From ce349d1e887213c18eb469ab4ce86597b5f72bd2 Mon Sep 17 00:00:00 2001
From: Ka Wo Chen <kawoc@tepper.cmu.edu>
Date: Sat, 22 Aug 2015 10:46:00 -0400
Subject: [PATCH] BUG: GH10885 where an edge case in date_range produces an
 extra timestamp

---
 doc/source/whatsnew/v0.17.0.txt        |  1 +
 pandas/tseries/index.py                |  6 ++++--
 pandas/tseries/tests/test_daterange.py | 12 ++++++++++++
 3 files changed, 17 insertions(+), 2 deletions(-)

diff --git a/doc/source/whatsnew/v0.17.0.txt b/doc/source/whatsnew/v0.17.0.txt
index d30b7875e44b7..cc8f135eb62b0 100644
--- a/doc/source/whatsnew/v0.17.0.txt
+++ b/doc/source/whatsnew/v0.17.0.txt
@@ -781,6 +781,7 @@ Bug Fixes
 - Bug in ``DatetimeIndex.take`` and ``TimedeltaIndex.take`` may not raise ``IndexError`` against invalid index (:issue:`10295`)
 - Bug in ``Series([np.nan]).astype('M8[ms]')``, which now returns ``Series([pd.NaT])`` (:issue:`10747`)
 - Bug in ``PeriodIndex.order`` reset freq (:issue:`10295`)
+- Bug in ``date_range`` when ``freq`` divides ``end`` as nanos (:issue:`10885`)
 - Bug in ``iloc`` allowing memory outside bounds of a Series to be accessed with negative integers (:issue:`10779`)
 - Bug in ``read_msgpack`` where encoding is not respected (:issue:`10580`)
 - Bug preventing access to the first index when using ``iloc`` with a list containing the appropriate negative integer (:issue:`10547`, :issue:`10779`)
diff --git a/pandas/tseries/index.py b/pandas/tseries/index.py
index 0525a29ef3fd0..c6c66a62b86b5 100644
--- a/pandas/tseries/index.py
+++ b/pandas/tseries/index.py
@@ -1,4 +1,5 @@
 # pylint: disable=E1101
+from __future__ import division
 import operator
 import warnings
 from datetime import time, datetime
@@ -1793,8 +1794,9 @@ def _generate_regular_range(start, end, periods, offset):
         stride = offset.nanos
         if periods is None:
             b = Timestamp(start).value
-            e = Timestamp(end).value
-            e += stride - e % stride
+            # cannot just use e = Timestamp(end) + 1 because arange breaks when
+            # stride is too large, see GH10887
+            e = b + (Timestamp(end).value - b)//stride * stride + stride//2
             # end.tz == start.tz by this point due to _generate implementation
             tz = start.tz
         elif start is not None:
diff --git a/pandas/tseries/tests/test_daterange.py b/pandas/tseries/tests/test_daterange.py
index 86e0f7162c545..42136c3433977 100644
--- a/pandas/tseries/tests/test_daterange.py
+++ b/pandas/tseries/tests/test_daterange.py
@@ -490,6 +490,18 @@ def test_years_only(self):
         self.assertEqual(dr[0], datetime(2014, 1, 31))
         self.assertEqual(dr[-1], datetime(2014, 12, 31))
 
+    def test_freq_divides_end_in_nanos(self):
+        # GH 10885
+        result_1 = date_range('2005-01-12 10:00', '2005-01-12 16:00',
+                              freq='345min')
+        result_2 = date_range('2005-01-13 10:00', '2005-01-13 16:00',
+                              freq='345min')
+        expected_1 = DatetimeIndex(['2005-01-12 10:00:00', '2005-01-12 15:45:00'],
+                                   dtype='datetime64[ns]', freq='345T', tz=None)
+        expected_2 = DatetimeIndex(['2005-01-13 10:00:00', '2005-01-13 15:45:00'],
+                                   dtype='datetime64[ns]', freq='345T', tz=None)
+        self.assertTrue(result_1.equals(expected_1))
+        self.assertTrue(result_2.equals(expected_2))
 
 class TestCustomDateRange(tm.TestCase):