BUG: Correctly localize naive datetime strings with Series and datetimetztype (pandas-dev#17415) (pandas-dev#17603)

Author: mroeschke

doc/source/whatsnew/v0.23.0.txt

@@ -381,7 +381,7 @@ Conversion
 - Fixed bug where comparing :class:`DatetimeIndex` failed to raise ``TypeError`` when attempting to compare timezone-aware and timezone-naive datetimelike objects (:issue:`18162`)
 - Bug in :class:`DatetimeIndex` where the repr was not showing high-precision time values at the end of a day (e.g., 23:59:59.999999999) (:issue:`19030`)
 - Bug where dividing a scalar timedelta-like object with :class:`TimedeltaIndex` performed the reciprocal operation (:issue:`19125`)
--
+- Bug in localization of a naive, datetime string in a ``Series`` constructor with a ``datetime64[ns, tz]`` dtype (:issue:`174151`)
 
 Indexing
 ^^^^^^^^

pandas/core/dtypes/cast.py

@@ -20,7 +20,7 @@
  is_integer_dtype,
  is_datetime_or_timedelta_dtype,
  is_bool_dtype, is_scalar,
- _string_dtypes,
+ is_string_dtype, _string_dtypes,
  pandas_dtype,
  _ensure_int8, _ensure_int16,
  _ensure_int32, _ensure_int64,
@@ -1016,12 +1016,20 @@ def maybe_cast_to_datetime(value, dtype, errors='raise'):
  if is_datetime64:
  value = to_datetime(value, errors=errors)._values
  elif is_datetime64tz:
- # input has to be UTC at this point, so just
- # localize
- value = (to_datetime(value, errors=errors)
- .tz_localize('UTC')
- .tz_convert(dtype.tz)
- )
+ # The string check can be removed once issue #13712
+ # is solved. String data that is passed with a
+ # datetime64tz is assumed to be naive which should
+ # be localized to the timezone.
+ is_dt_string = is_string_dtype(value)
+ value = to_datetime(value, errors=errors)
+ if is_dt_string:
+ # Strings here are naive, so directly localize
+ value = value.tz_localize(dtype.tz)
+ else:
+ # Numeric values are UTC at this point,
+ # so localize and convert
+ value = (value.tz_localize('UTC')
+ .tz_convert(dtype.tz))
  elif is_timedelta64:
  value = to_timedelta(value, errors=errors)._values
  except (AttributeError, ValueError, TypeError):

pandas/tests/series/test_constructors.py

@@ -707,6 +707,14 @@ def test_constructor_with_datetime_tz(self):
  expected = Series(pd.DatetimeIndex(['NaT', 'NaT'], tz='US/Eastern'))
  assert_series_equal(s, expected)
 
+ @pytest.mark.parametrize('arg',
+ ['2013-01-01 00:00:00', pd.NaT, np.nan, None])
+ def test_constructor_with_naive_string_and_datetimetz_dtype(self, arg):
+ # GH 17415: With naive string
+ result = Series([arg], dtype='datetime64[ns, CET]')
+ expected = Series(pd.Timestamp(arg)).dt.tz_localize('CET')
+ assert_series_equal(result, expected)
+
  def test_construction_interval(self):
  # construction from interval & array of intervals
  index = IntervalIndex.from_breaks(np.arange(3), closed='right')