57 lines
1.8 KiB
Python
57 lines
1.8 KiB
Python
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# Arithmetic tests specific to DatetimeIndex are generally about `freq`
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# rentention or inference. Other arithmetic tests belong in
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# tests/arithmetic/test_datetime64.py
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import pytest
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from pandas import (
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Timedelta,
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TimedeltaIndex,
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Timestamp,
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date_range,
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timedelta_range,
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)
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import pandas._testing as tm
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class TestDatetimeIndexArithmetic:
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def test_add_timedelta_preserves_freq(self):
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# GH#37295 should hold for any DTI with freq=None or Tick freq
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tz = "Canada/Eastern"
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dti = date_range(
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start=Timestamp("2019-03-26 00:00:00-0400", tz=tz),
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end=Timestamp("2020-10-17 00:00:00-0400", tz=tz),
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freq="D",
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)
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result = dti + Timedelta(days=1)
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assert result.freq == dti.freq
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def test_sub_datetime_preserves_freq(self, tz_naive_fixture):
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# GH#48818
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dti = date_range("2016-01-01", periods=12, tz=tz_naive_fixture)
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res = dti - dti[0]
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expected = timedelta_range("0 Days", "11 Days")
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tm.assert_index_equal(res, expected)
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assert res.freq == expected.freq
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@pytest.mark.xfail(
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reason="The inherited freq is incorrect bc dti.freq is incorrect "
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"https://github.com/pandas-dev/pandas/pull/48818/files#r982793461"
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)
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def test_sub_datetime_preserves_freq_across_dst(self):
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# GH#48818
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ts = Timestamp("2016-03-11", tz="US/Pacific")
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dti = date_range(ts, periods=4)
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res = dti - dti[0]
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expected = TimedeltaIndex(
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[
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Timedelta(days=0),
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Timedelta(days=1),
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Timedelta(days=2),
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Timedelta(days=2, hours=23),
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]
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)
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tm.assert_index_equal(res, expected)
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assert res.freq == expected.freq
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