"""
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Note: includes tests for `last`
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"""
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import pytest
|
|
import pandas as pd
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from pandas import (
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DataFrame,
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bdate_range,
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)
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import pandas._testing as tm
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|
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class TestFirst:
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def test_first_subset(self, frame_or_series):
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ts = tm.makeTimeDataFrame(freq="12h")
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ts = tm.get_obj(ts, frame_or_series)
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result = ts.first("10d")
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assert len(result) == 20
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ts = tm.makeTimeDataFrame(freq="D")
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ts = tm.get_obj(ts, frame_or_series)
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result = ts.first("10d")
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assert len(result) == 10
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result = ts.first("3M")
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expected = ts[:"3/31/2000"]
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tm.assert_equal(result, expected)
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result = ts.first("21D")
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expected = ts[:21]
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tm.assert_equal(result, expected)
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result = ts[:0].first("3M")
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tm.assert_equal(result, ts[:0])
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def test_first_last_raises(self, frame_or_series):
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# GH#20725
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obj = DataFrame([[1, 2, 3], [4, 5, 6]])
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obj = tm.get_obj(obj, frame_or_series)
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msg = "'first' only supports a DatetimeIndex index"
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with pytest.raises(TypeError, match=msg): # index is not a DatetimeIndex
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obj.first("1D")
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msg = "'last' only supports a DatetimeIndex index"
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with pytest.raises(TypeError, match=msg): # index is not a DatetimeIndex
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obj.last("1D")
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def test_last_subset(self, frame_or_series):
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ts = tm.makeTimeDataFrame(freq="12h")
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ts = tm.get_obj(ts, frame_or_series)
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result = ts.last("10d")
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assert len(result) == 20
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ts = tm.makeTimeDataFrame(nper=30, freq="D")
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ts = tm.get_obj(ts, frame_or_series)
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result = ts.last("10d")
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assert len(result) == 10
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result = ts.last("21D")
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expected = ts["2000-01-10":]
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tm.assert_equal(result, expected)
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result = ts.last("21D")
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expected = ts[-21:]
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tm.assert_equal(result, expected)
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result = ts[:0].last("3M")
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tm.assert_equal(result, ts[:0])
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@pytest.mark.parametrize("start, periods", [("2010-03-31", 1), ("2010-03-30", 2)])
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def test_first_with_first_day_last_of_month(self, frame_or_series, start, periods):
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# GH#29623
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x = frame_or_series([1] * 100, index=bdate_range(start, periods=100))
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result = x.first("1M")
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expected = frame_or_series(
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[1] * periods, index=bdate_range(start, periods=periods)
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)
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tm.assert_equal(result, expected)
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def test_first_with_first_day_end_of_frq_n_greater_one(self, frame_or_series):
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# GH#29623
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x = frame_or_series([1] * 100, index=bdate_range("2010-03-31", periods=100))
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result = x.first("2M")
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expected = frame_or_series(
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[1] * 23, index=bdate_range("2010-03-31", "2010-04-30")
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)
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tm.assert_equal(result, expected)
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@pytest.mark.parametrize("func", ["first", "last"])
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def test_empty_not_input(self, func):
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# GH#51032
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df = DataFrame(index=pd.DatetimeIndex([]))
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result = getattr(df, func)(offset=1)
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tm.assert_frame_equal(df, result)
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assert df is not result
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