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GH-50530: [Python] Assert assume_timezone results at input precision #50368

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GH-50530: [Python] Assert assume_timezone results at input precision #50368

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GH-50530: [Python] Assert assume_timezone results at input precision
anxkhn Jul 27, 2026
a104cd4
GH-50530: [Python] Pin DST fixture to nanoseconds
anxkhn Jul 27, 2026
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26 changes: 15 additions & 11 deletions python/pyarrow/tests/test_compute.py
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Original file line number Diff line number Diff line change
Expand Up @@ -2757,7 +2757,7 @@ def test_assume_timezone():
"2008-12-29T00:00:00.0",
"2012-01-01T01:02:03.0"])
nonexistent = pd.to_datetime(["2015-03-29 02:30:00",
"2015-03-29 03:30:00"])
"2015-03-29 03:30:00"]).as_unit("ns")

@raulcd raulcd Aug 13, 2026

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why is this now required?

@rok rok Aug 13, 2026 •
edited
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I think my comment still stands #50368 (comment), though you'll need to trim some timestamps so precision will match the unit.

@rok rok Aug 13, 2026

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E.g.: 1970-01-01T00:00:59.123456789 -> 1970-01-01T00:00:59.123 when you do "ms".

ambiguous = pd.to_datetime(["2018-10-28 01:20:00",
"2018-10-28 02:36:00",
"2018-10-28 03:46:00"])
Expand Down Expand Up @@ -2797,17 +2797,18 @@ def test_assume_timezone():
pc.assume_timezone(nonexistent_array,
options=options_nonexistent_raise)

expected = pa.array(nonexistent.tz_localize(
timezone, nonexistent="shift_forward"))
result = pc.assume_timezone(
nonexistent_array, options=options_nonexistent_latest)
expected.equals(result)

expected_type = pa.timestamp(nonexistent_array.type.unit, tz=timezone)
expected = pa.array(nonexistent.tz_localize(
timezone, nonexistent="shift_backward"))
timezone, nonexistent="shift_forward"), type=expected_type)
assert expected.equals(result)

result = pc.assume_timezone(
nonexistent_array, options=options_nonexistent_earliest)
expected.equals(result)
expected = pa.array(nonexistent.tz_localize(
timezone, nonexistent="shift_backward"), type=expected_type)
assert expected.equals(result)

options_ambiguous_raise = pc.AssumeTimezoneOptions(timezone)
options_ambiguous_latest = pc.AssumeTimezoneOptions(
Expand All @@ -2820,15 +2821,18 @@ def test_assume_timezone():
f"timezone '{timezone}'"):
pc.assume_timezone(ambiguous_array, options=options_ambiguous_raise)

expected = ambiguous.tz_localize(timezone, ambiguous=[True, True, True])
result = pc.assume_timezone(
ambiguous_array, options=options_ambiguous_earliest)
result.equals(pa.array(expected))
expected_type = pa.timestamp(ambiguous_array.type.unit, tz=timezone)
expected = pa.array(ambiguous.tz_localize(
timezone, ambiguous=[True, True, True]), type=expected_type)
assert result.equals(expected)

expected = ambiguous.tz_localize(timezone, ambiguous=[False, False, False])
result = pc.assume_timezone(
ambiguous_array, options=options_ambiguous_latest)
result.equals(pa.array(expected))
expected = pa.array(ambiguous.tz_localize(
timezone, ambiguous=[False, False, False]), type=expected_type)
assert result.equals(expected)


def _check_temporal_rounding(ts, values, unit):
Expand Down
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