BUG: reindex with axis=1 when setting Series to scalar location, close #1942

Author: wesm

README.rst

@@ -63,7 +63,7 @@ Dependencies
 ============
 
   * `NumPy <http://www.numpy.org>`__: 1.6.1 or higher
-  * `python-dateutil <http://labix.org/python-dateutil>`__ 1.5
+  * `python-dateutil <http://labix.org/python-dateutil>`__ 1.5 or higher
 
 Optional dependencies
 ~~~~~~~~~~~~~~~~~~~~~

pandas/core/indexing.py

@@ -147,9 +147,12 @@ def _align_series(self, indexer, ser):
                     return ser.reindex(new_ix).values
 
         elif np.isscalar(indexer):
-            if ser.index.equals(self.obj.index):
+            ax = self.obj._get_axis(1)
+
+            if ser.index.equals(ax):
                 return ser.values.copy()
-            return ser.reindex(self.obj.index).values
+
+            return ser.reindex(ax).values
 
         raise ValueError('Incompatible indexer with Series')
 

pandas/tests/test_frame.py

@@ -191,6 +191,12 @@ def test_getitem_setitem_ix_negative_integers(self):
         df = DataFrame(np.random.randn(8, 4))
         self.assert_(isnull(df.ix[:, [-1]].values).all())
 
+        # #1942
+        a = DataFrame(randn(20,2), index=[chr(x+65) for x in range(20)])
+        a.ix[-1] = a.ix[-2]
+
+        assert_series_equal(a.ix[-1], a.ix[-2])
+
     def test_getattr(self):
         tm.assert_series_equal(self.frame.A, self.frame['A'])
         self.assertRaises(AttributeError, getattr, self.frame,