Move the method size to ExtensionArray.

Signed-off-by: HE, Tao <[email protected]>

Author: sighingnow

doc/source/whatsnew/v0.24.2.rst

@@ -31,15 +31,13 @@ Fixed Regressions
 - Fixed regression in ``IntervalDtype`` construction where passing an incorrect string with 'Interval' as a prefix could result in a ``RecursionError``. (:issue:`25338`)
 - Fixed regression in :class:`Categorical`, where constructing it from a categorical ``Series`` and an explicit ``categories=`` that differed from that in the ``Series`` created an invalid object which could trigger segfaults. (:issue:`25318`)
 - Fixed pip installing from source into an environment without NumPy (:issue:`25193`)
-- Fixed regression in :meth:`Series.resample` when underlying array is :class:`IntegerArray`. (:issue:`25580`)
 
 .. _whatsnew_0242.enhancements:
 
 Enhancements
 ^^^^^^^^^^^^
 
--
--
+- Add :meth:`IntegerArray.size` to return the number of elements in :class:`ExtensionArray` (:issue:`25580`)
 
 .. _whatsnew_0242.bug_fixes:
 

pandas/core/arrays/base.py

@@ -46,6 +46,7 @@ class ExtensionArray(object):
     * __len__
     * dtype
     * nbytes
+    * size
     * isna
     * take
     * copy
@@ -318,6 +319,18 @@ def nbytes(self):
         # on the number of bytes needed.
         raise AbstractMethodError(self)
 
+    @property
+    def size(self):
+        # type: () -> int
+        """
+        The number of elements in this array.
+
+        Returns
+        -------
+        size : int
+        """
+        return len(self)
+
     # ------------------------------------------------------------------------
     # Additional Methods
     # ------------------------------------------------------------------------

pandas/core/arrays/integer.py

@@ -400,10 +400,6 @@ def __setitem__(self, key, value):
     def __len__(self):
         return len(self._data)
 
-    @property
-    def size(self):
-        return self._data.size
-
     @property
     def nbytes(self):
         return self._data.nbytes + self._mask.nbytes