Merge pull request #6761 from TomAugspurger/lazy-iteritems

BUG: Series.iteritems should be lazy

Author: Tom Augspurger

doc/source/release.rst

@@ -151,7 +151,7 @@ API Changes
 - ``DataFrame.sort`` now places NaNs at the beginning or end of the sort according to the ``na_position`` parameter. (:issue:`3917`)
 
 - all offset operations now return ``Timestamp`` types (rather than datetime), Business/Week frequencies were incorrect (:issue:`4069`)
-
+- ``Series.iteritems()`` is now lazy (returns an iterator rather than a list). This was the documented behavior prior to 0.14. (:issue:`6760`)
 
 Deprecations
 ~~~~~~~~~~~~

doc/source/v0.14.0.txt

@@ -196,6 +196,8 @@ API changes
     covs = rolling_cov(df[['A','B','C']], df[['B','C','D']], 5, pairwise=True)
     covs[df.index[-1]]
 
+- ``Series.iteritems()`` is now lazy (returns an iterator rather than a list). This was the documented behavior prior to 0.14. (:issue:`6760`)
+
 
 MultiIndexing Using Slicers
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~

pandas/core/series.py

@@ -959,7 +959,7 @@ def iteritems(self):
         """
         Lazily iterate over (index, value) tuples
         """
-        return lzip(iter(self.index), iter(self))
+        return zip(iter(self.index), iter(self))
 
     if compat.PY3:  # pragma: no cover
         items = iteritems

pandas/tests/test_series.py

@@ -1808,6 +1808,9 @@ def test_iteritems(self):
         for idx, val in compat.iteritems(self.ts):
             self.assertEqual(val, self.ts[idx])
 
+        # assert is lazy (genrators don't define __getslice__, lists do)
+        self.assertFalse(hasattr(self.series.iteritems(), '__getslice__'))
+
     def test_sum(self):
         self._check_stat_op('sum', np.sum)