ENH: implement EA.size (#32644)

Author: jbrockmendel

pandas/core/arrays/base.py

@@ -407,6 +407,13 @@ def shape(self) -> Tuple[int, ...]:
         """
         return (len(self),)
 
+    @property
+    def size(self) -> int:
+        """
+        The number of elements in the array.
+        """
+        return np.prod(self.shape)
+
     @property
     def ndim(self) -> int:
         """

pandas/tests/extension/base/interface.py

@@ -19,6 +19,9 @@ class BaseInterfaceTests(BaseExtensionTests):
     def test_len(self, data):
         assert len(data) == 100
 
+    def test_size(self, data):
+        assert data.size == 100
+
     def test_ndim(self, data):
         assert data.ndim == 1