                    res = np.asarray(arr)
+                    res = np.asarray(arr, dtype=result_dtype)
                 return res
 
             if op.__name__ in {"divmod", "rdivmod"}:
@@ -1250,4 +1256,4 @@ def _create_arithmetic_method(cls, op):
 
     @classmethod
     def _create_comparison_method(cls, op):
-        return cls._create_method(op, coerce_to_dtype=False)
+        return cls._create_method(op, coerce_to_dtype=False, result_dtype=bool)
diff --git a/pandas/tests/extension/base/methods.py b/pandas/tests/extension/base/methods.py
index e19dd9db2c7d5..04290319bc592 100644
--- a/pandas/tests/extension/base/methods.py
+++ b/pandas/tests/extension/base/methods.py
@@ -423,19 +423,38 @@ def test_repeat_raises(self, data, repeats, kwargs, error, msg, use_numpy):
                 data.repeat(repeats, **kwargs)
 
     def test_equals(self, data, na_value):
-        cls = type(data)
-        ser = pd.Series(cls._from_sequence(data, dtype=data.dtype))
-        smaller_ser = pd.Series(cls._from_sequence(data[:5], dtype=data.dtype))
-        na_ser = pd.Series(cls._from_sequence([na_value], dtype=data.dtype))
-
-        assert data.equals(data)
-        assert ser.equals(ser)
-        assert na_ser.equals(na_ser)
-
-        assert not data.equals(na_value)
-        assert not na_ser.equals(ser)
-        assert not ser.equals(na_ser)
-        assert not ser.equals(smaller_ser)
-        assert not ser.equals(np.asarray(data))
-        assert not ser.equals(0)
-        assert not na_ser.equals(0)
+        data2 = type(data)._from_sequence([data[0]] * len(data), dtype=data.dtype)
+        data_na = type(data)._from_sequence([na_value] * len(data), dtype=data.dtype)
+
+        assert data.equals(data) is True
+        assert data.equals(data.copy()) is True
+
+        # other data
+        assert data.equals(data2) is False
+        assert data.equals(data_na) is False
+
+        # different length
+        assert data[:2].equals(data[:3]) is False
+
+        # emtpy are equal
+        assert data[:0].equals(data[:0]) is True
+
+        # other types
+        assert data.equals(None) is False
+        assert data[[0]].equals(data[0]) is False
+
+        # TODO test series
+        # ser = pd.Series(data)
+        # smaller_ser = pd.Series(data[:5])
+        # na_ser = pd.Series(type(data)._from_sequence([na_value], dtype=data.dtype))
+
+        # assert ser.equals(ser)
+        # assert na_ser.equals(na_ser)
+
+        # assert not data.equals(na_value)
+        # assert not na_ser.equals(ser)
+        # assert not ser.equals(na_ser)
+        # assert not ser.equals(smaller_ser)
+        # assert not ser.equals(np.asarray(data))
+        # assert not ser.equals(0)
+        # assert not na_ser.equals(0)
diff --git a/pandas/tests/extension/json/test_json.py b/pandas/tests/extension/json/test_json.py
index 745488770e09c..b2b202039b8de 100644
--- a/pandas/tests/extension/json/test_json.py
+++ b/pandas/tests/extension/json/test_json.py
@@ -247,6 +247,10 @@ def test_where_series(self, data, na_value):
     def test_searchsorted(self, data_for_sorting):
         super().test_searchsorted(data_for_sorting)
 
+    @pytest.mark.skip(reason="Can't compare dicts.")
+    def test_equals(self, data, na_value):
+        pass
+
 
 class TestCasting(BaseJSON, base.BaseCastingTests):
     @pytest.mark.skip(reason="failing on np.array(self, dtype=str)")
diff --git a/pandas/tests/extension/test_numpy.py b/pandas/tests/extension/test_numpy.py
index 1c887cc4371b6..aa2f9ea3257f4 100644
--- a/pandas/tests/extension/test_numpy.py
+++ b/pandas/tests/extension/test_numpy.py
@@ -261,6 +261,11 @@ def test_repeat(self, data, repeats, as_series, use_numpy):
     def test_diff(self, data, periods):
         return super().test_diff(data, periods)
 
+    @skip_nested
+    def test_equals(self, data, na_value):
+        # Fails creating with _from_sequence
+        super().test_equals(data, na_value)
+
 
 @skip_nested
 class TestArithmetics(BaseNumPyTests, base.BaseArithmeticOpsTests):

From b6ad2fbc9d96586fe440e6b23effb6154378b1a1 Mon Sep 17 00:00:00 2001
From: Joris Van den Bossche <jorisvandenbossche@gmail.com>
Date: Fri, 1 May 2020 20:32:54 +0200
Subject: [PATCH 08/15] base tests

---
 pandas/tests/extension/base/ops.py   | 10 ++++++++++
 pandas/tests/extension/json/array.py |  6 ++++++
 2 files changed, 16 insertions(+)

diff --git a/pandas/tests/extension/base/ops.py b/pandas/tests/extension/base/ops.py
index f9ab9cb9c28b5..e446ff8178226 100644
--- a/pandas/tests/extension/base/ops.py
+++ b/pandas/tests/extension/base/ops.py
@@ -164,6 +164,16 @@ def test_compare_array(self, data, all_compare_operators):
         other = pd.Series([data[0]] * len(data))
         self._compare_other(s, data, op_name, other)
 
+    def test_direct_arith_with_series_returns_not_implemented(self, data):
+        # EAs should return NotImplemented for ops with Series.
+        # Pandas takes care of unboxing the series and calling the EA's op.
+        other = pd.Series(data)
+        if hasattr(data, "__eq__"):
+            result = data.__eq__(other)
+            assert result is NotImplemented
+        else:
+            raise pytest.skip(f"{type(data).__name__} does not implement __eq__")
+
 
 class BaseUnaryOpsTests(BaseOpsUtil):
     def test_invert(self, data):
diff --git a/pandas/tests/extension/json/array.py b/pandas/tests/extension/json/array.py
index 1f026e405dc17..94f971938b690 100644
--- a/pandas/tests/extension/json/array.py
+++ b/pandas/tests/extension/json/array.py
@@ -105,6 +105,12 @@ def __setitem__(self, key, value):
     def __len__(self) -> int:
         return len(self.data)
 
+    def __eq__(self, other):
+        return NotImplemented
+
+    def __ne__(self, other):
+        return NotImplemented
+
     def __array__(self, dtype=None):
         if dtype is None:
             dtype = object

From 365362ab116a6890bf871ed7115e52c0c63094e0 Mon Sep 17 00:00:00 2001
From: Joris Van den Bossche <jorisvandenbossche@gmail.com>
Date: Fri, 1 May 2020 20:58:24 +0200
Subject: [PATCH 09/15] ensure to dispatch Series.equals to EA.equals

---
 pandas/core/internals/blocks.py          |  5 +++++
 pandas/tests/extension/base/methods.py   | 25 +++++++-----------------
 pandas/tests/extension/json/test_json.py |  2 +-
 pandas/tests/extension/test_numpy.py     |  4 ++--
 pandas/tests/extension/test_sparse.py    |  4 ++--
 5 files changed, 17 insertions(+), 23 deletions(-)

diff --git a/pandas/core/internals/blocks.py b/pandas/core/internals/blocks.py
index afca4ca86bd3f..306d2f5832754 100644
--- a/pandas/core/internals/blocks.py
+++ b/pandas/core/internals/blocks.py
@@ -1861,6 +1861,11 @@ def where(
 
         return [self.make_block_same_class(result, placement=self.mgr_locs)]
 
+    def equals(self, other) -> bool:
+        if self.dtype != other.dtype or self.shape != other.shape:
+            return False
+        return self.values.equals(other.values)
+
     def _unstack(self, unstacker, fill_value, new_placement):
         # ExtensionArray-safe unstack.
         # We override ObjectBlock._unstack, which unstacks directly on the
diff --git a/pandas/tests/extension/base/methods.py b/pandas/tests/extension/base/methods.py
index 04290319bc592..0260e31786ce3 100644
--- a/pandas/tests/extension/base/methods.py
+++ b/pandas/tests/extension/base/methods.py
@@ -422,14 +422,19 @@ def test_repeat_raises(self, data, repeats, kwargs, error, msg, use_numpy):
             else:
                 data.repeat(repeats, **kwargs)
 
-    def test_equals(self, data, na_value):
+    def test_equals(self, data, na_value, as_series):
         data2 = type(data)._from_sequence([data[0]] * len(data), dtype=data.dtype)
         data_na = type(data)._from_sequence([na_value] * len(data), dtype=data.dtype)
 
+        if as_series:
+            data = pd.Series(data)
+            data2 = pd.Series(data2)
+            data_na = pd.Series(data_na)
+
         assert data.equals(data) is True
         assert data.equals(data.copy()) is True
 
-        # other data
+        # unequal other data
         assert data.equals(data2) is False
         assert data.equals(data_na) is False
 
@@ -442,19 +447,3 @@ def test_equals(self, data, na_value):
         # other types
         assert data.equals(None) is False
         assert data[[0]].equals(data[0]) is False
-
-        # TODO test series
-        # ser = pd.Series(data)
-        # smaller_ser = pd.Series(data[:5])
-        # na_ser = pd.Series(type(data)._from_sequence([na_value], dtype=data.dtype))
-
-        # assert ser.equals(ser)
-        # assert na_ser.equals(na_ser)
-
-        # assert not data.equals(na_value)
-        # assert not na_ser.equals(ser)
-        # assert not ser.equals(na_ser)
-        # assert not ser.equals(smaller_ser)
-        # assert not ser.equals(np.asarray(data))
-        # assert not ser.equals(0)
-        # assert not na_ser.equals(0)
diff --git a/pandas/tests/extension/json/test_json.py b/pandas/tests/extension/json/test_json.py
index b2b202039b8de..847be7515377c 100644
--- a/pandas/tests/extension/json/test_json.py
+++ b/pandas/tests/extension/json/test_json.py
@@ -248,7 +248,7 @@ def test_searchsorted(self, data_for_sorting):
         super().test_searchsorted(data_for_sorting)
 
     @pytest.mark.skip(reason="Can't compare dicts.")
-    def test_equals(self, data, na_value):
+    def test_equals(self, data, na_value, as_series):
         pass
 
 
diff --git a/pandas/tests/extension/test_numpy.py b/pandas/tests/extension/test_numpy.py
index aa2f9ea3257f4..cc959e86684e8 100644
--- a/pandas/tests/extension/test_numpy.py
+++ b/pandas/tests/extension/test_numpy.py
@@ -262,9 +262,9 @@ def test_diff(self, data, periods):
         return super().test_diff(data, periods)
 
     @skip_nested
-    def test_equals(self, data, na_value):
+    def test_equals(self, data, na_value, as_series):
         # Fails creating with _from_sequence
-        super().test_equals(data, na_value)
+        super().test_equals(data, na_value, as_series)
 
 
 @skip_nested
diff --git a/pandas/tests/extension/test_sparse.py b/pandas/tests/extension/test_sparse.py
index bd6b766f4bebb..8ede30a37a26a 100644
--- a/pandas/tests/extension/test_sparse.py
+++ b/pandas/tests/extension/test_sparse.py
@@ -316,9 +316,9 @@ def test_shift_0_periods(self, data):
         data._sparse_values[0] = data._sparse_values[1]
         assert result._sparse_values[0] != result._sparse_values[1]
 
-    def test_equals(self, data, na_value):
+    def test_equals(self, data, na_value, as_series):
         self._check_unsupported(data)
-        super().test_equals(data, na_value)
+        super().test_equals(data, na_value, as_series)
 
 
 class TestCasting(BaseSparseTests, base.BaseCastingTests):

From 8d052adab6476b5b13cba293486f234a5a3f99e6 Mon Sep 17 00:00:00 2001
From: Joris Van den Bossche <jorisvandenbossche@gmail.com>
Date: Sat, 2 May 2020 09:56:03 +0200
Subject: [PATCH 10/15] feedback: docs, whatsnew, dataframe test, strict dtype
 test

---
 doc/source/whatsnew/v1.1.0.rst                 |  1 +
 pandas/_testing.py                             |  4 +++-
 pandas/core/arrays/base.py                     | 12 ++++++++++--
 pandas/tests/arrays/integer/test_comparison.py | 10 ++++++++++
 pandas/tests/extension/base/methods.py         | 13 ++++++++-----
 pandas/tests/extension/test_numpy.py           |  5 +++--
 pandas/tests/extension/test_sparse.py          |  5 +++--
 7 files changed, 38 insertions(+), 12 deletions(-)

diff --git a/doc/source/whatsnew/v1.1.0.rst b/doc/source/whatsnew/v1.1.0.rst
index 4ad186d0ea6ea..cdc631b764365 100644
--- a/doc/source/whatsnew/v1.1.0.rst
+++ b/doc/source/whatsnew/v1.1.0.rst
@@ -150,6 +150,7 @@ Other enhancements
   such as ``dict`` and ``list``, mirroring the behavior of :meth:`DataFrame.update` (:issue:`33215`)
 - :meth:`~pandas.core.groupby.GroupBy.transform` and :meth:`~pandas.core.groupby.GroupBy.aggregate` has gained ``engine`` and ``engine_kwargs`` arguments that supports executing functions with ``Numba`` (:issue:`32854`, :issue:`33388`)
 - :meth:`~pandas.core.resample.Resampler.interpolate` now supports SciPy interpolation method :class:`scipy.interpolate.CubicSpline` as method ``cubicspline`` (:issue:`33670`)
+- The ``ExtensionArray`` class has now an ``equals`` method, similarly to ``Series.equals()`` (:issue:`27081`).
 -
 
 .. ---------------------------------------------------------------------------
diff --git a/pandas/_testing.py b/pandas/_testing.py
index eb4eb86c78b2d..1d105ebf0e1af 100644
--- a/pandas/_testing.py
+++ b/pandas/_testing.py
@@ -1490,7 +1490,9 @@ def box_expected(expected, box_cls, transpose=True):
     -------
     subclass of box_cls
     """
-    if box_cls is pd.Index:
+    if box_cls is pd.array:
+        expected = pd.array(expected)
+    elif box_cls is pd.Index:
         expected = pd.Index(expected)
     elif box_cls is pd.Series:
         expected = pd.Series(expected)
diff --git a/pandas/core/arrays/base.py b/pandas/core/arrays/base.py
index 6620357402434..63e041a4dfa59 100644
--- a/pandas/core/arrays/base.py
+++ b/pandas/core/arrays/base.py
@@ -335,13 +335,19 @@ def __iter__(self):
         for i in range(len(self)):
             yield self[i]
 
-    def __eq__(self, other: Any) -> Union[np.ndarray, "ExtensionArray"]:
+    def __eq__(self, other: Any) -> ArrayLike:
         """
         Return for `self == other` (element-wise equality).
         """
+        # Implementer note: this should return a boolean numpy ndarray or
+        # a boolean ExtensionArray.
+        # When `other` is one of Series, Index, or DataFrame, this method should
+        # return NotImplemented (to ensure that those objects are responsible for
+        # first unpacking the arrays, and then dispatch the operation to the
+        # underlying arrays)
         raise AbstractMethodError(self)
 
-    def __ne__(self, other: Any) -> Union[np.ndarray, "ExtensionArray"]:
+    def __ne__(self, other: Any) -> ArrayLike:
         """
         Return for `self != other` (element-wise in-equality).
         """
@@ -713,6 +719,8 @@ def equals(self, other: "ExtensionArray") -> bool:
         """
         if not type(self) == type(other):
             return False
+        elif not self.dtype == other.dtype:
+            return False
         elif not len(self) == len(other):
             return False
         else:
diff --git a/pandas/tests/arrays/integer/test_comparison.py b/pandas/tests/arrays/integer/test_comparison.py
index d76ed2c21ca0e..1767250af09b0 100644
--- a/pandas/tests/arrays/integer/test_comparison.py
+++ b/pandas/tests/arrays/integer/test_comparison.py
@@ -104,3 +104,13 @@ def test_compare_to_int(self, any_nullable_int_dtype, all_compare_operators):
         expected[s2.isna()] = pd.NA
 
         self.assert_series_equal(result, expected)
+
+
+def test_equals():
+    # GH-30652
+    # equals is generally tested in /tests/extension/base/methods, but this
+    # specifically tests that two arrays of the same class but different dtype
+    # do not evaluate equal
+    a1 = pd.array([1, 2, None], dtype="Int64")
+    a2 = pd.array([1, 2, None], dtype="Int32")
+    assert a1.equals(a2) is False
diff --git a/pandas/tests/extension/base/methods.py b/pandas/tests/extension/base/methods.py
index 0260e31786ce3..4a6d827b36b02 100644
--- a/pandas/tests/extension/base/methods.py
+++ b/pandas/tests/extension/base/methods.py
@@ -422,14 +422,17 @@ def test_repeat_raises(self, data, repeats, kwargs, error, msg, use_numpy):
             else:
                 data.repeat(repeats, **kwargs)
 
-    def test_equals(self, data, na_value, as_series):
+    @pytest.mark.parametrize("box", [pd.array, pd.Series, pd.DataFrame])
+    def test_equals(self, data, na_value, as_series, box):
         data2 = type(data)._from_sequence([data[0]] * len(data), dtype=data.dtype)
         data_na = type(data)._from_sequence([na_value] * len(data), dtype=data.dtype)
 
-        if as_series:
-            data = pd.Series(data)
-            data2 = pd.Series(data2)
-            data_na = pd.Series(data_na)
+        data = tm.box_expected(data, box, transpose=False)
+        data2 = tm.box_expected(data2, box, transpose=False)
+        data_na = tm.box_expected(data_na, box, transpose=False)
+
+        # we are asserting with `is True/False` explicitly, to test that the
+        # result is an actual Python bool, and not something "truthy"
 
         assert data.equals(data) is True
         assert data.equals(data.copy()) is True
diff --git a/pandas/tests/extension/test_numpy.py b/pandas/tests/extension/test_numpy.py
index cc959e86684e8..8e2a3a4a2c784 100644
--- a/pandas/tests/extension/test_numpy.py
+++ b/pandas/tests/extension/test_numpy.py
@@ -262,9 +262,10 @@ def test_diff(self, data, periods):
         return super().test_diff(data, periods)
 
     @skip_nested
-    def test_equals(self, data, na_value, as_series):
+    @pytest.mark.parametrize("box", [pd.array, pd.Series, pd.DataFrame])
+    def test_equals(self, data, na_value, as_series, box):
         # Fails creating with _from_sequence
-        super().test_equals(data, na_value, as_series)
+        super().test_equals(data, na_value, as_series, box)
 
 
 @skip_nested
diff --git a/pandas/tests/extension/test_sparse.py b/pandas/tests/extension/test_sparse.py
index 8ede30a37a26a..e59b3f0600867 100644
--- a/pandas/tests/extension/test_sparse.py
+++ b/pandas/tests/extension/test_sparse.py
@@ -316,9 +316,10 @@ def test_shift_0_periods(self, data):
         data._sparse_values[0] = data._sparse_values[1]
         assert result._sparse_values[0] != result._sparse_values[1]
 
-    def test_equals(self, data, na_value, as_series):
+    @pytest.mark.parametrize("box", [pd.array, pd.Series, pd.DataFrame])
+    def test_equals(self, data, na_value, as_series, box):
         self._check_unsupported(data)
-        super().test_equals(data, na_value, as_series)
+        super().test_equals(data, na_value, as_series, box)
 
 
 class TestCasting(BaseSparseTests, base.BaseCastingTests):

From 9ee034e4794dbf29410d34a1d2c3df8858cdb990 Mon Sep 17 00:00:00 2001
From: Joris Van den Bossche <jorisvandenbossche@gmail.com>
Date: Sat, 2 May 2020 09:58:36 +0200
Subject: [PATCH 11/15] add to reference docs

---
 doc/source/reference/extensions.rst | 1 +
 1 file changed, 1 insertion(+)

diff --git a/doc/source/reference/extensions.rst b/doc/source/reference/extensions.rst
index 4c0763e091b75..fe4113d100abf 100644
--- a/doc/source/reference/extensions.rst
+++ b/doc/source/reference/extensions.rst
@@ -45,6 +45,7 @@ objects.
       api.extensions.ExtensionArray.copy
       api.extensions.ExtensionArray.view
       api.extensions.ExtensionArray.dropna
+      api.extensions.ExtensionArray.equals
       api.extensions.ExtensionArray.factorize
       api.extensions.ExtensionArray.fillna
       api.extensions.ExtensionArray.isna

From 38501e60c0c2ca159fc868742fcdc8ed01ec4443 Mon Sep 17 00:00:00 2001
From: Joris Van den Bossche <jorisvandenbossche@gmail.com>
Date: Sat, 2 May 2020 10:12:54 +0200
Subject: [PATCH 12/15] remove IntervalArray.__ne__

---
 pandas/core/arrays/interval.py     | 3 ---
 pandas/tests/extension/base/ops.py | 6 ++++++
 2 files changed, 6 insertions(+), 3 deletions(-)

diff --git a/pandas/core/arrays/interval.py b/pandas/core/arrays/interval.py
index 66faca29670cb..8cac909b70802 100644
--- a/pandas/core/arrays/interval.py
+++ b/pandas/core/arrays/interval.py
@@ -606,9 +606,6 @@ def __eq__(self, other):
 
         return result
 
-    def __ne__(self, other):
-        return ~self.__eq__(other)
-
     def fillna(self, value=None, method=None, limit=None):
         """
         Fill NA/NaN values using the specified method.
diff --git a/pandas/tests/extension/base/ops.py b/pandas/tests/extension/base/ops.py
index e446ff8178226..188893c8b067c 100644
--- a/pandas/tests/extension/base/ops.py
+++ b/pandas/tests/extension/base/ops.py
@@ -174,6 +174,12 @@ def test_direct_arith_with_series_returns_not_implemented(self, data):
         else:
             raise pytest.skip(f"{type(data).__name__} does not implement __eq__")
 
+        if hasattr(data, "__ne__"):
+            result = data.__ne__(other)
+            assert result is NotImplemented
+        else:
+            raise pytest.skip(f"{type(data).__name__} does not implement __ne__")
+
 
 class BaseUnaryOpsTests(BaseOpsUtil):
     def test_invert(self, data):

From dccec7fcca1c3038e8a0211c443adcdfd3812332 Mon Sep 17 00:00:00 2001
From: Joris Van den Bossche <jorisvandenbossche@gmail.com>
Date: Tue, 5 May 2020 13:49:11 +0200
Subject: [PATCH 13/15] type ignore following mypy issue (mypy/2783)

---
 pandas/core/arrays/base.py | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/pandas/core/arrays/base.py b/pandas/core/arrays/base.py
index 63e041a4dfa59..84e1e6187482b 100644
--- a/pandas/core/arrays/base.py
+++ b/pandas/core/arrays/base.py
@@ -335,7 +335,7 @@ def __iter__(self):
         for i in range(len(self)):
             yield self[i]
 
-    def __eq__(self, other: Any) -> ArrayLike:
+    def __eq__(self, other: Any) -> ArrayLike:  # type: ignore[override] # NOQA
         """
         Return for `self == other` (element-wise equality).
         """
@@ -347,7 +347,7 @@ def __eq__(self, other: Any) -> ArrayLike:
         # underlying arrays)
         raise AbstractMethodError(self)
 
-    def __ne__(self, other: Any) -> ArrayLike:
+    def __ne__(self, other: Any) -> ArrayLike:  # type: ignore[override] # NOQA
         """
         Return for `self != other` (element-wise in-equality).
         """

From b8be8589c962453f5639d48002aad79c522eaf5c Mon Sep 17 00:00:00 2001
From: Joris Van den Bossche <jorisvandenbossche@gmail.com>
Date: Thu, 7 May 2020 22:23:13 +0200
Subject: [PATCH 14/15] try again without type: ignore

---
 pandas/core/arrays/base.py | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/pandas/core/arrays/base.py b/pandas/core/arrays/base.py
index 00becfd43adc2..1761b49d77165 100644
--- a/pandas/core/arrays/base.py
+++ b/pandas/core/arrays/base.py
@@ -335,7 +335,7 @@ def __iter__(self):
         for i in range(len(self)):
             yield self[i]
 
-    def __eq__(self, other: Any) -> ArrayLike:  # type: ignore[override] # NOQA
+    def __eq__(self, other: Any) -> ArrayLike:
         """
         Return for `self == other` (element-wise equality).
         """
@@ -347,7 +347,7 @@ def __eq__(self, other: Any) -> ArrayLike:  # type: ignore[override] # NOQA
         # underlying arrays)
         raise AbstractMethodError(self)
 
-    def __ne__(self, other: Any) -> ArrayLike:  # type: ignore[override] # NOQA
+    def __ne__(self, other: Any) -> ArrayLike:
         """
         Return for `self != other` (element-wise in-equality).
         """

From 4c7273f7c8d938668d64f27de2021ee2343858da Mon Sep 17 00:00:00 2001
From: Joris Van den Bossche <jorisvandenbossche@gmail.com>
Date: Fri, 8 May 2020 13:10:12 +0200
Subject: [PATCH 15/15] updates

---
 doc/source/whatsnew/v1.1.0.rst  | 3 ++-
 pandas/core/arrays/base.py      | 7 +++++--
 pandas/core/internals/blocks.py | 2 --
 3 files changed, 7 insertions(+), 5 deletions(-)

diff --git a/doc/source/whatsnew/v1.1.0.rst b/doc/source/whatsnew/v1.1.0.rst
index 351e3c7ad4ce9..3ce0db2cf38d0 100644
--- a/doc/source/whatsnew/v1.1.0.rst
+++ b/doc/source/whatsnew/v1.1.0.rst
@@ -150,7 +150,8 @@ Other enhancements
   such as ``dict`` and ``list``, mirroring the behavior of :meth:`DataFrame.update` (:issue:`33215`)
 - :meth:`~pandas.core.groupby.GroupBy.transform` and :meth:`~pandas.core.groupby.GroupBy.aggregate` has gained ``engine`` and ``engine_kwargs`` arguments that supports executing functions with ``Numba`` (:issue:`32854`, :issue:`33388`)
 - :meth:`~pandas.core.resample.Resampler.interpolate` now supports SciPy interpolation method :class:`scipy.interpolate.CubicSpline` as method ``cubicspline`` (:issue:`33670`)
-- The ``ExtensionArray`` class has now an ``equals`` method, similarly to ``Series.equals()`` (:issue:`27081`).
+- The ``ExtensionArray`` class has now an :meth:`~pandas.arrays.ExtensionArray.equals`
+  method, similarly to :meth:`Series.equals` (:issue:`27081`).
 -
 
 .. ---------------------------------------------------------------------------
diff --git a/pandas/core/arrays/base.py b/pandas/core/arrays/base.py
index 1761b49d77165..0c5634a932e12 100644
--- a/pandas/core/arrays/base.py
+++ b/pandas/core/arrays/base.py
@@ -706,16 +706,19 @@ def equals(self, other: "ExtensionArray") -> bool:
         """
         Return if another array is equivalent to this array.
 
+        Equivalent means that both arrays have the same shape and dtype, and
+        all values compare equal. Missing values in the same location are
+        considered equal (in contrast with normal equality).
+
         Parameters
         ----------
-        other: ExtensionArray
+        other : ExtensionArray
             Array to compare to this Array.
 
         Returns
         -------
         boolean
             Whether the arrays are equivalent.
-
         """
         if not type(self) == type(other):
             return False
diff --git a/pandas/core/internals/blocks.py b/pandas/core/internals/blocks.py
index c1e0fa7237185..d22adf2aaf179 100644
--- a/pandas/core/internals/blocks.py
+++ b/pandas/core/internals/blocks.py
@@ -1865,8 +1865,6 @@ def where(
         return [self.make_block_same_class(result, placement=self.mgr_locs)]
 
     def equals(self, other) -> bool:
-        if self.dtype != other.dtype or self.shape != other.shape:
-            return False
         return self.values.equals(other.values)
 
     def _unstack(self, unstacker, fill_value, new_placement):