ENH: Adding default implementation to ExtensionArray equals() and tests.

pandas-devGH-27081

Author: dwhu

pandas/core/arrays/base.py

@@ -105,7 +105,6 @@ class ExtensionArray:
     * _from_sequence
     * _from_factorized
     * __getitem__
-    * __eq__
     * __len__
     * dtype
     * nbytes
@@ -358,24 +357,28 @@ 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:
         """
         Whether the two arrays are not equivalent.
 
         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]:

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

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)

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)