From c404c4373049a4e457fa4051e2b386a9f146df65 Mon Sep 17 00:00:00 2001
From: jreback <jeff@reback.net>
Date: Wed, 18 Jun 2014 17:37:09 -0400
Subject: [PATCH] BUG: Bug in timeops with non-aligned Series (GH7500)

---
 doc/source/v0.14.1.txt      |  4 ++--
 pandas/core/ops.py          | 12 ++++++++++--
 pandas/tests/test_series.py | 18 ++++++++++++++++++
 3 files changed, 30 insertions(+), 4 deletions(-)

diff --git a/doc/source/v0.14.1.txt b/doc/source/v0.14.1.txt
index c1e5877d09004..930ba13bef122 100644
--- a/doc/source/v0.14.1.txt
+++ b/doc/source/v0.14.1.txt
@@ -165,10 +165,10 @@ Bug Fixes
 ~~~~~~~~~
 
 
+- Bug in timeops with non-aligned Series (:issue:`7500`)
 
 
-
-- Bug in ``value_counts`` where ``NaT`` did not qualify as missing (``NaN``) (:issue:`7423`) 
+- Bug in ``value_counts`` where ``NaT`` did not qualify as missing (``NaN``) (:issue:`7423`)
 
 
 
diff --git a/pandas/core/ops.py b/pandas/core/ops.py
index 0f19634cb5a38..780edec6ea25b 100644
--- a/pandas/core/ops.py
+++ b/pandas/core/ops.py
@@ -245,6 +245,12 @@ class _TimeOp(object):
     def __init__(self, left, right, name):
         self.name = name
 
+        # need to make sure that we are aligning the data
+        if isinstance(left, pd.Series) and isinstance(right, pd.Series):
+            left, right = left.align(right)
+
+        self.left = left
+        self.right = right
         lvalues = self._convert_to_array(left, name=name)
         rvalues = self._convert_to_array(right, name=name, other=lvalues)
 
@@ -426,6 +432,7 @@ def maybe_convert_for_time_op(cls, left, right, name):
         is_datetime_lhs = com.is_datetime64_dtype(left)
         if not (is_datetime_lhs or is_timedelta_lhs):
             return None
+
         # rops are allowed. No need for special checks, just strip off
         # r part.
         if name.startswith('__r'):
@@ -463,6 +470,7 @@ def wrapper(left, right, name=name):
 
         if isinstance(right, pd.DataFrame):
             return NotImplemented
+
         time_converted = _TimeOp.maybe_convert_for_time_op(left, right, name)
 
         if time_converted is None:
@@ -472,8 +480,8 @@ def wrapper(left, right, name=name):
         elif time_converted == NotImplemented:
             return NotImplemented
         else:
-            lvalues = time_converted.lvalues
-            rvalues = time_converted.rvalues
+            left, right = time_converted.left, time_converted.right
+            lvalues, rvalues = time_converted.lvalues, time_converted.rvalues
             dtype = time_converted.dtype
             wrap_results = time_converted.wrap_results
 
diff --git a/pandas/tests/test_series.py b/pandas/tests/test_series.py
index 2e3a9d922bb47..eb2b53dff3879 100644
--- a/pandas/tests/test_series.py
+++ b/pandas/tests/test_series.py
@@ -2838,6 +2838,24 @@ def run_ops(ops, get_ser, test_ser):
         td1 + dt1
         dt1 + td1
 
+    def test_ops_datetimelike_align(self):
+        if _np_version_under1p7:
+            raise nose.SkipTest("timedelta broken in np < 1.7")
+
+        # GH 7500
+        # datetimelike ops need to align
+        dt = Series(date_range('2012-1-1', periods=3, freq='D'))
+        dt.iloc[2] = np.nan
+        dt2 = dt[::-1]
+
+        expected = Series([timedelta(0),timedelta(0),pd.NaT])
+
+        result = dt2-dt
+        assert_series_equal(result,expected)
+
+        result = (dt2.to_frame()-dt.to_frame())[0]
+        assert_series_equal(result,expected)
+
     def test_timedelta64_functions(self):
 
         from datetime import timedelta