BUG: .fillna() for datetime64 with tz is passing thru floats

closes #14872

Author: Rodolfo Fernandez <opensourceworkAR@users.noreply.github.com>

Closes #14905 from RodolfoRFR/pandas-14872-e and squashes the following commits:

18802b4 [Rodolfo Fernandez] added 'self' to test_dtype_utc function in pandas/tests/series/test_missing
e0c6c7c [Rodolfo Fernandez] added line to whatsnew v0.19.2 and test to test_missing.py in series folder
e4ba7e0 [Rodolfo Fernandez] removed all references to _DATELIKE_DTYPES from /pandas/core/missing.py
5d37ce8 [Rodolfo Fernandez] added is_datetime64tz_dtype and changed evaluation from 'values' to dtype
19eecb2 [Rodolfo Fernandez] fixed style errors using flake8
59b91a1 [Rodolfo Fernandez] test modified
5a59eac [Rodolfo Fernandez] test modified
bc68bf7 [Rodolfo Fernandez] test modified
ba83fc8 [Rodolfo Fernandez] test
b7358de [Rodolfo Fernandez] bug fixed

doc/source/whatsnew/v0.19.2.txt

@@ -47,6 +47,7 @@ Bug Fixes
 - Bug in ``pd.read_csv`` for the Python engine in which an unhelpful error message was being raised when multi-char delimiters were not being respected with quotes (:issue:`14582`)
 - Fix bugs (:issue:`14734`, :issue:`13654`) in ``pd.read_sas`` and ``pandas.io.sas.sas7bdat.SAS7BDATReader`` that caused problems when reading a SAS file incrementally.
 - Bug in ``pd.read_csv`` for the Python engine in which an unhelpful error message was being raised when ``skipfooter`` was not being respected by Python's CSV library (:issue:`13879`)
+- Bug in ``.fillna()`` in which timezone aware datetime64 values were incorrectly rounded (:issue:`14872`)
 
 
 - Bug in ``.groupby(..., sort=True)`` of a non-lexsorted MultiIndex when grouping with multiple levels (:issue:`14776`)

pandas/core/missing.py

@@ -10,9 +10,8 @@ import pandas.lib as lib
 from pandas.compat import range, string_types
 from pandas.types.common import (is_numeric_v_string_like,
                                  is_float_dtype, is_datetime64_dtype,
-                                 is_integer_dtype, _ensure_float64,
-                                 is_scalar,
-                                 _DATELIKE_DTYPES,
+                                 is_datetime64tz_dtype, is_integer_dtype,
+                                 _ensure_float64, is_scalar,
                                  needs_i8_conversion)
 from pandas.types.missing import isnull
 
@@ -450,7 +449,7 @@ def pad_1d(values, limit=None, mask=None, dtype=None):
     _method = None
     if is_float_dtype(values):
         _method = getattr(algos, 'pad_inplace_%s' % dtype.name, None)
-    elif dtype in _DATELIKE_DTYPES or is_datetime64_dtype(values):
+    elif is_datetime64_dtype(dtype) or is_datetime64tz_dtype(dtype):
         _method = _pad_1d_datetime
     elif is_integer_dtype(values):
         values = _ensure_float64(values)
@@ -475,7 +474,7 @@ def backfill_1d(values, limit=None, mask=None, dtype=None):
     _method = None
     if is_float_dtype(values):
         _method = getattr(algos, 'backfill_inplace_%s' % dtype.name, None)
-    elif dtype in _DATELIKE_DTYPES or is_datetime64_dtype(values):
+    elif is_datetime64_dtype(dtype) or is_datetime64tz_dtype(dtype):
         _method = _backfill_1d_datetime
     elif is_integer_dtype(values):
         values = _ensure_float64(values)
@@ -501,7 +500,7 @@ def pad_2d(values, limit=None, mask=None, dtype=None):
     _method = None
     if is_float_dtype(values):
         _method = getattr(algos, 'pad_2d_inplace_%s' % dtype.name, None)
-    elif dtype in _DATELIKE_DTYPES or is_datetime64_dtype(values):
+    elif is_datetime64_dtype(dtype) or is_datetime64tz_dtype(dtype):
         _method = _pad_2d_datetime
     elif is_integer_dtype(values):
         values = _ensure_float64(values)
@@ -531,7 +530,7 @@ def backfill_2d(values, limit=None, mask=None, dtype=None):
     _method = None
     if is_float_dtype(values):
         _method = getattr(algos, 'backfill_2d_inplace_%s' % dtype.name, None)
-    elif dtype in _DATELIKE_DTYPES or is_datetime64_dtype(values):
+    elif is_datetime64_dtype(dtype) or is_datetime64tz_dtype(dtype):
         _method = _backfill_2d_datetime
     elif is_integer_dtype(values):
         values = _ensure_float64(values)

pandas/tests/series/test_missing.py

@@ -1,7 +1,8 @@
 # coding=utf-8
 # pylint: disable-msg=E1101,W0612
 
-from datetime import timedelta
+import pytz
+from datetime import timedelta, datetime
 
 from numpy import nan
 import numpy as np
@@ -10,7 +11,6 @@ import pandas as pd
 from pandas import (Series, isnull, date_range,
                     MultiIndex, Index)
 from pandas.tseries.index import Timestamp
-
 from pandas.compat import range
 from pandas.util.testing import assert_series_equal
 import pandas.util.testing as tm
@@ -250,6 +250,24 @@ class TestSeriesMissingData(TestData, tm.TestCase):
             self.assert_series_equal(expected, result)
             self.assert_series_equal(pd.isnull(s), null_loc)
 
+    def test_datetime64tz_fillna_round_issue(self):
+        # GH 14872
+
+        data = pd.Series([pd.NaT, pd.NaT,
+                          datetime(2016, 12, 12, 22, 24, 6, 100001,
+                                   tzinfo=pytz.utc)])
+
+        filled = data.fillna(method='bfill')
+
+        expected = pd.Series([datetime(2016, 12, 12, 22, 24, 6,
+                                       100001, tzinfo=pytz.utc),
+                              datetime(2016, 12, 12, 22, 24, 6,
+                                       100001, tzinfo=pytz.utc),
+                              datetime(2016, 12, 12, 22, 24, 6,
+                                       100001, tzinfo=pytz.utc)])
+
+        assert_series_equal(filled, expected)
+
     def test_fillna_int(self):
         s = Series(np.random.randint(-100, 100, 50))
         s.fillna(method='ffill', inplace=True)
@@ -908,7 +926,6 @@ class TestSeriesInterpolateData(TestData, tm.TestCase):
                           index=pd.to_timedelta([1, 2, 4]))
         assert_series_equal(result, expected)
 
-
 if __name__ == '__main__':
     import nose
     nose.runmodule(argv=[__file__, '-vvs', '-x', '--pdb', '--pdb-failure'],

pandas/types/common.py

@@ -22,6 +22,7 @@ _POSSIBLY_CAST_DTYPES = set([np.dtype(t).name
 _NS_DTYPE = np.dtype('M8[ns]')
 _TD_DTYPE = np.dtype('m8[ns]')
 _INT64_DTYPE = np.dtype(np.int64)
+
 _DATELIKE_DTYPES = set([np.dtype(t)
                         for t in ['M8[ns]', '<M8[ns]', '>M8[ns]',
                                   'm8[ns]', '<m8[ns]', '>m8[ns]']])