BUG: close #816, fix exception thrown on np.diff

Author: adamklein

RELEASE.rst

@@ -43,6 +43,7 @@ pandas 0.7.1
   - Fixed groupby corner case when passing dictionary grouper and as_index is
     False (#819)
   - Fixed bug whereby bool array sometimes had object dtype (#820)
+  - Fix exception thrown on np.diff (#816)
 
 pandas 0.7.0
 ============

pandas/core/series.py

@@ -369,6 +369,8 @@ def ix(self):
 
     def __getitem__(self, key):
         try:
+            if type(key) == tuple and len(key)==1:
+                key = key[0]
             return self.index.get_value(self, key)
         except InvalidIndexError:
             pass

pandas/tests/test_series.py

@@ -911,6 +911,11 @@ def test_cummax(self):
 
         self.assert_(np.array_equal(result, expected))
 
+    def test_npdiff(self):
+        s = Series(np.arange(5))
+        r = np.diff(s)
+        assert_series_equal(Series([nan, 0, 0, 0, nan]), r)
+
     def _check_stat_op(self, name, alternate, check_objects=False):
         from pandas import DateRange
         import pandas.core.nanops as nanops