BUG: period resampling bug when all values fall into a single bin. close #2070

Author: wesm

RELEASE.rst

@@ -106,6 +106,7 @@ pandas 0.10.1
   - Fix partial date parsing issue occuring only when code is run at EOM  (GH2618_)
   - Prevent MemoryError when using counting sort in sortlevel with
     high-cardinality MultiIndex objects (GH2684_)
+  - Fix Period resampling bug when all values fall into a single bin (GH2070_)
 
 **API Changes**
 
@@ -118,6 +119,7 @@ pandas 0.10.1
 
 .. _GH512: https://github.com/pydata/pandas/issues/512
 .. _GH1277: https://github.com/pydata/pandas/issues/1277
+.. _GH2070: https://github.com/pydata/pandas/issues/2070
 .. _GH2327: https://github.com/pydata/pandas/issues/2327
 .. _GH2585: https://github.com/pydata/pandas/issues/2585
 .. _GH2599: https://github.com/pydata/pandas/issues/2599

pandas/tseries/resample.py

@@ -249,7 +249,7 @@ def _resample_periods(self, obj):
 
         if is_subperiod(axlabels.freq, self.freq) or self.how is not None:
             # Downsampling
-            rng = np.arange(memb.values[0], memb.values[-1])
+            rng = np.arange(memb.values[0], memb.values[-1] + 1)
             bins = memb.searchsorted(rng, side='right')
             grouper = BinGrouper(bins, new_index)
 

pandas/tseries/tests/test_resample.py

@@ -972,6 +972,14 @@ def test_default_left_closed_label(self):
             assert_frame_equal(resampled, df.resample(to_freq, closed='left',
                                                       label='left'))
 
+    def test_all_values_single_bin(self):
+        # 2070
+        index = period_range(start="2012-01-01", end="2012-12-31", freq="M")
+        s = Series(np.random.randn(len(index)), index=index)
+
+        result = s.resample("A", how='mean')
+        tm.assert_almost_equal(result[0], s.mean())
+
 
 class TestTimeGrouper(unittest.TestCase):