Merge pull request #5125 from jtratner/fix-segfault-mi-isnull

BUG: Fix segfault on isnull(MultiIndex)

Author: jtratner

doc/source/release.rst

@@ -584,6 +584,8 @@ Bug Fixes
   - Made sure different locales are tested on travis-ci (:issue:`4918`). Also
     adds a couple of utilities for getting locales and setting locales with a
     context manager.
+  - Fixed segfault on ``isnull(MultiIndex)`` (now raises an error instead)
+    (:issue:`5123`, :issue:`5125`)
 
 pandas 0.12.0
 -------------

pandas/core/common.py

@@ -12,6 +12,7 @@
 from numpy.lib.format import read_array, write_array
 import numpy as np
 
+import pandas as pd
 import pandas.algos as algos
 import pandas.lib as lib
 import pandas.tslib as tslib
@@ -116,8 +117,10 @@ def isnull(obj):
 def _isnull_new(obj):
     if lib.isscalar(obj):
         return lib.checknull(obj)
-
-    if isinstance(obj, (ABCSeries, np.ndarray)):
+    # hack (for now) because MI registers as ndarray
+    elif isinstance(obj, pd.MultiIndex):
+        raise NotImplementedError("isnull is not defined for MultiIndex")
+    elif isinstance(obj, (ABCSeries, np.ndarray)):
         return _isnull_ndarraylike(obj)
     elif isinstance(obj, ABCGeneric):
         return obj.apply(isnull)
@@ -141,8 +144,10 @@ def _isnull_old(obj):
     '''
     if lib.isscalar(obj):
         return lib.checknull_old(obj)
-
-    if isinstance(obj, (ABCSeries, np.ndarray)):
+    # hack (for now) because MI registers as ndarray
+    elif isinstance(obj, pd.MultiIndex):
+        raise NotImplementedError("isnull is not defined for MultiIndex")
+    elif isinstance(obj, (ABCSeries, np.ndarray)):
         return _isnull_ndarraylike_old(obj)
     elif isinstance(obj, ABCGeneric):
         return obj.apply(_isnull_old)

pandas/tests/test_index.py

@@ -2314,6 +2314,13 @@ def test_slice_keep_name(self):
                                    names=['x', 'y'])
         self.assertEqual(x[1:].names, x.names)
 
+    def test_isnull_behavior(self):
+        # should not segfault GH5123
+        # NOTE: if MI representation changes, may make sense to allow
+        # isnull(MI)
+        with tm.assertRaises(NotImplementedError):
+            pd.isnull(self.index)
+
 
 def test_get_combined_index():
     from pandas.core.index import _get_combined_index