Merge branch 'iadd' of https://github.com/d10genes/pandas into d10genes-iadd

Conflicts:
	doc/source/release.rst

Author: jreback

doc/source/release.rst

@@ -161,7 +161,7 @@ Improvements to existing features
     :issue:`4998`)
   - ``to_dict`` now takes ``records`` as a possible outtype.  Returns an array
     of column-keyed dictionaries. (:issue:`4936`)
-  - ``tz_localize`` can infer a fall daylight savings transition based on the 
+  - ``tz_localize`` can infer a fall daylight savings transition based on the
     structure of unlocalized data (:issue:`4230`)
   - DatetimeIndex is now in the API documentation
 
@@ -244,6 +244,12 @@ API Changes
       views (similar to ``np.may_share_memory`` but no false positives, and
       changes on ``levels`` and ``labels`` setting on ``MultiIndex``).
       (:issue:`4859` , :issue:`4909`)
+    - Aliased ``__iadd__`` to ``__add__``. (:issue:`4996`)
+    - Added ``is_`` method to ``Index`` that allows fast equality comparison of
+      views (similar to ``np.may_share_memory`` but no false positives, and
+      changes on ``levels`` and ``labels`` setting on ``MultiIndex``).
+      (:issue:`4859`, :issue:`4909`)
+
   - Infer and downcast dtype if ``downcast='infer'`` is passed to ``fillna/ffill/bfill`` (:issue:`4604`)
   - ``__nonzero__`` for all NDFrame objects, will now raise a ``ValueError``, this reverts back to (:issue:`1073`, :issue:`4633`)
     behavior. Add ``.bool()`` method to ``NDFrame`` objects to facilitate evaluating of single-element boolean Series

pandas/core/index.py

@@ -833,6 +833,7 @@ def __add__(self, other):
         else:
             return Index(self.view(np.ndarray) + other)
 
+    __iadd__ = __add__
     __eq__ = _indexOp('__eq__')
     __ne__ = _indexOp('__ne__')
     __lt__ = _indexOp('__lt__')

pandas/tests/test_index.py

@@ -407,6 +407,14 @@ def test_add_string(self):
         self.assert_('a' not in index2)
         self.assert_('afoo' in index2)
 
+    def test_iadd_string(self):
+        index = pd.Index(['a', 'b', 'c'])
+        # doesn't fail test unless there is a check before `+=`
+        self.assert_('a' in index)
+
+        index += '_x'
+        self.assert_('a_x' in index)
+
     def test_diff(self):
         first = self.strIndex[5:20]
         second = self.strIndex[:10]