Fix bug where use of .ix[tuple(...)]=x fails to correctly check out of b...

doc/source/release.rst

@@ -84,6 +84,7 @@ Bug Fixes
   - Regresssion in handling of empty Series as indexers to Series  (:issue:`5877`)
   - Bug in internal caching, related to (:issue:`5727`)
   - Testing bug in reading json/msgpack from a non-filepath on windows under py3 (:issue:`5874`)
+  - Bug when assigning to .ix[tuple(...)] (:issue:`5896`)
 
 pandas 0.13.0
 -------------

pandas/core/indexing.py

@@ -903,7 +903,8 @@ def _convert_to_indexer(self, obj, axis=0, is_setter=False):
                     return {'key': obj}
 
                 # a positional
-                if obj >= len(self.obj) and not isinstance(labels, MultiIndex):
+                if (obj >= self.obj.shape[axis] and
+                        not isinstance(labels, MultiIndex)):
                     raise ValueError("cannot set by positional indexing with "
                                      "enlargement")
 

pandas/tests/test_indexing.py

@@ -2352,6 +2352,14 @@ def check_slicing_positional(index):
         #self.assertRaises(TypeError, lambda : s.iloc[2.0:5.0])
         #self.assertRaises(TypeError, lambda : s.iloc[2:5.0])
 
+    def test_set_ix_out_of_bounds_axis_0(self):
+        df = pd.DataFrame(randn(2, 5), index=["row%s" % i for i in range(2)], columns=["col%s" % i for i in range(5)])
+        self.assertRaises(ValueError, df.ix.__setitem__, (2, 0), 100)
+
+    def test_set_ix_out_of_bounds_axis_1(self):
+        df = pd.DataFrame(randn(5, 2), index=["row%s" % i for i in range(5)], columns=["col%s" % i for i in range(2)])
+        self.assertRaises(ValueError, df.ix.__setitem__, (0 , 2), 100)
+
 
 if __name__ == '__main__':
     import nose