BUG: DataFrame with scalar tzaware Timestamp (#44518) (#44546)

Author: jbrockmendel

pandas/core/arrays/datetimes.py

@@ -2067,8 +2067,13 @@ def sequence_to_dt64ns(
  )
  if tz and inferred_tz:
  # two timezones: convert to intended from base UTC repr
- data = tzconversion.tz_convert_from_utc(data.view("i8"), tz)
- data = data.view(DT64NS_DTYPE)
+ if data.dtype == "i8":
+ # GH#42505
+ # by convention, these are _already_ UTC, e.g
+ return data.view(DT64NS_DTYPE), tz, None
+
+ utc_vals = tzconversion.tz_convert_from_utc(data.view("i8"), tz)
+ data = utc_vals.view(DT64NS_DTYPE)
  elif inferred_tz:
  tz = inferred_tz
  elif allow_object and data.dtype == object:

pandas/tests/frame/test_constructors.py

@@ -68,6 +68,19 @@
 
 
 class TestDataFrameConstructors:
+ def test_constructor_dict_with_tzaware_scalar(self):
+ # GH#42505
+ dt = Timestamp("2019-11-03 01:00:00-0700").tz_convert("America/Los_Angeles")
+
+ df = DataFrame({"dt": dt}, index=[0])
+ expected = DataFrame({"dt": [dt]})
+ tm.assert_frame_equal(df, expected)
+
+ # Non-homogeneous
+ df = DataFrame({"dt": dt, "value": [1]})
+ expected = DataFrame({"dt": [dt], "value": [1]})
+ tm.assert_frame_equal(df, expected)
+
  def test_construct_ndarray_with_nas_and_int_dtype(self):
  # GH#26919 match Series by not casting np.nan to meaningless int
  arr = np.array([[1, np.nan], [2, 3]])