From a12da2c86bc6b8a7f8f9b5016eb3e6abb4dde1b7 Mon Sep 17 00:00:00 2001
From: jreback <jeff@reback.net>
Date: Fri, 9 Aug 2013 09:40:28 -0400
Subject: [PATCH] BUG: GH4516 Fixed issue with sorting a duplicate multi-index
 that has multiple dtypes

---
 doc/source/release.rst          |  1 +
 pandas/core/frame.py            |  9 ++++++---
 pandas/core/index.py            | 13 +++++++++++--
 pandas/tests/test_multilevel.py | 12 ++++++++++++
 4 files changed, 30 insertions(+), 5 deletions(-)

diff --git a/doc/source/release.rst b/doc/source/release.rst
index 95ce03a858570..769b47b18db08 100644
--- a/doc/source/release.rst
+++ b/doc/source/release.rst
@@ -135,6 +135,7 @@ pandas 0.13
   - Raise on set indexing with a Panel and a Panel as a value which needs alignment (:issue:`3777`)
   - frozenset objects now raise in the ``Series`` constructor (:issue:`4482`,
     :issue:`4480`)
+  - Fixed issue with sorting a duplicate multi-index that has multiple dtypes (:issue:`4516`)
 
 pandas 0.12
 ===========
diff --git a/pandas/core/frame.py b/pandas/core/frame.py
index 902a6c736b569..0f3bcb32f7287 100644
--- a/pandas/core/frame.py
+++ b/pandas/core/frame.py
@@ -3304,10 +3304,13 @@ def sortlevel(self, level=0, axis=0, ascending=True, inplace=False):
         new_axis, indexer = the_axis.sortlevel(level, ascending=ascending)
 
         if self._is_mixed_type and not inplace:
-            if axis == 0:
-                return self.reindex(index=new_axis)
+            ax = 'index' if axis == 0 else 'columns'
+
+            if new_axis.is_unique:
+                d = { ax : new_axis }
             else:
-                return self.reindex(columns=new_axis)
+                d = { ax : indexer, 'takeable' : True }
+            return self.reindex(**d)
 
         if inplace:
             if axis == 1:
diff --git a/pandas/core/index.py b/pandas/core/index.py
index 5175e01d116c0..33ea4d25bc7dc 100644
--- a/pandas/core/index.py
+++ b/pandas/core/index.py
@@ -2165,8 +2165,17 @@ def reindex(self, target, method=None, level=None, limit=None,
             if self.equals(target):
                 indexer = None
             else:
-                indexer = self.get_indexer(target, method=method,
-                                           limit=limit)
+                if self.is_unique:
+                    indexer = self.get_indexer(target, method=method,
+                                               limit=limit)
+                else:
+                    if takeable:
+                        if method is not None or limit is not None:
+                            raise ValueError("cannot do a takeable reindex with "
+                                             "with a method or limit")
+                        return self[target], target
+
+                    raise Exception("cannot handle a non-takeable non-unique multi-index!")
 
         if not isinstance(target, MultiIndex):
             if indexer is None:
diff --git a/pandas/tests/test_multilevel.py b/pandas/tests/test_multilevel.py
index d54fc32b6efa6..7379bf5d148dc 100644
--- a/pandas/tests/test_multilevel.py
+++ b/pandas/tests/test_multilevel.py
@@ -1828,6 +1828,18 @@ def test_duplicate_groupby_issues(self):
         result = s.groupby(s.index).first()
         self.assertEquals(len(result), 3)
 
+    def test_duplicate_mi(self):
+        # GH 4516
+        df = DataFrame([['foo','bar',1.0,1],['foo','bar',2.0,2],['bah','bam',3.0,3],
+                        ['bah','bam',4.0,4],['foo','bar',5.0,5],['bah','bam',6.0,6]],
+                       columns=list('ABCD'))
+        df = df.set_index(['A','B'])
+        df = df.sortlevel(0)
+        result = df.loc[('foo','bar')]
+        expected = DataFrame([['foo','bar',1.0,1],['foo','bar',2.0,2],['foo','bar',5.0,5]],
+                             columns=list('ABCD')).set_index(['A','B'])
+        assert_frame_equal(result,expected)
+
     def test_multiindex_set_index(self):
         # segfault in #3308
         d = {'t1': [2, 2.5, 3], 't2': [4, 5, 6]}