From f97e36ad04d3b12d8dfe2e650bada5b849859b5a Mon Sep 17 00:00:00 2001
From: jreback <jeff@reback.net>
Date: Thu, 11 Apr 2013 17:46:23 -0400
Subject: [PATCH] BUG: ensure index casting works even in Int64Index

---
 RELEASE.rst                |  1 +
 pandas/core/index.py       |  5 +++++
 pandas/tests/test_frame.py | 11 +++++++++++
 3 files changed, 17 insertions(+)

diff --git a/RELEASE.rst b/RELEASE.rst
index a542a406fcfaa..9016a9efdcae3 100644
--- a/RELEASE.rst
+++ b/RELEASE.rst
@@ -293,6 +293,7 @@ pandas 0.11.0
   - fixed pretty priniting of sets (GH3294_)
   - Panel() and Panel.from_dict() now respects ordering when give OrderedDict (GH3303_)
   - DataFrame where with a datetimelike incorrectly selecting (GH3311_)
+  - Ensure index casts work even in Int64Index
 
 .. _GH3294: https://github.com/pydata/pandas/issues/3294
 .. _GH622: https://github.com/pydata/pandas/issues/622
diff --git a/pandas/core/index.py b/pandas/core/index.py
index aa0fd5b6b0351..5b10a2321a387 100644
--- a/pandas/core/index.py
+++ b/pandas/core/index.py
@@ -1332,6 +1332,11 @@ def inferred_type(self):
     def _constructor(self):
         return Int64Index
 
+    @cache_readonly
+    def _engine(self):
+        # property, for now, slow to look up
+        return self._engine_type(lambda: com._ensure_int64(self.values), len(self))
+
     @property
     def asi8(self):
         # do not cache or you'll create a memory leak
diff --git a/pandas/tests/test_frame.py b/pandas/tests/test_frame.py
index 5e5b24bb6734d..de0011185e35b 100644
--- a/pandas/tests/test_frame.py
+++ b/pandas/tests/test_frame.py
@@ -1836,6 +1836,17 @@ def test_set_index(self):
         self.assertRaises(Exception, setattr, self.mixed_frame, 'index',
                           idx[::2])
 
+    def test_set_index_cast(self):
+
+        # issue casting an index then set_index
+        df = DataFrame({'A' : [1.1,2.2,3.3], 'B' : [5.0,6.1,7.2]},
+                       index = [2010,2011,2012])
+        expected = df.ix[2010]
+        new_index = df.index.astype(np.int32)
+        df.index = new_index
+        result = df.ix[2010]
+        assert_series_equal(result,expected)
+
     def test_set_index2(self):
         df = DataFrame({'A': ['foo', 'foo', 'foo', 'bar', 'bar'],
                         'B': ['one', 'two', 'three', 'one', 'two'],